@article {49927, title = {Transfer and incorporation of heritable symbiotic fungi into non-host plants}, number = {60706648}, year = {2011}, month = {March 8, 2011}, address = {United States}, abstract = { A first plant species or a part thereof may be produced which has stably and heritably integrated therein one or more endophytic fungi which are derived from a second, different plant species. This first plant species is not a host plant for the endophytic fungi in nature. These resultant first plant species containing the endophytic fungi exhibit substantially increased vigor, altered morphology and chemistry, and increased reproductive potential compared to non-treated controls.}, url = {http://patents.com/us-7901927.html}, author = {J.R. Barrow and M.E. Lucero} } @article {50162, title = {Do symbiotic microbes have a role in plant evolution, performance and response to stress?}, journal = {Communicative and Integrative Biology}, volume = {1}, number = {1}, year = {2008}, month = {September 1, 200}, pages = {69-73}, abstract = {

Vascular plants have been considered as autonomous organisms especially when their performance has been interpreted at the genome and cellular level. In reality, vascular plants provide a unique ecological niche for diverse communities of cryptic symbiotic microbes which often contribute multiple benefits, such as enhanced photosynthetic efficiency, nutrient and water use and tolerance to abiotic and biotic stress. These benefits are similar to improvements sought by plant scientists working to develop ecologically sustainable crops for food, fiber and biofuels. Native desert plants include a community of indigenous endosymbiotic fungi that are structural components with cells, tissues, cell cultures, and regenerated plants. These fungi regulate plant growth and development and contribute genes and natural products that enable plants to adapt to changing environments. A method developed for transferring these endophytes from cell cultures to non-host plants promises to be a revolutionary approach for the development of novel plant germplasm and has application in the field of plant biotechnology.

