荒漠植物红砂染色体倍性变异类型及其干旱适应性研究

Study on drought resistant adaptability of desert plants is a focus topic of current ecological research in arid regions. It is found that rich polyploidy plants are distributed in Arid Regions of Northwest China, but the ecological and adaptive significance of the polyploidization of plants remains under-investigated, especially that of desert plants has never been examined. This project is to study a desert plant Reaumuria soongorica (Pall.) Maxim, which is widely distributed in arid and semi-arid regions in northwest of China. The research work will be carried out on the characteristics of chromosome ploidy variation of R. soongorica populations under different drought environments, the physiological mechanisms and transcriptome analysis of various ploidy response to drought stress used by the technologies of root-tip squashed, plant physiology testing and stable carbon isotope analysis, transcriptome sequencing, digital gene expression analysis and quantitative PCR detection (QPCR). Its purpose is to explore the types of chromosome ploidy variation, the frequency of polyploidization of R. soongorica populations and the size of drought resistant capability of each ploidy, to solve the correlation of ploidy variation of R. soongorica, the aridity index and the soil water content and the drought-resistant ability of each ploidy, and to reveal that polyploidization of R. soongorica is an adaptive strategy to drought stress. In addition, it is further to explore the physiological and molecular mechanism of each ploidy of R. soongorica adaptation to drought stress. This project will provide a scientific basis for knowing the drought resistant adaptability of R. soongorica.

荒漠植物干旱适应性研究是当前干旱区生态学研究的热点。我国西北干旱区分布着丰富的多倍体物种，但植物尤其荒漠植物多倍化的生态适应意义仍不清楚。本研究以广泛分布于我国西北干旱区典型荒漠植物—红砂为研究对象，利用染色体压片、生理检测、同位素分析、转录组测序、数字基因表达谱分析及定量QPCR检测技术，开展不同干旱环境下红砂居群倍性变异特征、各倍性抗旱生理机制和转录学研究，了解不同干旱环境下红砂居群倍性变异类型、多倍化频率和各倍性抗旱能力的强弱，解决倍性变异与干燥度、土壤水分及抗旱能力之间的关系，揭示红砂多倍化是对干旱胁迫环境适应性分化的科学问题，并进一步揭示红砂各倍性适应干旱的生理机制和分子机制，为认识红砂干旱适应性奠定科学基础。

荒漠植物干旱适应性研究是当前干旱区生态学研究的热点。我国西北干旱区分布着丰富的多倍体物种，但植物特别是荒漠植物多倍化的生态适应意义仍不清楚。.针对荒漠植物红砂物种广泛分布于我国西北干旱区且具有不同倍性，本研究选取了6个不同干燥梯度研究区域了22个红砂居群，完成了对这六个研究区域气象资料的收集，22个居群样地土壤水分和盐分的检测、野外植株形态调查、花粉检测、染色体检测；对干旱胁迫下红砂二倍体和三倍体进行了生理指标及碳同位素的检测以及定量QPCR的检测，获取了以下一些研究结果。.红砂属于复合多倍体，红砂物种不仅有二倍体、三倍体，还有四倍体和六倍体多种细胞型，且同一居群存有多种倍性，也有居群由单一倍性二倍体构成。红砂多倍化频率和花粉变异率与区域干旱指数及温度有关，表现为环境越干旱，温度越低，红砂多倍性越高，越复杂。野外同生境下，红砂生长表征体现为二倍体植株叶片小，多倍体植株叶片大。野外同居群红砂光合差异明显，红砂气孔导度三倍体是二倍体的1.57倍、光合强度三倍体比二倍体强。野外自然生长的红砂碳同位素水平明显区别于培育种，野外样品碳同位素偏正，且二倍体和多倍体在同位素组成上不表现差异；红砂二倍体和三倍体都通过累积脯氨酸、蔗糖以及提高酶SOD、APX活性来适应干旱胁迫环境，但三倍体表现的能力更强，更耐旱。干旱适度胁迫环境下，红砂二倍体和三倍体脯氨酸合成基因RsP5CS2和RsP5CS1表达量都显著增加，且RsP5CS2的变化更明显，二倍体提高了7倍，三倍体提高了11倍。RsP5CS2基因表达峰值三倍体是二倍体的2.3倍，说明三倍体能提高脯氨酸合成基因的表达来抵抗干旱，其抗旱能力更强。.本研究认识到红砂是属于复合多倍体物种，阐明了多倍化频率与干旱指数和温度正相关，比较了三倍体的抗旱能力比二倍体强，揭示了红砂多倍化是对干旱胁迫环境的一种适应性分化，并进一步探究了红砂二倍体和三倍体适应干旱的生理机制和分子机制，这些研究结果为认识红砂干旱适应性奠定科学基础。.