杨维才研究组Nature子刊解析植物细胞膨压调控机制

　　

  膨压普遍存在于植物细胞，与生长发育密切相关，但对其调控的分子机制了解非常有限。中国科学院遗传与发育生物学研究所杨维才研究组通过对植物花粉管进行研究，发现了一个影响花粉管体内生长的突变体turgor regulation defect 1 (tod1)，其花粉管内钙离子浓度下降，在花柱内生长缓慢，不能及时有效地从花柱道中穿出，导致部分雄性不育；同时，该突变体还表现出气孔关闭失调，对植物激素ABA不敏感。对体外萌发花粉管的模拟压力环境生长实验和膨压测定显示突变细胞膨压增加，说明TOD1基因参与花粉管和气孔保卫细胞的膨压调控。

   TOD1基因编码一个高尔基体蛋白，在花粉管和角果表皮的保卫细胞中特异性表达；进一步研究表明TOD1具有碱性神经酰胺酶活性，它通过调节细胞内鞘氨醇及其下游活性分子——磷酸鞘氨醇的量和钙信号来调控细胞的膨压。

    该研究揭示了鞘脂类物质在花粉管膨压调节中的重要作用，于1月16日在线发表在Nature Communications (doi:10.1038/ncomms7030)上。杨维才研究组的陈立余博士为该论文的第一作者。该研究得到了科技部“生殖与发育”重大研究计划和国家自然科学基金的资助。

原文摘要：

The Arabidopsis alkaline ceramidase ​TOD1 is a key turgor pressure regulator in plant cells

Turgor pressure plays pivotal roles in the growth and movement of walled cells that make up plants and fungi. However, the molecular mechanisms regulating turgor pressure and the coordination between turgor pressure and cell wall remodelling for cell growth remain poorly understood. Here, we report the characterization of Arabidopsis ​TurgOr regulation Defect 1 (​TOD1), which is preferentially expressed in pollen tubes and silique guard cells. We demonstrate that ​TOD1 is a Golgi-localized alkaline ceramidase. ​tod1 mutant pollen tubes have higher turgor than wild type and show growth retardation both in pistils and in agarose medium. In addition, ​tod1 guard cells are insensitive to ​abscisic acid (​ABA)-induced stomatal closure, whereas ​sphingosine-1-phosphate, a putative downstream component of ABA signalling and product of alkaline ceramidases, promotes closure in both wild type and ​tod1. Our data suggest that ​TOD1 acts in turgor pressure regulation in both guard cells and pollen tubes.