}, keywords = {cryptic, Symbiotic, vascular}, url = {/files/bibliography/08-033.pdf}, author = {J.R. Barrow and M.E. Lucero and I. Reyes-Vera and Kris Havstad} } @article {50309, title = {Endosymbiotic fungi structually integrated with leaves reveals a lichenous condition of C4 grasses}, journal = {In Vitro Cellular and Development Biology - Plants}, volume = {43}, year = {2007}, month = {March 11, 2007}, pages = {65-70}, abstract = {This paper addresses the assumed autonomy of vascular plants by revealing the presence of an obligate fungus structurally integrated with leaf anatomy of C4 grasses. We examined leaf surfaces of 26 species representing 14 genera of C4 grasses. In all species, we found similarities between leaf surface microhair-like structures and Uredomycete teliospores. These bicellular structures produced hyphae and spores, confirming they were fungal, rather than plant tissue. The plant-fungus structural morphology was also observed in Bouteloua eriopoda plants regenerated from embryonic meristem cells. The conserved symbiosis between fungi and C4 grasses suggests a lichenous association with evolutionary significance. The structural integration of endosymbiotic fungi with cells and tissues offers novel and unexplored approaches to developing physiological, ecological and systematic models of C4 grasses.}, keywords = {C4 grasses, endosymbiotic, fungi, lichenous}, url = {/files/bibliography/07-013.pdf}, author = {J.R. Barrow and M.E. Lucero and I. Reyes-Vera and Kris Havstad} } @proceedings {50310, title = {Fungal genomes that influence basic physiological processes that enhance survival of black grama and fourwing saltbush in arid southwestern rangelands}, number = {RMRS-P-47}, year = {2007}, month = {August 10-12, 20}, pages = {123-131}, address = {Lubbock, TX}, abstract = {Symbiotic fungi confer multiple benefits such as enhanced photosynthetic rates and drought tolerance in host plants. Shrubs and grasses of southwestern deserts are colonized by symbiotic fungi that cannot be removed by conventional sterilization methods. These fungi were extensively studied in Bouteloua eriopoda (Torr.) Torr. and Atriplex canescens (Pursh) Nutt. over a wide range of locations and environmental conditions. Fungi were intrinsically integrated with cells, tissues, and regenerated plant cultures. These composite plant-fungus organisms are comprised of more than one fungal species. Fungal association with photosynthetic cells, accumulation of lipids provided evidence for carbon management. Fungal biofilms that coat cells, tissues, roots, and leaves suggest that they protect cells, roots, and leaves from direct exposure to stressed environments. Associations with vascular tissues suggested a role in resource transport. Association with stomata indicates an influence in gas exchange, photosynthesis, and evapotranspiration. Transfer of fungal endophytes from native plants to nonhost plants resulted in substantial modifications in root, shoot morphology and biomass, chlorophyll content, and fruiting. Host plants are modified by fungi at the genetic, cellular, and physiological levels and positively enhance ecological fitness.}, keywords = {associations, composite, fungi, manipulation, native plants}, url = {http://www.fs.fed.us/rm/pubs/rmrs_p047/rmrs_p047_123_131.pdf}, author = {J.R. Barrow and M.E. Lucero and P. Osuna and Reyes, I. and Aaltonen, R.E.} } @proceedings {50410, title = {Symbiotic fungi that influence vigor, biomass and reproductive potential of native bunch grasses for remediation of degraded semiarid rangelands}, year = {2006}, month = {June 6-8, 2006}, address = {Cedar City, UT}, abstract = {A steady decline of perennial bunch grasses in arid rangelands has resulted in losses of productivity and germplasm. Remediation is costly and rarely successful. Cryptic symbiotic fungi, structurally integrated with cells and organs of native plants cannot be separated from host plant tissue. However, they were successfully transferred from cell cultures of native plants to other native grasses and tomato. Fungi in recipient plants were heritable and substantially enhanced vigor, biomass and reproductive potential. The transfer of novel fungal symbionts to other native or crop plants may offer an alternative method of improving plant performance without modifying native plant germplasm.}, keywords = {fungi, Symbiotic}, author = {J.R. Barrow and M.E. Lucero and I. Reyes-Vera} } @proceedings {50532, title = {Hybrid vigor, structural modification, and enhanced plant performance induced by symbiotic fungi-plant interactions}, year = {2005}, month = {July 30-August 5}, address = {Hilo, Hawaii}, abstract = {Communities of symbiotic fungi are intrinsically integrated with single cells, tissues, and organs of desert plants. They are obligately associated with living tissues and generally cannot be isolated and cultured separately. Symbiotic fungi indigenous to native desert plants were transferred, using cell culture methods, to nonhost plants and reciprocally transferred between native grasses. Crop and native plants with recipient fungi have astounding and increased levels of vigor. Up to fivefold increases in root and shoot biomass and substantial morphological changes and reproductive potential were obtained. Enhanced chlorophyl and phosphorous content were common responses. Once integrated, fungi were intimately interfaced with the plasmalema of the new host plant and were ecto-cytoplasmically inherited. This technology accesses a previously unexplored source of genetic variability within native ecosystems with the potential of immediate transfer to improve tolerance of native and crop plants to stress, disease, and pests. Symbiotic fungal transfers provides a powerful alternative for genetic improvement of plants.}, keywords = {enhanced plant performance, hybrid vigor, structural modification, symbiotic fung-plant interactions}, author = {J.R. Barrow and M.E. Lucero and P. Osuna-Avila and I. Reyes-Vera and Aaltonen, R.E.} } @conference {50626, title = {Endophytic fungi associated with shrubs and grasses of the northern Chihuahuan Desert and a potential role in drought tolerance}, booktitle = {Annual Meeting, Canadian Botanical Association}, year = {2004}, month = {June 26-30, 2004}, pages = {p. 10}, address = {Winnipeg, Manitoba, Canada }, abstract = {Native grasses and shrubs of the northern Chihuahuan Desert are predominantly colonized by dark septate endophytes. Methods using stains that target fungal chitin and internal lipids with high-magnification, light microscopy and scanning electron microscopy revealed a much greater incidence of colonization than was previously thought. In-vitro-regenerated plants from meristematic stem cells were also found to be colonized with the same fungi observed in plants from native populations. Originally thought to be restricted to roots, they are conspicuously present in meristems, sieve elements, xylem vessels of roots and leaves and in photsynthetic cells and stomata. Differing from pathogens and mycorrhizal fungi that have localized patterns of colonization, they systemically inhabit the entire apoplastic network of below- and aboveground organs. They encapsulate host cell protoplasts and are vertically transmitted by seed. Hyphal networks and biofilms that encapsulate all cells and tissues of micropropagated and native plants prevent their direct exposure to harsh external environments. The intimate nature of the association with all plant cells and organs indicates that these native desert shrubs and grasses function as composite plant-fungus organisms. A potential role in managing basic physiological processes that positively enhance plant survival in arid ecosystems is suggested.}, keywords = {Chihuahuan Desert, colonization, endophytes, fungi}, author = {J.R. Barrow and Aaltonen, R.E. and P. Osuna-Avila and I. Reyes-Vera} } @article {50629, title = {Fungal endophytes intrinsically associated with micropropagated plants regenerated from native Bouteloua eriopoda Torr. and Atriplex canescens (Pursh) Nutt.}, journal = {In Vitro Cellular and Developmental Biology-Plant}, volume = {40}, number = {6}, year = {2004}, month = {November 1, 2004}, pages = {608-612}, abstract = {Black grama (Bouteloua eriopoda) and fourwing saltbush (Atriplex canescens) are important grass and shrub species in arid rangelands of the northern Chihuahuan Desert. They are naturally colonized by dark septate endophytic fungi that cannot be eliminated by seed disinfestation. Plants were regenerated from both species and appeared to be fungus free in axenic cultures. Analysis of callus and regenerated plants of both species using dual staining with light and scanning electron microscopy revealed fungal endophytes intrinsically associated with cells, roots and leaves of regenerated plants that are also associated with native plants. Fungal layers and biofilms prevent direct exposure of callus, root or leaf tissues to the external environment. Micropropagation is a valuable tool for identifying key fungal endophytes that enhance drought tolerance in native desert plants.}, keywords = {arid, biofilms, drought, mycorrhizae, symbiosis}, url = {/files/bibliography/04-008.pdf}, author = {J.R. Barrow and P. Osuna-Avila and I. Reyes-Vera} } @conference {50627, title = {Fungal genomes that influence basic physiological processes that enhance survival of black grama and forwing saltbush in arid Southwestern rangelands}, booktitle = {13th Wildland Shrub Symposium, Shrubland Dynamics: Fire and Water}, year = {2004}, month = {August 10-12, 20}, address = {Lubbock, TX}, abstract = {Symbiotic fungi are generally known to enhance photosynthetic rates and drought tolerance in host plants, but mechanisms are currently unresolved. Shrubs and grasses of southwestern deserts are colonized by symbiotic fungi that cannot be removed by conventional sterilization methods. These fungi were extensively studied in native plants over a wide range of locations and environmental conditions. Fungi associated with native plants were also found to be intrinsically integrated with cells, tissues and regenerated plant cultures. Native grasses and shrubs were found to be composite plant-fungus organisms comprised of at least two fungal species. It is suggested that these inherent associations modify their hosts at the genetic, cell and physiological levels and positively enhance ecological fitness. Colonization of photosynthetic cells, encapsulation of chloroplasts and accumulation of lipids provided evidence for host modification and performance. Carbon management is suggested by the substantial quantities of high energy lipids that are stored and transported in sieve elements. Lipids converted to biofilms protected cells, tissues, roots and leaves from direct exposure to the external environment. Unique associations with xylem vessels suggested that fungi may actively transport water during drought. Colonization of the stomatal complex indicated a role in regulating gas exchange, photosynthesis and water loss by transpiration. We suggest that symbiotic fungi have a multifunctional role of enhancing drought tolerance of native desert plants. Improvement of native plants by conventional breeding or gene transfers is expensive and time-consuming. Manipulation of fungi rather than plants may provide a more efficient alternative for their improvement.