The membrane lipids from fast-elongating wild-type cotton （Gossypium hirsutum） fibers at 10 days post- anthesis, wild-type ovules with fiber cells removed, and ovules from the fuzzless-lintless mutant harvested at t...The membrane lipids from fast-elongating wild-type cotton （Gossypium hirsutum） fibers at 10 days post- anthesis, wild-type ovules with fiber cells removed, and ovules from the fuzzless-lintless mutant harvested at the same age, were extracted, separated, and quantified. Fiber cells contained significantly higher amounts of phosphatidylinositol （PI） than both ovule samples with PI 34：3 being the most predominant spe- cies. The genes encoding fatty acid desaturases （415GhFAD）, PI synthase （PIS） and PI kinase （PIK） were expressed in a fiber-preferential manner. Further analysis of phosphatidylinositol monophosphate （PIP） indicated that elongating fibers contained four- to five-fold higher amounts of PIP 34：3 than the ovules. Exog- enously applied linolenic acid （C18：3）, soybean L-α-PI, and PIPs containing PIP 34：3 promoted significant fiber growth, whereas a liver PI lacking the C18：3 moiety, linoleic acid, and PIP 36：2 were completely ineffec- tive. The growth inhibitory effects of carbenoxolone, 5-hydroxytryptamine, and wortmannin were reverted by C18：3, PI, or PIP, respectively, suggesting that PIP signaling is essential for fiber cell growth. Furthermore, cotton plants expressing virus-induced gene-silencing constructs that specifically suppressed Gh15FAD, GhPIS, or GhPIK expression, resulted in significantly short-fibered phenotypes. Our data provide the basis for in-depth studies on the roles of PI and PIP in mediating cotton fiber growth.展开更多
文摘The membrane lipids from fast-elongating wild-type cotton （Gossypium hirsutum） fibers at 10 days post- anthesis, wild-type ovules with fiber cells removed, and ovules from the fuzzless-lintless mutant harvested at the same age, were extracted, separated, and quantified. Fiber cells contained significantly higher amounts of phosphatidylinositol （PI） than both ovule samples with PI 34：3 being the most predominant spe- cies. The genes encoding fatty acid desaturases （415GhFAD）, PI synthase （PIS） and PI kinase （PIK） were expressed in a fiber-preferential manner. Further analysis of phosphatidylinositol monophosphate （PIP） indicated that elongating fibers contained four- to five-fold higher amounts of PIP 34：3 than the ovules. Exog- enously applied linolenic acid （C18：3）, soybean L-α-PI, and PIPs containing PIP 34：3 promoted significant fiber growth, whereas a liver PI lacking the C18：3 moiety, linoleic acid, and PIP 36：2 were completely ineffec- tive. The growth inhibitory effects of carbenoxolone, 5-hydroxytryptamine, and wortmannin were reverted by C18：3, PI, or PIP, respectively, suggesting that PIP signaling is essential for fiber cell growth. Furthermore, cotton plants expressing virus-induced gene-silencing constructs that specifically suppressed Gh15FAD, GhPIS, or GhPIK expression, resulted in significantly short-fibered phenotypes. Our data provide the basis for in-depth studies on the roles of PI and PIP in mediating cotton fiber growth.
