Evaluating Protective Terpenoid Aldehyde Compounds in Cotton (<i>Gossypium hirsutum</i> L.) Roots

Abstract

Cotton (Gossypium hirsutum L.) has epidermal glands containing terpenoid aldehyde (TA) compounds that protect the plant from pests and diseases. One TA, gossypol, has two forms (+) and (−) that are present in varying amounts. This study evaluated the variation in roots for TA compounds and how environment affected the levels of these compounds. Similar to seed, gossypol was the predominant TA in roots. No heliocides were detected with only trace amounts of other TAs, such as hemigossypolone or hemigossypol, detected in a few lines. Among the glanded lines, there were significant differences in gossypol content. Percent plus gossypol was consistently 4% -10% higher in roots than seed. One line, "Mac7", had 12 -14 ug/mg gossypol in roots and 18 ug/mg in seed as well as >90% (+) gossypol in both roots and seed. Unlike other tissues in glandless cotton, the roots of glandless lines consistently produced detectable amounts of gossypol with 77% to 82% in the (+) form. Multi-year field tests showed that although gossypol levels in the roots were more affected by insect pressure or other environmental conditions than seed, there was selectable variation in upland cotton for root gossypol content. Unlike other parts of a glandless plant, the roots retained a functioning biochemical pathway for gossypol production.

Effect of Chromosome Substitution from Alien Tetraploid Cotton Species in Upland Cotton on (+) and (-) Gossypol Enantiomer Levels in Cottonseed

“…Our result showing the significant effects of CS line and location and its interaction for (+) gossypol, (-) gossypol, and total gossypol percentage, has also been reported that, on average, G. barbadense has higher gossypol concentrations than G. hirsutum (Gadelha et al, 2014). Although gossypol, including the proportion of (+) and (-) gossypol production, is genetically controlled and varies between and within species (Percy et al, 1996), environmental conditions can affect the accumulation of gossypol (Percy et al, 1996;Scheffler, 2016;Stansbury et al, 1956). For example, Pons et al (1953) studied the effects of variety and environment in eight cottonseed varieties.…”

“…Throughout the plant, cotton is characterized by the presence of gossypol storage pigment glands that contain terpenoid aldehydes (Rathore et al, 2012). Gossypol is a phenolic compound produced by pigment glands distributed throughout plant, but concentrated in seeds (Alexander et al, 2008;Kenar, 2006;Rogers et al, 2002;Romano and Scheffler, 2008) and roots (Scheffler, 2016). Cottonseed contains several toxic chemicals as secondary metabolites, including gossypol, cinnamic acids, flavonoids, terpenoids, alkaloids, cyanohydrins, quinones, saponins, unsaturated lactones, benzoxazinones, allyl sulfides, thiocyanates, and polyacetylenes (Ingham and Harborne, 1976;Stoessl et al, 1976).…”

“…Gl2 and Gl3 were localized to the A12 and D12 chromosomes of G. hirsutum, respectively (Lee, 1965;Percy et al, 2015;Samora et al, 1994). Different combinations of dominant (Gl) and recessive (gl) alleles produced lesser number of glands with varying distribution in different parts of the plant at different stages of development (Gutierrez et al, 1972;Lee, 1965;McCarty et al, 1996;Mc-Michael, 1960;Scheffler andRomano, 2008, 2012). Considering the importance of pigment glands in cotton, genetic knowledge as well information about genetic variation of gossypol genes in the other tetraploid species is critical for the improvement of this trait in Upland cotton.…”

Chemical defense responses of upland cotton, Gossypium hirsutum L. to physical wounding

“…As previously mentioned, gossypol is predominant in seeds while hemigossypolone and heliocides are predominant in foliar glands (Scheffler, ). In the leaf samples, (+), (−)‐gossypol levels appeared to be low as expected, ranging from 0.11% to 0.61% (Figure a).…”

“…Upland cotton produces varying amounts of TAs in most parts of the plant including the leaf, boll, seed, boll hull, calyx, and root (Figure a) (Scheffler, ). The TA biosynthetic pathway is shown in Figure b (Benedict, Martin, Liu, Puckhaber, & Magill, ).…”