}, keywords = {associations, composite, fungi, manipulation, native plants}, author = {J.R. Barrow and P. Osuna-Avila and I. Reyes-Vera} } @conference {50630, title = {Fungal genomes that influence basic physiological processes that enhance survival of black grama and fourwing saltbush in arid Southwestern rangelands}, booktitle = {13th Wildland Shrub Symposium, Shrubland Dynamics: Fire and Water}, year = {2004}, month = {August 10-12, 20}, address = {Lubbock, TX}, abstract = {Symbiotic fungi are generally known to enhance photosynthetic rates and drought tolerance in host plants, but mechanisms are currently unresolved. Shrubs and grasses of southwestern deserts are colonized by symbiotic fungi that cannot be removed by conventional sterilization methods. These fungi were extensively studied in native plants over a wide range of locations and environmental conditions. Fungi associated with native plants were also found to be intrinsically integrated with cells, tissues and regenerated plant cultures. Native grasses and shrubs were found to be composite plant-fungus organisms comprised of at least two fungal species. It is suggested that these inherent associations modify their hosts at the genetic, cell and physiological levels and positively enhance ecological fitness. Colonization of photosynthetic cells, encapsulation of chloroplasts and accumulation of lipids provided evidence for host modification and performance. Carbon management is suggested by the substantial quantities of high energy lipids that are stored and transported in sieve elements. Lipids converted to biofilms protected cells, tissues, roots and leaves from direct exposure to the external environment. Unique associations with xylem vessels suggested that fungi may actively transport water during drought. Colonization of the stomatal complex indicated a role in regulating gas exchange, photosynthesis and water loss by transpiration. We suggest that symbiotic fungi have a multifunctional role of enhancing drought tolerance of native desert plants. Improvement of native plants by conventional breeding or gene transfers is expensive and time-consuming. Manipulation of fungi rather than plants may provide a more efficient alternative for their improvement.}, keywords = {associations, composite, fungi, manipulation, native plants}, author = {J.R. Barrow and P. Osuna-Avila and I. Reyes-Vera} } @inbook {50628, title = {A Staining Method for Systemic Endophytic Fungi in Plants}, booktitle = {Emerging Concepts in Plant Health Management}, volume = {Chapter 5}, year = {2004}, note = {Publisher is saving book chapters on CD-ROM; each author will receive a copy. December 2, 2003.}, month = {2004}, pages = {61-67}, publisher = {Research Signpost}, organization = {Research Signpost}, address = {Kerala, India}, abstract = {Native desert plants are extensively colonized by dark septate fungal endophytes (DSE). These are characterized by stained or pigmented hyphae and microsclerotia growing inter- and intra-cellularly within the root cortex. A dual-staining method was developed using trypan blue that targets fungal chitin and sudan IV that targets internal fungal lipid bodies. Roots and leaves of dominant grasses and shrubs of arid southwestern rangeland were dual-stained to determine the nature and extent of colonization by DSE fungi. Fungal structures ranged from lipid bearing protoplasts, hyaline, stained and melanized hyphae and microsclerotia. They inhabit the apoplastic spaces of roots and shoots. Predominant fungal structures are protoplasts in physiologically active tissues that are identified with stained, associated lipid bodies. This method shows colonization by DSE fungi is more extensive than was previouisly throught.}, url = {/files/bibliography/04-079.pdf}, author = {J.R. Barrow and Aaltonen, R.E.} } @article {50741, title = {Atypical morphology of dark septate fungal root endophytes of Bouteloua in arid southwestern USA rangelands}, journal = {Mycorrhiza}, volume = {135}, year = {2003}, month = {October 1, 2003}, pages = {239-247}, abstract = {Roots of native grama grasses (Bouteloua sp) analyzed for internal colonization of fungal endophytes using histochemical stains and differential interference microscopy. Unique and atypical fungal structures were found to form a continuous nonpathogenic colonization of sieve elements, cortical, epidermal cells, and the root hairs and surface. Unique interfaces with sieve elements, the accumulation of large quantitie of lipids and their distribution throughout the root and the deposition of mucilage on the root surface indicates that dark septate fungi manage carbon between the plant and soil and protect the plant from drought stress. The nondestructive colonization of sieve elements suggests a novel plant-fungal association not previously reported.}, keywords = {Bouteloua, fungal endophytes, grama grasses, structures}, url = {/files/bibliography/03-045.pdf}, author = {J.R. Barrow} } @conference {50742, title = {A perceived role of carbon and water management by systemic dark septate fungi in Bouteloua eriopida (Torr.) Torr. in an arid ecosystem}, booktitle = {Fourth International Conference on Mycorrhizae}, year = {2003}, month = {August 10-15, 20}, address = {Montreal, Canada}, abstract = {Dark septate endophytic (DSE) fungi are the prevalent symbionts of native grasses and shrubs in arid southwestern USA rangelands. The nature and extent of colonization of Bouteloua eriopida (Torr.) Torr., an important native range grass of the northern Chihuahuan Desert, was evaluated using dual staining, light and electron microscopy. Several unique and ecologically important features of DSE fungi were revealed. Fungi preferentially reside in the apoplastic environment and function as protoplasts identified by associated lipid bodies. They form systemic intercellular networks in plants and intracellular structures within sieve elements, parenchyma and cortical cells. Endophyte-free plants have not been developed but some fungi were cultured independently. The composite association results in a hybrid organism better equipped to survive in severe nutrient and water stressed ecosystems. Fungi formed stained and pigmented hyphae and microsclerotia, characteristic of DSE in less active tissues. Loosely organized hyphae, embedded within a mucilaginous matrix on the root surface, suggested a protective barrier from dry soil. A precisely organized hyphal network on the leaf surface suggested a protective barrier from atmospheric stress. Colonization of guard and subsidiary cells of the stomatal complex suggested an influence of stomatal regulation and transpiration. The size and quantity of fungal associated lipid bodies suggested a role of carbon storage and management within the ecosystem.}, author = {J.R. Barrow and Aaltonen, R.E.} } @conference {50740, title = {Unique characteristics of a systemic fungal endophyte of native grasses and shrubs in arid southwestern rangelands}, booktitle = {Wildland Shrub Symposium}, year = {2003}, month = {January 8, 2003}, pages = {6}, abstract = {Native grasses and shrubs in arid southwestern rangelands are more extensively colonized by dark septate endophytic fungi than by traditional mycorrhizal fungi. A histochemical method was developed that revealed active internal structures that have not been observed using conventional protocol for fungal analysis. These fungi nonpathogenically and totally colonize all sieve elements, cortical and epidermal cells. They grow inter and intracellulary forming an intimate integrated association with all root cells. Their internal morphology is often atypical of commonly recognized symbiotic or pathogenic fungal colonization. These endophytes accumulate and disperse large quantities of lipids through the root. They form a mucilage layer on the root surface which protects the root and maintains hydraulic continuity with dry soil. Our results suggest that these fungi function as carbon managers and enhance nutrient and water uptake in arid ecosystems.}, author = {J.R. Barrow} } @article {50838, title = {Phosphorus solubilization and uptake by dark septate fungi in fourwing saltbush, Atriplex canescens (Pursh) Nutt.}, journal = {Journal of Arid Environments}, volume = {51}, year = {2002}, month = {July 1, 2002}, pages = {449-459}, abstract = {Fourwing saltbush, Atriplex canescens (Pursh) Nutt., is an ecologically important range plant in arid southwestern USA rangelands. Native populations of this non-mycorrhizal, chenopodiacious shrub are extensively colonized by melanized dark septate fungi (DS). Seedling radicles of A. canescens are colonized at germination by a DS fungus identified as Aspergillus ustus that cannot be removed by heat or sterilization. The mutualistic association of A. canescens and A. ustus was evaluated by comparing plants treated with either no P (0P) or adequate plant available soluble P (30 ppm) in the root zone (AAP). Plant unavailable P (as rock phosphate (RP) or tricalcium phosphate (TCP)) was separated from the roots by a barrier that only allowed the passage of fungi. Plant roots in all treatments were internally colonized by A. ustus. A significant mutualistic response was observed in the RP and TCP treatments. Evidence for enhanced P uptake by the plant via the fungus was greater shoot and root biomass production and fungal density. Plants receiving P from plant unavailable P from TCP below the barrier via the fungus had equivalent shoot biomass and greater root biomass (P< 0.01) than plants receiving soluble P (AAP). Phosphorus use efficiency was increased in plants supplied P by fungi from plant unavailable P treatments. It was concluded that A. ustus utilized plant carbon for growth and the solubilization, uptake and transport of P to enhance shoot and root biomass. The potential benefits of DS fungi in arid ecosystems is discussed.}, keywords = {Atriplex canescens, fourwing saltbush, phosphorus solubilization, plant carbon, potential benefits}, url = {/files/bibliography/02-001.pdf}, author = {J.R. Barrow and Avila-Osuna, P.} } @proceedings {50966, title = {Carbon transport by symbiotic fungi in fourwing saltbush, Atriplex canescens (Pursh) Nutt.}, volume = {RMRS P-21}, year = {2001}, month = {June 13-15, 2000}, pages = {291-294}, publisher = {USDA Forest Service Proceedings RMRS-P-00.2001}, address = {Provo, UT}, abstract = {Mycorrhizal fungi enhance the nutrition and survival of host plants in native ecosystems. Arid rangelands severely challenge plants because of chronic nutrient and water stress. Fourwing saltbush, Atriplex canescens (Pursh) Nutt., a dominant and important shrub of western arid rangelands, generally considered to be non-mycorrhizal, is more extensively colonized by dark septate (DS) fungal endophytes than by traditional mycorrhizal fungi. Roots of fourwing saltbush colonized by DS fungi were stained with sudan IV and analyzed with differential interference microscopy which revealed extensive internal colonization by vacuolated hyaline hyphae that is not evident using conventional fungus staining methods. Fungal vacuoles accumulated substantial quantities of lipids in the sieve elements and cortex when roots were physiologically active. The widespread colonization of fourwing saltbush by DS fungi and their extensive accumulation of lipids ssuggests that these fungi transport and manage carbon in arid ecosystems. Their potential role in ecosystems stability is discussed.}, keywords = {Atriplex canescens, carbon, fourwing saltbush, Mycorrhizal fungi, plant survival}, url = {/files/bibliography/01-006.pdf}, author = {J.R. Barrow} } @article {50965, title = {Evaluation of the internal colonization of Atriplex canescens (Pursh) Nutt. roots by dark septate fungi and the influence of host physiological activity}, journal = {Mycorrhiza}, volume = {11}, number = {4}, year = {2001}, month = {May 12, 2001}, pages = {199-205}, chapter = {199}, abstract = {

