条斑紫菜渗透压胁迫耐受相关eQTL定位及调控网络解析

Pyropia yezoensis, a scientifically and economically valueable seaweed, is the representative of marine seaweeds inhabited in the coastal intertidal zone. It is also an ideal model species for algae genomics and physiololgy of osmotic stress-tolerance studies. Though the physical and chemical enviroments of intertidal zone change dramatically along with the tide flood and ebb, P. yezoensis can thrive in this region, indicating that it can regulate itself and adapt to the enviromental stress. But till now, we know few about its mechanism on stress-tolerance. To obtain the ideal experimental materials, we collect the samples from different habitats in the intertidal field and also using the selected strain treated with the scientifically designed methods. One objective of this study is establishment of the measurement teniques and index system for evaluating the traits of osmotic stress-telorance. We will parse the P. yezonesis transcriptome and analyze the expression profile of the algae treated with high and low osmotic pressure. Then by comparing the the samples between the treated and the ones growing under normal conditions, we can identify the key genes responding to the stresses and affirm the key enviromental stress factors. Through this study, we will know the genes and pathway of P. yezoensis responsive to the osmotic stresses. We will screen the SNPs from the transcripts responsive to the changes of ostmotic pressure. Then the analysis of allele specific expression will be conducted. Finally, the eQTL of the major genes related to the traits of osmotic-telorance will be mapped. The results of this study not only benefit for further understanding the molecualr mechanism of P. yezoensis responsive to osmotic stress but also provide important information for breeding with maker assisted selection.

条斑紫菜（Pyropia yezoensis）既是重要的经济物种，也是红藻门的代表性物种。由于其具有极强的耐受渗透压胁迫的能力，成为研究渗透压胁迫响应和适应的理想材料。 本课题针对大型海藻渗透压胁迫响应和耐受分子机制研究的空白，以条斑紫菜为研究对象，检测渗透压胁迫条件下生理生化变化，构建渗透压胁迫耐受性评价指标体系；采用RNA-seq结合生物信息分析技术，鉴定响应渗透压胁迫的基因和重要代谢途径，分析基因表达调控因子，阐释渗透压胁迫响应调控网络；筛查渗透压胁迫相关基因单核苷酸多态性，分析等位基因表达特异性（ASE），定位渗透压胁迫耐受主效基因座位（eQTL）。以期深入了解条斑紫菜渗透压耐受性状的分子遗传机制，为条斑紫菜抗逆标记辅助选择育种（MAS）提供依据。

条斑紫菜（Pyropia yezoensis）既是重要的经济物种，也是红藻门及潮间带海藻的代表性物种。由于其具有极强的耐受渗透压胁迫的能力，成为研究渗透压胁迫响应和适应的理想材料。本课题以条斑紫菜为研究对象，检测渗透压胁迫条件下生理生化变化，构建渗透压胁迫耐受性评价指标体系；采用RNA-seq 结合生物信息分析技术，鉴定响应渗透压胁迫的基因和重要代谢途径，分析基因表达调控因子，阐释渗透压胁迫响应调控网络；筛查渗透压胁迫相关基因单核苷酸多态性，分析等位基因表达特异性，定位渗透压胁迫耐受主效基因座位。本研究为深入了解条斑紫菜渗透压耐受性状的分子遗传机制，为条斑紫菜抗逆标记辅助选择育种提供依据。.取得的主要成果：1、在国际上率先完成了条斑紫菜和坛紫菜全基因组精细图谱组装。条斑紫菜基因组大小108.2M，GC含量64.8%；contig数目1444个，N50 201.4kb；scaffold数目680，N50 337.7kb，错误率低于0.02%。坛紫菜基因组大小57.9M，GC含量达69.1%；contig数目1839个，N50 510.3kb；scaffold数目652，N50 912.7kb，错误率低于0.08%。条斑紫菜和坛紫菜基因组精细图谱的完成为紫菜遗传学和遗传育种奠定了坚实的基础。2、系统阐释了条斑紫菜耐受渗透压胁迫的分子机制，证明了其耐受渗透压胁迫机制复杂多样。在失水胁迫下发现5个与之密切相关的模块，其功能主要与蛋白质的加工合成过程、泛素介导的蛋白质水解过程以及维持细胞骨架相关。复水时发现2个与该胁迫条件密切相关的基因模块，主要富集在谷胱甘肽代谢、细胞色素P450介导的外源性物质代谢通路、内质网上蛋白质加工。此外，细胞信号转导，热激蛋白，二氧化碳浓缩机制等也发挥重要作用。3、实现了渗透压胁迫耐受性状的全基因组关联分析与QTL定位。通过重测序，鉴定了924,124个高质量的SNP位点和41,671个InDels，构建了一套高密度的条斑紫菜变异图谱，为条斑紫菜的育种研究提供了丰富的遗传标记。检测出4个显著相关的SNP位点，解释表型变异的23.68%- 25.37%。在渗透压耐受性状关联的位点周围发现了基因AT3G48750（CdcaAT），Cdc2aAT基因功能缺失会引起组蛋白H1激酶活性下降，引起细胞分裂速度降低，细胞变大，从而影响植物耐受性。