@article {49847,
	title = {Within-plant distribution of volatile compounds on the leaf surface of Flourensia cernua},
	journal = {Biochemical Systematics and Ecology},
	volume = {48},
	year = {2013},
	month = {01/2013},
	pages = {144-150},
	chapter = {144},
	abstract = {<p>We are using Flourensia cernua as a shrub model to study the role of terpenes on intake by livestock. Two experiments were conducted to examine distribution of volatile chemicals within a plant in an effort to minimize sample variability. In Exp. 1, leaves (current year\&$\#$39;s growth) were collected from 20 tarbush plants. Two leaders were sampled from each of three positions (outer canopy, subcanopy, and basal) in all four quadrants (based on ordinal direction). In Exp. 2, 10 leaders of current year\&$\#$39;s growth were removed from another 20 plants. Leaders were collected from the outer canopy of each quadrant and separated into thirds before removing leaves, thereby creating three leaf age categories. Volatile compounds were extracted with ethanol and analyzed with gas chromatography/mass spectrometry. Ninety-four chemicals (including 15 unknowns) were present on the leaf surface of F. cernua. Although 14 and 21 compounds differed (P \&lt; 0.05) among quadrants in Exp. 1 and 2, respectively, no consistent quadrant effect was detected in either study. Leaf position differed (P \&lt; 0.05) for 52 chemicals in Exp. 1 but outer canopy and subcanopy leaves differed for only 10 compounds. In Exp. 2, 63 compounds differed among leaf age categories. Immature leaves contained greater concentrations of 46 chemicals (P \&lt; 0.05) than moderate or mature age categories, but moderate and mature leaves differed for only seven compounds. Estimated total concentration (i.e., cumulative concentration of all compounds) was not affected by leaf position but varied among leaf age categories (P \&lt; 0.05; immature \&gt; moderate \&gt; mature). Differences in leaf position were attributed about equally to mono- and sesquiterpenes, whereas leaf age was affected to a greater extent by sesquiterpenes. Leaf position and maturity both affect terpene concentration and sampling variability for tarbush. However, little difference was detected between subcanopy and canopy positions. Thus, by avoiding basal sprouts and sampling from the mid-point of current year\&$\#$39;s growth, sampling variation should be minimal.</p>
},
	keywords = {Flourensia cernua, leaf age, plant secondary metabolites, terpenes, volatiles, within-plant distribution},
	doi = {10.1016/j.bse.2012.11.020},
	url = {/files/bibliography/13-002.pdf},
	author = {Richard E. Estell and D. K. James and E.L. Fredrickson and D.M. Anderson}
}
@conference {49943,
	title = {Distribution of antiherbivory compounds in Flourensia cernua},
	booktitle = {American Society of Animal Science Joint Annual Meeting},
	year = {2011},
	month = {07/2011},
	publisher = {Journal of Animal Science},
	organization = {Journal of Animal Science},
	address = {New Orleans, LA},
	abstract = {Flourensia cernua is serving as a shrub model to study the influence of terpenes on intake by livestock at this location. Two studies (n=20 plants per study) were conducted to examine within plant distribution of volatile compounds to improve sampling protocol. Leaves from 3 positions (outer canopy, subcanopy, and basal) were collected from 4 quadrants (based on ordinal direction) in Exp. 1. Leaves were removed from 2 leaders of current year\&$\#$39;s growth for each position in each quadrant. In Exp. 2, 10 leaders of current year\&$\#$39;s growth were collected from the outer canopy in each quadrant and 3 leaf age categories were formed by separating leaders into thirds and removing leaves. Chemicals were extracted from 5 leaves in duplicate with ethanol and analyzed with gas chromatography/mass spectrometry. Data were log transformed and analyzed by univariate ANOVA and means were separated using Tukey\&$\#$39;s HSD. Ninety-three volatile compounds (including 15 unknowns) were present on the leaf surface of F. cernua. Only 7 compounds (including 3 unknowns) in Exp. 1 and 9 in Exp. 2 differed (P\&lt;0.05) among quadrants, and no consistent effect of quadrant was observed in either study. In Exp. 1, 31 compounds differed (P\&lt;0.05) among leaf positions, but outer canopy and subcanopy leaves did not differ for any compound. Basal leaves contained greater concentrations than outer canopy and subcanopy leaves for 10 compounds, and less than the other 2 positions for 10 compounds. Thirty-two compounds differed for leaf age in Exp. 2, with immature leaves containing greater concentrations than mature leaves for 30 compounds and greater than the middle age category for 26 compounds (P\&lt;0.05). Total concentration (cumulative concentration of all compounds) did not differ among leaf positions but differed for leaf age (greater in immature than mature leaves; P\&lt;0.05). Compounds that differed in Exp. 1 were represented about equally by mono- and sesquiterpenes, whereas compounds affected by leaf age were predominantly sesquiterpenes (only 3 of 32 were monoterpenes). Both leaf position and age affect terpene concentrations and sampling variability in this shrub.},
	keywords = {chemical distribution, leaf age, terpenes},
	author = {Richard E. Estell and E.L. Fredrickson and D. K. James and D.M. Anderson}
}
