|Title||Influence of plant material handling protocols on terpenoid profiles of one-seed Juniper saplings|
|Publication Type||Journal Article|
|Year of Publication||2006|
|Authors||Utsumi, SA, Cibils, AF, Estell, RE, Wang, YF|
Accurate estimation of one-seed juniper (Juniperus monosperma (Englem). Sarg.) intake by goats and sheep often requires harvesting, transporting, and storing plant material that is later used in pen experiments. Such manipulation could alter terpenoid profiles and modify herbivory levels significantly. We used gas chromatography mass spectrometry (GC/MS) to analyze the terpenoid profile of the ethanol extract of leaves of small and large one-seed juniper saplings subjected to three different handling protocols. Plant materials were either: a) placed on dry ice after clipping and then at -80º C until analysis (Control); b) stored at ambient temperature during the first 24 hours and then frozen; or c) stored at ambient temperature during the first 24 hours, and then stored at 8ºC for 3 weeks. Juniper saplings contained a mixture of 51 terpenoids, three of which were unknown compounds. Only 14 terpenoids accounted for 95% of the total volatiles extracted. Alpha-pinene was the most abundant compound, accounting for 65% of total terpenoid concentration. Total terpenoid content did not differ among handling protocol treatments (Control: 21,682.19 ±1,424.72 'g g-1 DM; Frozen after 24 h: 19,553.63 ±1,081.88 'g g-1 DM; Refrigerated for three weeks: 18,799.89 ±1,126.03 'g g-1 DM). Handling protocols appeared to induce only slight variations in a small number of minor terpenes. We detected large among-plant variation in terpenoid profiles that was not fully explained by sapling size. This study suggests that juniper feeding trials can be simplified using plant material stored at 8ºC for three weeks without significant alteration of terpenoid profiles. Among-plant variation in chemical composition, however, must be considered in pen feeding trials.