Dark septate (DS) fungal endophytes are the primary root colonizers of fourwing saltbush, Atriplex canescens (Pursh) Nutt, a dominant and ecologically important shrub in southwestern USA rangelands. These fungi are characteristically identified as stained or pigmented hyphae and microsclerotia in the root cortex using conventional fungus staining methods. A. canescens roots colonized by DS fungi were stained with sudan IV and analyzed with differential interference microscopy (DIC). This method revealed substantial internal colonization of the cortex and vascular cylinder by vacuolated hyaline hyphae that were not evident when stained with trypan blue. Hyaline hyphae were internal extensions of melanized DS hyphae and microsclerotia. Sudan IV intensely stained lipids in fungal vacuoles, further enhancing visibility of internal hyaline hyphae. Melanized hyphae and microsclerotia were more abundant in roots sampled from dormant and relatively inactive plants while hyaline hyphae and lipid accumulation were most prevalent in roots of physiologically active plants. The polymorphic nature of DS fungal endophytes, their dynamic response to metabolic activity, and their similarities and differences relative to aseptate fungal colonization in A. canescens roots are discussed.

}, keywords = {Atriplex canescens, dark septate, evaluation, fourwing saltbush, fungal endophytes, internal colonization}, doi = {10.1007/s005720100111}, url = {/files/bibliography/01-008.pdf}, author = {J.R. Barrow and Aaltonen, R.E.} } @conference {50967, title = {A method for analyzing active internal colonization of dark septate fungal endophytes in grasses and shrubs native to arid southwestern USA rangelands}, booktitle = {Third International Conference on Mycorrhizae}, year = {2001}, month = {July 8-13, 2001}, pages = {Abstract No. P1-68}, address = {Adelaide, Australia}, abstract = {Dominant native grasses and shrubs in arid southwestern USA rangelands are more extensively colonized by dark septate fungal endophytes (DSE) than by conventional mycorrhizal fungi. These endophytes are widespread colonizers in most ecosystems, but their ecological function is currently unresolved. They are readily observed as stained or melanized septate hyphae and microsclerotia on the root surface and in the cortex using fungus specific stains that bind to chitin, a common wall component. Roots of grasses and shrubs native to the northern Chihuahuan Desert were stained with sudan IV, specific for lipids, and analyzed with high magnification differential interference microscopy. Inconspicuous internal hyphal extensions of stained or pigmented hyphae were observed that were not visible using fungus specific stains. These structures were observed in a much greater frequency than the commonly recognized stained or pigmented structures in physiologically active roots. Differential responses to staining were attributed to structural differences and levels of chitin incorporation in the fungal wall. Internal hyphae varied in diameter, wall thickness, and visibility and in many cases were detectable only because of the positive staining of lipids in fungal vacuoles. Internal hyphae grew both inter and intracellularly within the cortex and sieve elements of the vascular cylinder and at time contained substantial quantities of lipids. This method promises to be effective for studying the extent, nature, and possible function of DSE fungi in native ecosystems.}, keywords = {analyzing, arid rangelands, dark septate, fungal endophytes, grasses, internal colonization, shrubs}, author = {J.R. Barrow and Aaltonen, R.E.} } @conference {50968, title = {Unique active internal morphology of dark septate fungal endophytes associated with roots of native grasses and shrubs in an arid ecosystem}, booktitle = {Third International Conference on Mycorrhizae}, year = {2001}, month = {July 8-13, 2001}, pages = {Abstract No. P1-69}, address = {Adelaide, Australia}, abstract = {Plants in arid ecosystems are exposed to severe nutrient and drought stress. Mycorrhizal fungi alleviate these stresses in natural ecosystems. Native grasses and shrubs in arid southwestern USA rangelands are more extensively colonized by dark septate fungal endophytes (DSE) than by conventional mycorrhizal fungi. The function of these endophytes is presently unresolved. Roots of grasses and shrubs native to the northern Chihuahuan Desert were stained with sudan IV, specific for lipids, and analyzed with high magnification differential interference microscopy. Unique, atypical extensions of DS fungi were observed that are not visible using fungus specific stains. Their prevalence in physiologically active roots suggested an active phase of DSE. Hyaline hyphae grew both inter- and intracellularly within the cortical cells and sieve elements and varied in visibility. Some hyphae had distinct hyaline walls, while others sin the sieve elements walls were evident only by positive staining of lipids in their vacuoles. These vacuoles were arranged in a typical linear and branched hyphae manner or they were highly irregular in shape. Large 5-8 um, lipid filled, hyphal vacuoles extended from the vascular cylinder through the cortex to the root surface which was coated with mucilage. The substantial lipid accumulation in hyphae extending from sieve elements to the root surface suggested that DSE fungi enhance rhizodeposition of carbon, the formation of a protective mucilage sheath that maintains hydraulic continuity and root function in dry soil.}, keywords = {dark septate, endophytes, fungal, internal morphology}, author = {J.R. Barrow and Aaltonen, R.E.} } @proceedings {51129, title = {The role of endophytic fungi in the survival and establishment of fourwing saltbush (Atriplex canescens [Pursh] Nutt.) in an arid environment}, year = {1999}, month = {1999}, pages = {1-4}, publisher = {USDA Forest Service, Rocky Mountain Research Station, Proceedings RMRS-P-11}, address = {Ogden, UT}, abstract = {

