油莎豆耐盐性评估及盐胁迫下幼苗根系转录组学分析

Evaluation of salt tolerance in Cyperus esculentus and transcriptomic analysis of seedling roots under salt stress

油莎豆是一种综合利用价值高的新型经济作物,抗逆性极强,具有在盐渍化土壤上种植发展的潜力。为明确其耐盐特性,本研究设置5个NaCl浓度(0、0.3%、0.6%、0.9%和1.2%),分析了NaCl胁迫对油莎豆茎豆萌发和幼苗生长过程中形态和生理指标的影响。结果表明,在0.3%和0.6%NaCl胁迫下,茎豆发芽率、幼苗根长和苗高受影响程度较小;根系中膜受损程度指标物丙二醛(MDA)和氧化胁迫物过氧化氢(H2O2)的含量增加不显著,而渗透调节物甜菜碱(GB)、脯氨酸(Pro)的含量和抗氧化酶超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)的活性显著提高,整体上受到的盐胁迫伤害较小。而在0.9%和1.2%NaCl胁迫下,盐胁迫伤害十分明显,茎豆萌发和幼苗生长受到严重的抑制。为进一步鉴定油莎豆耐盐相关基因,利用RNA-seq技术检测了0、0.3%和0.6%NaCl胁迫下油莎豆根系的基因表达情况。通过基因差异表达分析、加权基因共表达网络分析(WGCNA)以及GO富集分析发现,24个主要与氧化还原、跨膜转运、几丁质水解相关的GOterms显著富集,涉及了15个显著上调表达基因。其中,DN23985_c0_g1、DN2960_c0_g1、DN8384_c1_g1分别编码玉米黄质环氧酶、L-抗坏血酸过氧化物酶、谷胱甘肽转移酶,具有抗氧化作用,参与抗氧化调节;DN21785_c1_g1和DN6596_c0_g1二者均编码氨基酸转运蛋白,可能通过积累氨基酸类小分子(如Pro)而增强渗透调节;DN14393_c0_g1编码几丁质酶,能够水解几丁质而促进植物应对胁迫响应。本研究明确了油莎豆在0.6%及以下浓度NaCl胁迫时具有较好的耐盐性,并进一步筛选出耐盐相关基因,为油莎豆在盐渍化土壤的种植和耐盐品种的培育提供了重要的参考。

Cyperus esculentus is a new industrial crop with the high comprehensive utilization value,which is a strongly resistant to stresses and has a great potential to grow in saline soil.In order to clarify its salt tolerance,five NaCl concentrations(0,0.3%,0.6%,0.9%,and 1.2%)were set in this study to analyze the effects of NaCl stress on morphological and physiological indexes during germination and seedling growth.The results showed that the germination percentage,root length,and seedling height were less affected under 0.3%and 0.6%NaCl stresses.Meanwhile,the contents of indicator of membrane damage degree,malondialdehyde(MDA),and oxidative stress substance,hydrogen peroxide(H2O2),did not increase significantly.However,the contents of osmoregulation substances[glycine betaine(GB),and proline(Pro)]and the activities of antioxidant enzymes[superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)]were significantly increased,and the damage of salt stress was less on the whole.However,under 0.9%and 1.2%NaCl stresses,the salt stress injury was very obvious and the germination and seedling growth of Cyperus esculentus were severely inhibited.In order to further identify the genes related to salt tolerance,RNA-seq technology was used to detect the gene expression in roots under 0,0.3%,and 0.6%NaCl stresses.24 GO terms mainly related to oxidoreduction,transmembrane transport,chitin hydrolysis was significantly enriched,among which 15 significantly up-regulated genes were involved,through gene differential expression analysis,weighted gene co-expression network analysis(WGCNA),and GO enrichment analysis.Among them,DN23985_c0_g1,DN2960_c0_g1,and DN8384_c1_g1 encoded zeaxanthin epoxidase,L-ascorbate peroxidase,and glutathione S-transferase,respectively,which had antioxidant effects and participated in antioxidant regulation.Both DN21785_c1_g1 and DN6596_c0_g1 encoded amino acid transporters,which may enhance osmoregulation by accumulating small amino acid molecules such as Pro.DN14393_c0_g1 encoded chitinase,which hydrolyzed chitin and promoted plant response to stress.In this study,it was confirmed that Cyperus esculentus had a good salt tolerance under 0.6%or less NaCl stress,and the salt-tolerance related genes were further screened out,which provided an important reference for the cultivation in saline soil and the breeding of salt-tolerant varieties.