南方型紫花苜蓿叶片响应盐胁迫的代谢组学分析

Metabolomics Analysis of Leaf Response of Southern Alfalfa under Salt Stress

为明确紫花苜蓿叶片对盐胁迫的响应机制,采用比较代谢组学方法与气相色谱和飞行时间质谱联用(GC-TOF/MS)技术分析了盐胁迫下野生型与突变体紫花苜蓿叶片的代谢产物差异。结果表明,盐胁迫对野生型和突变体紫花苜蓿的株高、根长、地上和地下部干质量的生长均有抑制作用,与CK(正常培养)相比,盐胁迫下突变体紫花苜蓿地上和地下部干质量、株高、根长的降幅小于野生型。通过主成分分析(PCA)与正交偏最小二乘法判别分析(OPLS-DA)方法,筛选出野生型与突变体紫花苜蓿叶片中有41种共同表达的差异代谢产物。与CK相比,盐胁迫下野生型紫花苜蓿叶片中甘露糖和葡萄糖等可溶性糖和脂肪酸代谢产物含量下降,参与TCA循环的柠檬酸、富马酸、α-酮戊二酸和琥珀酸等含量显著增加,而盐胁迫下突变体叶片中脯氨酸、谷氨酸、肌醇和甘露糖等有机化合物含量上升。推测,野生型紫花苜蓿的耐盐机制可能是促进TCA循环产生更多的ATP,而突变体紫花苜蓿的耐盐机制则可能是积累了较多的渗透物质(糖、肌醇、脯氨酸)。

In order to clear and definite the reaction mechanism of alfalfa leaves under salt stress,the difference in metabolites between wild and mutant alfalfa leaves under salt stress was analyzed by using comparative metabolomics,and GC/TOF-MS.The results showed that salt stress inhibited the growth of plant height,root length,above-ground and below-ground dry weight of wild-type and mutant alfalfa.Compared with the control(normal culture),the plant height,root length,above-ground and below-ground dry weight of mutant alfalfa under salt stress decreased less than that of wild type.Besides,41 co-expressed differential metabolites in both wild and mutant alfalfa leaves were screened out by using PCA and OPLS-DA.Compared with the control,the content of soluble sugar such as mannose and glucose and fatty acid metabolites decreased significantly under salt stress while the content of citric acid,fumaric acid,α-ketoglutaric acid and succinic acid involved in the TCA cycle increased significantly in the wild type alfalfa leaves.The content of organic compounds such as proline,glutamic acid,inositol and mannose increased in the leaves of mutants under salt stress.It indicated that the salt-tolerance mechanism of wild alfalfa might be producing more ATP by promoting the TCA cycle,while the salt-tolerance mechanism of mutant alfalfa might be accumulating more osmotic substances(such as sugar,inositol,proline).