A seedborne septate fungus (Aspergillus sp.) formed intimate nondestructive interfaces with seedling radicles of germinating fourwing saltbush (Atriplex canescens [Pursh] Nutt.) seedlings. When seedlings were separated from insoluble phosphorus sources with a screen that excluded roots but allowed passage of extraradicle hyphae, which accessed plant insoluble phosphate and transported it through the barrier to the plant. The fungi enhanced phosphorus uptake, biomass production of the host plants and aggregated sand similar to functions attributed to mycorrhizal fungi. The importance of symbiotic fungi in the remediation and stabilization of arid ecosystems is discussed.

}, url = {/files/bibliography/690.pdf}, author = {J.R. Barrow and Feder, I. and Curtis H. Monger} } @article {51260, title = {Fungal root endophytes in fourwing saltbush, Atriplex canescens, on arid rangelands of southwestern USA}, journal = {Arid Soil Research and Rehabilitation}, volume = {11}, year = {1997}, month = {1997}, pages = {177-185}, abstract = {

This research was conducted to determine the nature and incidence of fungal root endophytes on fourwing saltbush, Atriplex canescens (Pursh) Nutt. Root cortex cells of fourwing saltbush in arid rangelands of the southwestern United States were analyzed and found to be regularly colonized with three types of endophytic fungi: septate, vesicular-arbuscular mycorrhizae (VAM), and Chytridiomycetes. Septate fungi were 2.7 times more prevalent than VAM and formed intimate non-pathogenic associations characterized by inter- and intracellular hyphae, coils, microsclerotia, and occasional labyrinthine or "Hartig net" structures similar to those affiliated with ectendomy-corrhizae. External hyphae formed intimate associations with soil and sand panicles. Typically, VAM were characterized by hyphae, vesicles, and (at times) coils. VAM were 2.2 times more prevalent than chytrids. Chytrids were rather common and were expressed as resting and active sporangia found within root cortex cells. The widespread occurrence of these non-destructive fungal associations with plants implies that they have an important role in plant survival in arid environments.

}, keywords = {arid ecology, chytrids, land restoration, mutualism, mycorrhizae, range-land, saprophytic fungi, symbiosis, VAM}, doi = {10.1080/15324989709381470}, url = {/files/bibliography/468.pdf}, author = {J.R. Barrow and Kris Havstad and McCaslin, B D.} } @article {51262, title = {Natural asexual reproduction in fourwing saltbush Atriplex canescens (Pursh) Nutt.}, journal = {Journal of Arid Environments}, volume = {36}, year = {1997}, month = {1997}, pages = {267-270}, abstract = {

Native populations of fourwing saltbush, Atriplex canescens (Pursh) Nutt., are generally naturally seeded. Two populations were found in New Mexico that are asexually propagated by underground stems. The ratios of female to male plants in asexually produced populations differed from naturally seeded populations. This trait appears to be under genetic control and would be valuable in improving fourwing saltbush for revegetation of rangelands.

}, keywords = {reclamation, remediation, restoration, revegetation, sex expression}, url = {/files/bibliography/414.pdf}, author = {J.R. Barrow} } @article {51261, title = {Seed-borne fungal endophytes on fourwing saltbush, Atriplex canescens }, journal = {Arid Soil Research and Rehabilitation}, volume = {11}, number = {4}, year = {1997}, month = {October 1, 1997}, pages = {307-314}, abstract = {

Fourwing saltbush, Atriplex canescens (Pursh) Nutt., produces copious quantities of small seed, with minimal nutrient reserves, protected in a hard porous capsule (utricle) that aids in dispersal. At germination, saprophytic fungi simultaneously colonize the utricle, testa, and root cortex cells of the emerging radicles. Seedling vigor was determined by measuring hypocotyl and radicle lengths after germination on minimal carbon or cellulose-supplemented medium. Comparisons were made between seedlings from utricle-excised and intact seed. Comparisons were also made between surface-sterilized and nonsterile excised seed. Minimal growth responses were observed in germinating seedlings from excised seeds on minimal carbon medium. Fungi, utricles, and cellulose supplementation positively affected seedling vigor. The results support a hypothesis that septate fungi recycle utricles and access organic carbon for seedling establishment.

}, keywords = {arid ecology, endophytic fungi, fertility, germination, land restoration, mutualism, mycorrhizae, native plants, plant nutrition, saprophytic fungi, symbiosis}, doi = {10.1080/15324989709381484}, url = {/files/bibliography/508.pdf}, author = {J.R. Barrow and Kris Havstad and Hubstenberger, J. and McCaslin, B D.} } @conference {51318, title = {Mycorrhizal similarities of septate fungal root endophytes in native plant species of arid ecosystems}, booktitle = {International Conference on Mycorrhizae}, year = {1996}, month = {1996}, abstract = {

Levels of fungal colonization in the roots of fourwing saitbush Atriplex canescens and other dominant native grass and shrub species from an arid ecosystem have been studied. It was shown that colonization by septate fungal colonization was 2.7 times greater fourwing saltbush than colonization by VAM fungi. Historically studies have focused on the role of VAN fungi and how they affect the plant. The septate fungi hear several asimilarities to other types of mycorrhizae. They formed extensive non-dest ve interfaces, primarily by vegetative hyphae, within the root cortex. They enhance nutrient uptake at low concentrations and restrict uptake at high concentrations. They also protect against high salt concentrations. Some are competent decomposers and appear to enhance seedling vigor and establishment by supplying nutrients from external organic matter. They modify soil by binding sand particles to the root surface. We propose that septate fungal endophytes have a major function in ecosystem, processes.

