中国特有濒危孑遗植物水杉种子活力快速丧失的生理生态机制

Seed vigor and ageing is one of the hot topics in the field of seed biology research. However, few studies have been made on the change rule of vigor and aging mechanism of wild plant seeds under natural conditions by far. But, these researches are of great significance for population regeneration, community succession and ecological restoration, especially for the protection of endangered species. Metasequoia glyptostroboides is an endangered relict plant native to China. Although it has been successfully introduced in large numbers at home and abroad, the natural regeneration of its native populations has been difficult, and the endangered problem remains unsolved, and little is known about the endangered mechanism. Previous studies showed that Metasequoia glyptostroboides seeds have low vigor and are prone to rapid loss. We believe that the characteristic of low seed vigor and rapid loss of seed vigor in Metasequoia glyptostroboides is probably one of the main reasons for its endangered status. In this study, fresh mature Metasequoia glyptostroboides seeds will be subjected to an artificial accelerated ageing treatment, a natural ageing treatment and an hydration-dehydration cycling treatment simulating the wet-dry cycling resulted from rainfall in the natural conditions, and then the seeds with different vigor level will be obtained, subsequently germination test, electrical conductivity measurement, microscopic observation of cell structure, antioxidative analysis, transcriptomics and proteomics analysis will be carried out in order to find out the physiological and ecological mechanism of rapid loss of seed vigor in Metasequoia glyptostroboides, and to provide some theoretical knowledge for the conservation of Metasequoia glyptostroboides and other similar endangered gymnosperms.

种子活力和老化是种子生物学研究的热点之一。然而，目前对野生植物种子在自然条件下的活力变化规律及老化机理却鲜有研究，而这方面研究对于种群更新、群落演替和生态恢复等却意义重大，尤其是对于濒危植物的物种保护。我国特有濒危植物水杉虽已在国内外大量引种，但其原生种群自然更新困难，濒危尚未解除，对其濒危机制也知之甚少。研究表明，水杉种子活力低，且易丧失，与其原生种群更新困难的现状相一致。因此我们认为，水杉种子活力低且易快速丧失很可能是其濒危的主要原因之一。本研究以新鲜成熟水杉种子为材料，通过人工加速老化处理、户外自然老化处理，及定量模拟其野外因降雨等因素而反复经历干-湿循环的吸湿-回干循环处理，以获得活力不同的种子，随后依次进行萌发测试、电导率测定、细胞显微结构观察、抗氧化分析、转录组学与蛋白质组学分析等试验，以期探明水杉种子快速丧失的生理生态机制，为水杉及其他类似濒危裸子植物的保护提供理论依据。

我国特有濒危植物水杉虽已在国内外大量引种，但其原生种群自然更新困难，濒危尚未解除，对其濒危机制也知之甚少。研究表明，水杉种子活力低，且易丧失，与其原生种群更新困难的现状相一致。因此我们认为，水杉种子活力低且易快速丧失很可能是其濒危的主要原因之一。本研究以新鲜成熟水杉种子为材料，通过人工加速老化处理、户外自然老化处理，及模拟其野外因降雨等因素而反复经历干-湿循环的吸湿-回干循环处理，以获得活力不同的种子，随后依次进行萌发测试、电导率测定、细胞显微结构观察、抗氧化分析、转录组学与蛋白质组学分析等试验，以期探明水杉种子快速丧失的生理生态机制，为水杉及其他类似濒危裸子植物的保护提供理论依据。结果表明：（1）脆弱的抗氧化防御系统，线粒体等关键细胞器的过早解体很可能是水杉种子在老化过程中活力快速丧失的主要原因，而“内质网蛋白质加工进程”很可能也起着关键的作用；（2）lncRNA_00185 很可能是一个抗老化关键成分，与 miR167 (a, b, c, d) 之间存在竞争，并且与植物老化相关，共同调控 RCD1 (Radical-induced Cell Death 1) 基因的表达，促进活性氧物质的平衡并提高种子的抗老化能力；（3）人工吸湿—回干循环处理下，相较于饱和吸胀后回干处理，不饱和吸胀后回干处理，使种子受到的伤害更大， 活力丧失更快速；（4）林下露天处理的种子之所快速丧失活力和生活力，应该就是由露天情况下反复降雨-天晴 导致种子反复经历不饱和吸胀后回干循环所致。本项目初步阐明了水杉原生种群种子活力情况，及其在自然条件下的活力丧失机制，为水杉原生种群的科学保护奠定了理论基础。