The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
The State Key Laboratory of Protein and Plant Gene Research, College of Life Sciences, Peking University, Beijing 100871, China.
Mol Plant. 2015 Jun;8(6):911-21. doi: 10.1016/j.molp.2015.02.010. Epub 2015 Feb 28.
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.
从授粉后 10 天的快速伸长野生型棉花（Gossypium hirsutum）纤维、去除纤维细胞的野生型胚珠和同年龄的无绒无毛突变体胚珠中提取、分离和定量膜脂。纤维细胞中磷脂酰肌醇（PI）的含量明显高于两种胚珠样品，其中 PI 34:3 是最主要的物种。编码脂肪酸去饱和酶（Δ（15）GhFAD）、PI 合酶（PIS）和 PI 激酶（PIK）的基因以纤维偏好的方式表达。对磷脂酰肌醇单磷酸（PIP）的进一步分析表明，伸长纤维中 PIP 34:3 的含量比胚珠高四到五倍。外源性亚麻酸（C18:3）、大豆 L-α-PI 和含有 PIP 34:3 的 PIP 促进显著的纤维生长，而缺乏 C18:3 部分的肝 PI、亚油酸和 PIP 36:2 则完全无效。Carbenoxolone、5-羟色胺和wortmannin 的生长抑制作用分别被 C18:3、PI 或 PIP 逆转，表明 PIP 信号对于纤维细胞生长是必需的。此外，表达病毒诱导的基因沉默构建体的棉花植物，特异性抑制 GhΔ（15）FAD、GhPIS 或 GhPIK 的表达，导致明显的短纤维表型。我们的数据为深入研究 PI 和 PIP 在介导棉花纤维生长中的作用提供了基础。