}, url = {/files/bibliography/470.pdf}, author = {J.R. Barrow and McCaslin, B D. and Curtis H. Monger and Feder, I.} } @proceedings {51319, title = {Role of microbes in resource management in arid ecosystems}, volume = {Gen. Tech. Rep. INT-GTR-338}, year = {1996}, month = {May 23-25, 1995}, pages = {1-2}, publisher = {USDA Forest Service, Intermountain Research Station, Gen. Tech. Rep. INT-GTR-338}, address = {Las Cruces, NM}, abstract = {

Three major classes of endophytic fungi were observed in the roots of native grasses and shrubs: (1) vesicular-arbuscular mycorrhizae (VAM), which are known to be important in water and nutrient uptake; (2) septate fungi that formed non-destructive interfaces within root cortex cells and exhibited mycorrhizal like characteristics; and (3) chytridiomycetes were the third major class of fungi observed and preliminary studies suggest they regulate colonization of VAM, septate fungi, and nutrient uptake.\  A hypothesis is proposed on how these fungi function in accessing and managing nutrients and water for survival in arid ecosystems.

}, url = {/files/bibliography/457.pdf}, author = {J.R. Barrow and McCaslin, B D.}, editor = {J.R. Barrow and McArthur, E. Durant and R. E. Sosebee and R. J. Tausch} } @proceedings {51320, title = {Shrubland ecosystem dynamics in a changing environment}, year = {1996}, month = {1996}, keywords = {changing environment, dynamics, shrubland ecosystem}, isbn = {USDA Forest Service General Technical Report INT-GTR-338}, author = {J.R. Barrow and McArthur, E.D. and R. E. Sosebee and R. J. Tausch} } @proceedings {51382, title = {Natural methods of establishing native plants on arid rangelands}, volume = {Gen. Tech. Rep. INT-GTR-315}, year = {1995}, month = {October 19-21, 1}, pages = {44-45}, publisher = {USDA Forest Service, Intermountain Research Station, Gen. Tech. Rep. INT-GTR-315}, address = {Las Vegas, NV}, abstract = {

Desertification of native rangelands is a global problem. Mechanical and chemical approaches to remediate these lands are not universally suitable or appropriate, and often times induce disturbances that escalate rather than resolve the trend. Therefore, we are proposing to utilize natural systems such as wind, water, or animals to disperse seeds of desirable native plant species. These methods would have minimal disturbance on native landscapes. Concepts of water and animal seed dispersal on arid rangelands are discussed.

}, url = {/files/bibliography/435.pdf}, author = {J.R. Barrow and Kris Havstad}, editor = {Roundy, Bruce A. and McArthur, E. Durant and Haley, Jennifer S. and Mann, David K.} } @conference {51435, title = {A role of endophytic fungi in regulating nutrients and energy in plants within a desert ecosystem}, booktitle = {International Symposium and Workshop on Desertification in Developed Countries: Why Can{\textquoteright}t We Control It?}, year = {1994}, month = {October 25-28, 1}, address = {Tucson, AZ}, abstract = {Roots of common native grasses and shrubs growing in arid regions of the southwestern United States were analyzed for symbiotic fungi. In addition to classical interfaces formed by vesicular-arbuscular mycorrhizae, many other types of fungal interfaces were observed. Fungal isolates from roots of native plants formed associations typical of ectendo mycorrhizae with root organ cultures of alfalfa (Medicago sativa L.), blue grama [Bouteloua gracilis (H.B.K) Lag.], alkali sacaton (Sporobolus airoides Torr.), and sideoats grama [Bouteloua curtipendula (Michx.) Torr.]. Infected alfalfa roots accumulated high concentrations of phosphorus butprevented translocation to leaves and stem, while noninfected roots allowed a five-fold increase of phosphorus in plant tops. This indicates that these fungi not only accumulate and store but regulate phosphorus transfer and possibly other essential nutrients and energy sources within the plant. Fungi associated with germinating seed of foaming saltbush [Atriplex canescens (Pursh) Nutt .] were also shown to degrade cellulose of the utricle and transfer carbon to the germinating seedling, which enhanced germination, vigor, and establishment. A hypothesis was developed to explain how endophytic fungi affect survival of native plants and the nutrition of cultivated crops growing in arid regions. An understanding of how these fungi affect native plant communities would be valuable in the management of desert areas.}, author = {J.R. Barrow} } @conference {51470, title = {The use of natural passive methods of dispersing and establishing native plants on arid rangelands}, booktitle = {Revegetation and Ecology Session, USDI Fish and Wildlife Service}, year = {1993}, month = {1993}, pages = {7-8}, abstract = {Deterioration of arid rangelands around the world is a major concern to the present and future management of these vast land resources. Revegetation efforts are hampered by excessive inputs with low expectations of success. We are implementing natural passive methods such as water, wind, and animals to disperse and establish desirable grass and shrub species on the Jornada Experimental Range in southern New Mexico. In bajada habitats, we have established small seeding blocks and gully seeders along shallow, gentle sloping drainages utilizing portable watering systems. Once desirable grasses and shrubs are established, they will slow water runoff, deposit soil and debris, and produce seed for downstream seeding. In coppice dune habitats, we are establishing fourwing saltbush (Atriplez canescens (Pursh) Nutt.) in seeding blocks for wind and rodent dispersal of seed to determine its competitive ability with mesquite. Additionally, we are determining the potential of using livestock to increase seed of desirable species in specific areas. These low input methods are being incorporated into routine animal and land management practices that are expected to have long-term influences on changing vegetation patterns.}, keywords = {dispersing, establishing, native plants, natural passive methods}, author = {J.R. Barrow} } @article {51515, title = {Recovery and germination of gelatin-encapsulated seeds fed to cattle}, journal = {Journal of Arid Environments}, volume = {22}, year = {1992}, note = {Full Article from Journal of Arid Environments posted on this website with permission from Elsevier. http://www.sciencedirect.com/science/journal/01401963}, month = {1992}, pages = {395-399}, abstract = {

Artificial reseeding of marginal farmlands, wildlands or rangelands by mechanical mens is expensive and often unsuccessful. This study conducted to determinethe recovery and germinability of seeds of the southwestern USA rangeland forages fed to cattle. Seed of fourwing saltbush (Atriplex canescens), alkali sacaton (Sporobolus airoides), blue panicgrass (panicum antidotale), and sideoats grama (Bouteloua curtipendula) were administered in gelatin capsules to seers maintained on a moderate-qulaity alfalfa (medicago sative) diet. Approximately 95\% of the recovered seed passed through the steers wihink 72 h after dosing, but recovery varied among species. Total recovery was 9.5, 46.4, 61.8, and 0\% for fourwing saltbush, alkali sacaton, blue panicgrass adn sideoats grama, respectively. Fourwing saltbush, blue panicgrass, and alkali sacaton retained viability and germinated in the fecal material. Germination of seeds recovered 48 h post ingestion was 14.8, 50.1 and 41.4\% for fourwing saltbush, alkali sacaton and blue panicgrass, use of gelatin capsules would be an effective method for easily feeding known quantities of seeds to livestock in small herds and could be incorporated with other common and necessary livestock handling practices.

