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早期水生植物成功登陆并演化为陆生植物，为后期被子植物的繁荣做了重要铺垫。植物适应陆地环境与角质层的形成密切相关，而作为角质层组成部分，植物表皮蜡质是植物抵御环境胁迫的重要屏障。特别是在缺水的条件下，相关基因的表达能够促使蜡质的合成增加，从而减少植物遭受干旱带来的伤害。
近日，中国科学院昆明植物研究所杨永平研究员带领的植物基因组演化与基因功能发掘团队以蔓菁为研究对象，结合不同基因型的蔓菁品种，通过生理生化和转录组学的方法，解析了蔓菁叶片蜡质参与干旱胁迫的反应机制。结果发现，有蜡粉的蔓菁品种比无蜡粉的品种有更强的耐旱性，通过PacBio和Illumina测序检测到有蜡粉品种的BrrWSD1-X2基因存在特异的可变剪切体。利用酵母突变株进行基因异源表达发现，BrrWSD1-X2比BrrWSD1-X1具有更强的蜡酯合成能力。研究推测，有蜡粉的蔓菁品种中，BrrWSD1 DNA第三段内含子的T-to-C转换和更多TA重复可能导致其剪接识别效率的降低，促进BrrWSD1-X2剪切体的出现。研究结果为阐明WSD1基因参与植物蜡酯合成以及蔓菁叶片蜡酯参与干旱胁迫的反应机制提供了新证据。
研究成果以“A splice variant of BrrWSD1 in turnip (Brassica rapa var. rapa) and its possible role in wax ester synthesis under drought stress”为题在线发表于Journal of Agricultural and Food Chemistry。本研究得到国家自然科学基金、中国科学院西部之光以及中国科学院“十三五”信息化规划等项目资助。
Abstract
Cuticular wax accumulation in plants contributes to drought tolerance. Here, we compared the drought levels on two varieties with different genotypes in turnip (Brassica rapavar. rapa) and found that the drought tolerance was higher in the waxy KTRG-B48a than in the wax-free KTRG-B48b. A combination of PacBio and Illumina sequencing analyses revealed that differential transcripts were mainly enriched in the wax synthesis pathway, and a splice variant (BrrWSD1-X2) was identified in the waxy KTRG-B48a.BrrWSD1-X2had a stronger ability to synthesize wax esters thanBrrWSD1-X1using heterologous expression in yeast (Saccharomyces cerevisiae) mutant H1246a. Then, we speculated that the T to C transversion of the third intron and the higher number of TA repeats in the third intron ofBrrWSD1DNA in the waxy KTRG-B48a may result in a lower efficiency of splicing recognition of the third intron, resulting in the emergence ofBrrWSD1-X2in waxy varieties.
来源：中国科学院昆明植物研究所
