沉水植物川蔓藻生长的耐盐特性及其机制研究

Study on salinity tolerance and its mechanism of submerged plant Ruppia maritima

目前在入海河流等含盐水体的生态修复研究中有关耐盐沉水植物的研究还较为缺乏.本研究以从野外筛选获得的一株耐盐性能优良的沉水植物川蔓藻为对象,对其耐盐特性及机制,以及应用于河道氮、磷去除的潜力等进行了研究.结果表明,沉水植物川蔓藻具有良好的耐盐性能,在盐度为0~25‰的环境中均保持了较高的生长速率.当盐度上升至30‰时,筛选的川蔓藻植株的生长虽然受到了一些影响,但仍然保持了0.047 d^(-1)的比生长速率.盐度对川蔓藻的氮、磷去除存在一定影响,随着盐度上升,氮、磷去除率基本呈逐渐下降趋势.另外,通过转录组分析方法进一步分析了川蔓藻植株耐受高盐环境的机制.结果表明,在外界盐度胁迫影响下,川蔓藻植株下调表达基因的数量明显多于上调表达基因.差异表达基因的GO富集分析表明,盐度胁迫下川蔓藻差异表达基因显著富集的GO term主要集中于生物学过程和分子功能.差异表达基因的KEGG富集分析表明,盐度胁迫显著改变了川蔓藻光合作用和物质代谢相关通路的基因的表达.另外,本研究还分析了编码多种抗氧化酶系统中重要酶的基因的表达情况,结果表明,川蔓藻抗坏血酸过氧化物酶、超氧化物歧化酶、过氧化氢酶、植物过氧化物酶等相关基因的表达量受到盐度的明显影响,盐度促进了其中大部分基因的上调表达,表明酶促抗氧化系统在川蔓藻的耐盐过程中发挥了重要作用.

At present,there are few studies on salt-tolerant submerged plants used in the ecological remediation of saline water bodies such as coastal rivers.In this study,a submerged plant(Ruppia maritima)with excellent salt tolerance was obtained from the field,and its salinity tolerance characteristics and mechanism,as well as its potential application in nitrogen and phosphorus removal,were studied.The results showed that Ruppia maritima had good salinity tolerance and maintained a high growth rate in the water with salinity of 0~25‰.When the salinity increased to 30‰,although the growth of Ruppia maritima was inhibited to a certain extent,it still maintained a specific growth rate of 0.047 d^(-1).The salinity had a certain effect on the removal of nitrogen and phosphorus.With the increase of salinity,the removal rate of nitrogen and phosphorus decreased gradually.In addition,the mechanism of Ruppia maritima tolerance to high salt was further analyzed by transcriptome analysis.The results showed that the number of down-regulated genes was significantly more than up-regulated genes under salinity stress.The GO enrichment analysis of differentially expressed genes(DEGs)showed that the GO term with significant enrichment of DEGs in Ruppia maritima under salinity stress mainly focused on biological processes and molecular functions.KEGG enrichment analysis of DEGs showed that salinity stress significantly altered the expression of genes related to photosynthesis and substance metabolism in Ruppia maritima.In addition,transcriptome sequencing was used to analyze the expression of genes encoding important enzymes in various antioxidant enzyme systems.The results showed that the expression levels of related genes such as ascorbate peroxidase,superoxide dismutase,catalase,and plant peroxidase were significantly affected by salinity.Salinity promoted the up-regulated expression of most of the genes related to antioxidant enzymes,suggesting that the enzyme-induced antioxidant system played an important role in the process of salt tolerance.