}, doi = {10.1016/S0140-1963(18)30582-2}, url = {/files/bibliography/381.pdf}, author = {J.R. Barrow and Kris Havstad} } @proceedings {51514, title = {Use of floodwater to disperse grass and shrub seeds on native arid lands}, year = {1992}, month = {1992}, pages = {167-169}, publisher = {USDA Forest Service, GTR-INT 289}, address = {Sun Valley, ID}, abstract = {Dry stream channels of arid rangelands are typically more fertile and mesic than adjacent slopes. The productivity of these channels is evident by their relatively abundant plant biomass. Substantial down-channel establishment of seeded and native species from root-plowed and seeded strips was observed on the Jornada Experimental Range. There appears to be good potential for using floodwater as a low-input method of seed dispersal for subsequent revegetation of natural waterways.}, url = {/files/bibliography/362.pdf}, author = {J.R. Barrow} } @proceedings {51556, title = {The use of alternative natural methods of reseeding arid native grasslands}, year = {1991}, month = {April 22-26, 199}, pages = {No. 354}, abstract = {Many native arid grasslands of the world have been invaded by noxious desert shrubs which have degraded overall habitat values, especially forage productivity and soil stability. This trend must be altered, but revegetation by mechanical means is expensive and the chance of successful plant establishment is low. Animals and water, which are successfully utilized by native species for distributing seeds and establishing new plants, were used to study their potential in dispersing seeds of some forage species adapted to arid conditions. Blue panicgrass (Panic um antidotale Betz.), alkali sacaton (Sporobolus airoides Torr.), and fourwing saltbush (Atriplex canescens Pursh Nutt.) seed were inserted directly into steer (Bos taurus) rumens by gelatin capsules. About 50\% of the viable seed passed in less than 72 hours. Quail (Colinus virginianus) fed the small seeded grasses passed from 500 to 2000 viable seed per bird within 24 hours. Grasses were transported and established downstream in the more fertile and mesic flood plain areas from artificially seeded plots growing along natural desert arroyos. A seeder was developed that released seeds into these channels during flooding. They were transported downstream and deposited in moist sediment favorable for germination. These methods are inexpensive in terms of cost, labor, and equipment and could be integrated into land and animal management practices that may potentially increase seeding opportunity for desirable forage species.}, keywords = {arid grasslands, natural methods, reseeding}, author = {J.R. Barrow and Kris Havstad and Gibbens, Robert P.} } @conference {51604, title = {Alternative methods of seeding native lands}, booktitle = {Annual Meeting of the American Society of Agronomy}, year = {1990}, month = {October 21-26, 1}, pages = {163}, address = {San Antonio, TX}, abstract = {Mechanical reseeding of native and less productive lands is usually prohibitive. Native plants successfully utilize natural means, such as animals, water, or wind, to distribute their seeds. We are exploring the possibilities of using livestock, wildlife, and natural waterways for seed dispersal. Steers were bolused with gelatin capsules with known quantities of either a shrub, fourwing saltbush, or one of two grasses, blue panic grass or alkali sacaton. These species are adapted to arid range conditions. Up to 60\% of the seeds were recovered in steer feces within 72 hours after bolusing, and near normal germination resulted. Quail fed the grass seeds, passed over 95\% of the viable seed within 24 hours, and averaged 530 blue panic and 1,800 alkali sacaton seeds per bird. Observations were made of seed dispersed from seeded plots and from a flood activated seeder along natural drainage ways. The use of animals or water to disperse seeds of desirable forage species potentially could be an effective and economical means for establishing these species in areas where conventional methods are not practical.}, keywords = {alternative methods, livestock, native lands, natural waterways, seed dispersal, seeding, wildlife}, author = {J.R. Barrow and Kris Havstad and Gibbens, Robert P. and Donaldson, P.} } @proceedings {51649, title = {Organogenesis and shoot-tip multiplication from tissue cultures of Atriplex species}, year = {1989}, month = {1989}, pages = {37-39}, publisher = {USDA Forest Service, GTR-INT 256}, address = {Logan, UT}, abstract = {

Roots and shoots were successfully grown from callus cultures of Atriplex canescens and A.griffithsii in some experiments. Attempts to replicate organogenesis in callus or liquid cultures from these species and in A. acanthocarpa, A. confertifolia, and A. polycarpa were unsuccessful, indicating that specific genetic or cultural requirements were necessary for induction. Shoot-tips were multiplied rapidly after two months in culture from diploid (2x), tetraploid (4x), and hexaploid (6x), plants and from three different collections of 4x populations. Shoot-tip multiplication is a promising method of mass propagation of \ specific genotypes of Atriplex species.

}, url = {/files/bibliography/311.pdf}, author = {J.R. Barrow} } @proceedings {51708, title = {The potential use of animals for the dispersal and establishment of native forage plants}, year = {1988}, month = {1988}, pages = {121}, author = {J.R. Barrow} } @article {51762, title = {The effects of chromosome number on sex expression in Atriplex canescens}, journal = {Botanical Gazette}, volume = {148}, number = {3}, year = {1987}, month = {September 1987}, pages = {379-385}, abstract = {

Native diploid, tetraploid, and hexaploid populations of Atriplex canescens were surveyed in southern New Mexico and west Texas. Female to male ratios were approximately equal in diploid populations and female-biased in tetraploid and hexaploid populations. Tetraploids in New Mexico and Texas differed from northern populations with more male and fewer monoecious plants. Hexaploids appeared to have slightly fewer female plants than tetraploids during flowering, but during the winter there were 6\%-20\% more seed-bearing plants because of the high frequency of monoecious plants. The three cytotype populations generally fited expected ratios using an X, Y sex-determining model. Monoecious diploid plants cannot be explained by the genetic model. Two types of monoecious expressions were observed, and possible genetic mechanisms are discussed.

