Epicuticular Fatty Acid, Fatty Alcohol, and Alkane Contents of Bloom and Bloomless Sorghum ‘Redbine 60’ Leaves1

Abstract

Bloom and bloomless sorghum, Sorghum bicolor (L.) Moench, ‘Redbine 60’ are near isogenic lines differing in the presence or absence of a white, powdery‐appearing epicuticular leaf wax which influences plant water relations and animal utilization and whose genetic control and morphological characteristics have been published. Chemical evaluations of bloom and bloomless leaf epicuticular waxes are absent. Waxes were extracted with chloroform, esterified, separated into classes via thin‐layer chromatography, and quantitated via gas‐liquid chromatography utilizing polar and non‐polar columns and relative response curves from pure standard compounds. In leaves of equal density, leaves of the bloomless near‐isogenic line had epicuticular fatty acid, fatty alcohol, and alkane contents that were 73, 118, and 1%, respectively, of those constituents on bloom leaves. There was a 57% reduction on the bloomless leaf of total fatty acids + fatty alcohols + alkanes compared to the bloom leaf. Fatty alcohols longer than C20 were absent from the epicuticular wax of the bloom line. Alkane contents longer than C32 were essentially absent from the bloomless line while the most prevalent alkanes present on the bloom line were C35‐C37.