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.
The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
Gao-Jun
GJ
Liu
The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
Guang-Hui
GH
Xiao
The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
Ning-Jing
NJ
Liu
The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
Dan
D
Liu
The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
Pei-Shuang
PS
Chen
The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China. Electronic address: qinym@pku.edu.cn.
Yong-Mei
YM
Qin
The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
Yu-Xian
YX
Zhu
D053898:Biosynthetic Pathways; D004043:Dietary Fiber / Q000032:analysis; D018506:Gene Expression Regulation, Plant; D003368:Gossypium / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D018129:Phosphatidylinositol Phosphates / Q000096:biosynthesis*; D010716:Phosphatidylinositols / Q000096:biosynthesis*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D017962:alpha-Linolenic Acid / Q000378:metabolism*
D004043:Dietary Fiber; D018129:Phosphatidylinositol Phosphates; D010716:Phosphatidylinositols; D010940:Plant Proteins; D017962:alpha-Linolenic Acid
Gossypium hirsutum; fiber elongation; glycerophospholipid profiling; mass spectrometry; phosphatidylinositol; phosphatidylinositol monophosphate