Submitted to: PLoS One
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 26, 2013
Publication Date: September 9, 2013
Citation: Niogret, J., Epsky, N.D., Schnell Ii, R.J., Kendra, P.E., Heath, R.R. 2013. Terpenoid variations within and among half-sibling avocado trees, Persea americana Mill. (Lauraceae). PLoS One. 8(9):e73601. Interpretive Summary: Variation of chemicals found among different parts of a tree may influence the selection of insect herbivores within and among potential host trees. Terpenoid chemicals are often responsible for the insect’s attraction toward their host plant. Understanding the patterns of volatile terpenoid chemicals within and among trees is a very important step for understanding of the vulnerability of trees to insect attack. Therefore, scientists at SHRS analyzed the chemical patterns of volatile emissions from the cambium of the trunk to the leaves through different branch diameters, among genetically related avocado trees (full and half-siblings). The chemical profiles from trunks and the proximal ends of branches tended to separate from the chemical patterns from the distal ends of branches, petioles and leaves. This would explain differential attractiveness to wood-boring insects and resultant patterns of attack. Chemical patterns also provided good separations among full and half sibling avocado trees. Thus, chemotaxonomy using those types of chemical profiles could be used in conjunction with genetic analysis to further understand family groupings among avocado trees. This would provide a cost-effective tool to augment genetic analysis of this important food crop.
Technical Abstract: Variation of plant chemical phenotypes in a population can be explained by a combination of genetic, developmental and environmental factors. The age structure, environmental heterogeneity, and the limits in gene flow in a natural population will determine the variability and the spatial structure of the secondary chemistry landscape of plants. Chemical analysis were done using GC-MS to describes the spatial patterns of chemical variations in avocado cambium (bark and cambial layers) from the trunk to the leaves through different branch diameters, to determine the qualitative and quantitative chemical differences within and among avocado trees (Persea americana) at the same developmental stage and grown under the same outdoor conditions. Microsatellite analyses were done to link the genetic relationship to the chemical variability among those trees. We discuss the results in relation to the discrimination process used by wood-boring insects for site-selection on host trees.