|Percival Jr, Albert|
|Williams, Howard - TEXAS A&M UNIVERSITY|
Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: January 9, 1997
Publication Date: N/A
Technical Abstract: The volatile monoterpenes and sesquiterpenes of Gossypium species are localized in the lysigenons pigment glands that contain gossypol in seed and distinguish the tribe Gossypieae. Concentrations of the volatile terpenes are greatest in very young leaves and bolls. Texas race stocks of G. hirsutum that show resistance to insects, are used in folk medicine or contain high concentrations of (+)-gossypol were surveyed for the quality of volatile terpenes in young leaves. Plants with unique volatile patterns were crossed and backcrossed to 'TAMCOT CAMD-E' to determine the genetic control of volatile terpene synthesis. The survey and genetic studies indicate that separate single genes (and probably terpene cyclases) control the synthesis of 1) ocimene and myrcene; 2) alpha- and beta-pinene and limonene; 3) alpha- and gamma-terpene and 2 unknown monoterpenes; 4) caryophyllene, humulene, and caryophyllene oxide; 5) gamma-bisabolene and beta-bisabolol; 6) alpha- and beta-selinene; 7) aromadendrene and spathulenol, and 8) a major unknown (located just before bisabolene in the GC profile) and 2 minor unknowns. In some cases there were distinct differences in the ratio of products formed by the same type of cyclase. For example, the ratio of pinenes to limonene were either about 10:1 or 3:1. This indicates that there are different alleles producing slightly different pinene cyclases. Similar variations were noted for caryophyllene: humulene ratios. Species of A genome and D genome cottons, which are probably the progenitors of the AD species were surveyed for volatile terpenes to determine possible origins of specific cyclase variations.