Targeted Lipidomics Studies Reveal that Linolenic Acid Promotes Cotton Fiber Elongation by Activating Phosphatidylinositol and Phosphatidylinositol Monophosphate Biosynthesis.
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 species. The genes encoding fatty acid desaturases (Δ(15)GhFAD), 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. Exogenously 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 ineffective. 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 GhΔ(15)FAD, 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.
['Liu|Gao-Jun|GJ|', 'Xiao|Guang-Hui|GH|', 'Liu|Ning-Jing|NJ|', 'Liu|Dan|D|', 'Chen|Pei-Shuang|PS|', 'Qin|Yong-Mei|YM|', 'Zhu|Yu-Xian|YX|']
D053898:Biosynthetic Pathways D004043:Dietary Fiber D018506:Gene Expression Regulation, Plant D003368:Gossypium D018129:Phosphatidylinositol Phosphates D010716:Phosphatidylinositols D010940:Plant Proteins D017962:alpha-Linolenic Acid
fiber elongation phosphatidylinositol phosphatidylinositol monophosphate Gossypium hirsutum glycerophospholipid profiling mass spectrometry