}, url = {/files/bibliography/310.pdf}, author = {J.R. Barrow} } @article {51813, title = {The conditions required to isolate and maintain viable cotton (Gossypium hirsutum L.) microspores}, journal = {Plant Cell Reports}, volume = {5}, year = {1986}, month = {1986}, pages = {405-408}, abstract = {

Cultural systems developed for the successful production of haploid plants from anther and microspore culture of a number of species are lethal to cotton microspores. Components of these systems were examined individually and in simple combinations to determine their specific effect on cotton microspore viability during isolation and culture. An organically buffered pH of 7.0 was critical for survival. The addition of potassium salts, near standard concentrations used for other species, enhanced survival and the cytoplasmic appearance of isolated microspores. Severe toxicity resulted from ammonium, calcium and magnesium salts, and these ions were tolerated only at very low concentrations. Iron, glutamine, serine, inositol, vitamins, and trace minerals were generally not detrimental to microspores at standard concentrations. An isolation and cultural maintenance system was developed that yields large quantities of healthy, viable cotton microspores. This initial step allows for further research in inducing cotton microspores to divide and undergo embryogenesis.

}, doi = {10.1007/BF00269627}, url = {/files/bibliography/710.pdf}, author = {J.R. Barrow} } @proceedings {51812, title = {Regeneration of plants from two species of saltbush, Atriplex canescens and A. griffithsii}, year = {1986}, month = {1986}, pages = {178}, keywords = {A. griffithsii, Atriplex canescens, plants, regeneration, saltbush}, author = {J.R. Barrow} } @article {51935, title = {Comparisons among pollen viability measurments methods in cotton}, journal = {Crop Science}, volume = {23}, year = {1983}, month = {July-August 1983}, pages = {734-736}, keywords = {cotton, pollen, viability}, url = {/files/bibliography/99-010.pdf}, author = {J.R. Barrow} } @article {52029, title = {A new concept in assessing cotton pollen germinability}, journal = {Crop Science}, volume = {21}, year = {1981}, month = {May-June 1981}, pages = {441-443}, keywords = {cotton, germinability, pollen}, url = {/files/bibliography/99-009.pdf}, author = {J.R. Barrow} } @article {52201, title = {A homozygous interspecific F2 hybrid of Gossypium barbadense x gossypium hirsutum via the semigametic haploid method}, journal = {Crop Science}, volume = {16}, year = {1976}, month = {May-June 1976}, pages = {441-442}, keywords = {haploid, hybrid, semigametic}, url = {/files/bibliography/99-008.pdf}, author = {J.R. Barrow and H. K. Chaudhari} } @article {52224, title = {Somatic crossing over as a cause of intergenome translocations in haploid cotton}, journal = {The Journal of Heredity}, volume = {66}, year = {1975}, month = {1975}, pages = {277-280}, keywords = {cotton, haploid, intergenome, somatic}, url = {/files/bibliography/99-006.pdf}, author = {J.R. Barrow and M.P. Dunford} } @article {JRN54837, title = {Gl28-A New Allele for Pigment Glands in Cotton1}, journal = {Crop Science}, volume = {14}, year = {1974}, month = {March 1974}, pages = {325-326}, chapter = {325}, abstract = {

A new gland phenotype was observed in cotton (Cossypium hirsutum L.) segregating for Gl2 and Gl3. A genetic analysis was conducted to determine the inheritance of this character. It was found that the gene responsible was allelic to Gl2. The new allele was designated Gl28. Gl28 in the homozygous condition (Gl28Gl28 gl3gl3) imparts reduced gland density in the cotyledons, as compared to Gl2 or Gl3, with apparent normal gland distribution in the stems and petioles.

}, keywords = {Allelism, Insect resistance, Seed gossypol}, url = {https://dl.sciencesocieties.org/publications/cs/pdfs/14/2/CS0140020325}, author = {J.R. Barrow and D. D. Davis} } @article {JRN54836, title = {Somatic crossing over as a cause of chromosome multivalents in cotton}, journal = {Journal of Heredity}, volume = {65}, year = {1974}, month = {1974}, pages = {3-7}, chapter = {3}, abstract = {

Occasional somatic pairing of homologous chromosomes was observed in some plants and animals shortly after the turn of the century. There have been many other examples of pairing in succeeding years; where genetic markers were available for analysis, theory have provided evidence of somatic recombination. Stern19 observed single and twin spots of homozygous somatic tissue on wild-type background of Drosophilia heterozygous for specific marker genes. He established that somatic crossing over occurred in the four-strand stage and was genetically equivalent to meiotic crossing over. Jones12 suggested that spotting observed in corn tissues could be explained by somatic paring and crossing over. Vig22 reported genetic evidence of somatic crossing over as a course of twin spot in soybeans, heterozygous for incompletely doming gene Y11 for foliage color. He noted increased frequency of twin spots after treatment with chemicals known to allow rejoining of chromosomes. We2 observed twin spots in the leaves of homozygous cotton plants and considered somatic crossing over between homoeologous chromosomes as a more plausible explanations than somatic nondisjunction. In the early 1950{\textquoteright}s, geneticists working with several genera of imperfect fungi reported genetic recombination, concluding that somatic pairing of homologous chromosomes must occur.\  Westergaard concluded "that somatic crossing over that results in genetic recombination can only occur in cells having genetic recombination can only occur in cell having somatic pairing" (see Brown5 p,61). Gruberg9 stated "the cumulative weight of evidence makes a strong case for the existence of somatic crossing over in laboratory rodents." Holliday11 determined that somatic pairing of homologues occurs during interphase of the same time DNA is replicated.

}, doi = {10.1093/oxfordjournals.jhered.a108451}, author = {J.R. Barrow and M.P. Dunford} } @article {52292, title = {Twin spots on leaves of homozygous cotton plants}, journal = {The Journal of Heredity}, volume = {64}, year = {1973}, month = {1973}, pages = {222-226}, keywords = {cotton, homozygous}, url = {/files/bibliography/99-005.pdf}, author = {J.R. Barrow and H. K. Chaudhari and M.P. Dunford} } @article {52356, title = {Meiosis and pollen development in haploid cotton plants}, journal = {Journal of Heredity}, volume = {62}, number = {3}, year = {1971}, month = {May-June 1971}, pages = {139-141}, keywords = {cotton, haploid, Meiosis, pollen}, url = {/files/bibliography/99-007.pdf}, author = {J.R. Barrow} } @article {52383, title = {Critical requirements for genetic expression of verticillium wilt tolerance in acala cotton}, journal = {Phytopathology}, volume = {60}, number = {3}, year = {1970}, month = {March 1970}, pages = {559-560}, keywords = {acala, cotton, verticillium}, url = {/files/bibliography/99-004.pdf}, author = {J.R. Barrow} } @article {52382, title = {Heterozygosity in inheritance of verticillium wilt tolerance in cotton}, journal = {Phytopathology}, volume = {60}, number = {2}, year = {1970}, month = {February 1970}, pages = {301-303}, keywords = {cotton, heterozygosity, inheritance, verticillium}, url = {/files/bibliography/99-003.pdf}, author = {J.R. Barrow} }