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Cuticular wax variants in a population of switchgrass (Panicum virgatum L.)

Author:
Weaver, Joshua M., Lohrey, Greg, Tomasi, Pernell, Dyer, John M., Jenks, Matthew A., Feldmann, Kenneth A.
Source:
Industrial crops and products 2018 v.117 pp. 310-316
ISSN:
0926-6690
Subject:
Panicum virgatum, abiotic stress, color, crystals, epicuticular wax, germplasm, leaves, phenotypic variation, scanning electron microscopy, waxes
Abstract:
Leaf cuticular waxes are known to influence both biotic and abiotic stress tolerances of plants. The objective of this work was to characterize the wax phenotypic diversity present in a population of 1849 switchgrass plants. We identified 92 visually distinct variant plants that possessed altered leaf glaucousness relative to the common standard type (ST), which exhibited a bluish-white (glaucous) leaf color. The variants could be grouped into three classes: 1) non-glaucous types (NG) that possessed a shiny green leaf surface, 2) reduced glaucous types (RG) that appeared less glaucous than ST, and 3) highly glaucous types (HG) that exhibited more intense bluish-white color than ST. Analyses of total cuticular wax content averaged over each of three NG (mean 304.79 ± 15.16 μg/dm2), RG (mean 533.33 ± 21.62 μg/dm2) and HG types (mean 1228.23 ± 45.74 μg/dm2) showed significant differences (P < 0.001) from three selected STs (mean 810.92 ± 30.57 μg/dm2). Analysis of wax composition among these selected types revealed that the C33 β-diketones were the most abundant wax compounds in all but NG types. Field emission scanning electron microscopy showed that abaxial leaf surfaces exhibited predominantly rod-shaped crystals, and adaxial surfaces exhibited predominantly plate-shaped wax crystals on all lines, except for NG that lacked wax crystals on the abaxial leaf surface. As a target for crop improvement, this study reveals that a large amount of variation for cuticle waxes exists within this switchgrass germplasm.
Agid:
5937047