复苏观赏植物垫状卷柏耐脱水机制研究

Resurrection plants with the remarkable desiccation tolerance can survive in extreme dehydration state, and recover to the normal growth by rehydration when the water is available. This miraculous phenomenon (i.e., from death to aliveness) makes the resurrection plants become a special group of ornamental plant resources. However, how the resurrection plants achieve the remarkable desiccation tolerance is still a basic biological question needed to be explored deeply. Resurrection fern-ally Selaginella with small genome size is a typical group of resurrection plants, which is a precious material for studying the mechanism of the desiccation tolerance. Unfortunately, related research for investigating the desiccation tolerance mechanism of this group is still absent. In order to reveal the molecular regulatory mechanism of the desiccation tolerance in S. pulvinata and discuss the similarities and differences between S. pulvinata and other groups of resurrection plants (i.e., bryophyte and angiosperm), S. pulvinata will be adopted as the materials in this study. Specifically, the observation of mesophyll cell ultrastructure, the collection of physiological and ecological data, the establishment and analysis of transcriptome database, the expression analysis and clone of genes related to the desiccation tolerance will be conducted under different relative water content (control, dehydration and rehydration). The result obtained will provide essential insights for the research on the desiccation tolerance mechanism and the discovery of drought tolerance genes in the resurrection plants. Moreover, it will also provide meaningful references for the research of the evolutionary biology, the physiological and ecological drought adaptability of the resurrection plants.

复苏植物具有极强耐脱水性，极端脱水时能维持生存，水分适宜时，通过再水化恢复正常生长，这种“死而复生”的神奇现象使复苏植物成为一类特殊的观赏植物资源，而复苏植物如何实现超强耐脱水性仍是一个亟待深入研究的生物学问题。拟蕨类卷柏属（Selaginella）复苏种类是复苏植物典型代表类群，基因组较小，是开展耐脱水性研究的宝贵材料，但该类群的耐脱水机制尚缺乏深入研究。本项目拟以垫状卷柏（S. pulvinata）为实验材料，对不同相对含水量下（对照、脱水及复苏）进行叶肉细胞超微结构观察、生理生态指标测定、转录组数据库构建与分析、耐脱水性相关基因表达分析与克隆，从而阐明垫状卷柏耐脱水性分子调控机制，探讨垫状卷柏与其他复苏类群（苔藓、被子植物）耐脱水机制异同。研究结果将对复苏植物耐脱水机制研究和耐旱基因资源挖掘具有重要意义，并为复苏植物进化生物学及其对干旱的生理生态适应性研究提供参考。

复苏植物垫状卷柏(Selaginella pulvinata)具有超强耐脱水性，赋予其“死而复生”的神奇能力，能够耐受长时间脱水，给予充足水分后能迅速恢复正常生长。项目组综合运用形态学、细胞学、生理生态学以及转录组学等手段对垫状卷柏耐脱水机制进行探究。综合分析显示，垫状卷柏全长转录组数据库共组装得到78,914个isoform，其中75,819个isoform (96.07%) 获得注释信息。以全长转录组数据为参考，二代转录组数据比对率为86.83~93.46%，脱水和复苏过程中共有17,934个差异表达基因。脱水时，垫状卷柏卷曲成球状以减小受光面积，保护中心区域。膨胀的叶绿体和线粒体以及空泡化在脱水细胞中发挥占位作用，避免了细胞塌陷和折叠。受光面积减少、PSⅡ失活以及光合作用基因的表达量下调有助于减少因过量光吸收导致的活性氧产生。抗氧化酶活性的增加以及相关基因的表达量上调将促进活性氧清除。渗透调节物质含量的增加和相关基因表达上调，以及保护性蛋白相关基因表达量上调均有助于减小脱水损伤。此外，由于脱水过程中ABA含量显著增加和相关基因的表达量上调，我们认为ABA信号通路可能在垫状卷柏耐脱水性中发挥重要作用。本研究初步阐释了垫状卷柏耐脱水机制，对植物耐旱育种具有重要意义。在本项目支持下，发表论文3篇，其中SCI论文2篇，获专利授权2项，项目组3人晋升副研究员，项目负责人获得博士学位，并获入选云南省中青年学术和技术带头人后备人才。