Abstract: To understand the effect of NO on proline accumulation induced by salt stress,the activities of both Δ¹-pyrroline-5-carboxylate synthetase(P5CS) and proline dehydrogenase(proDH) in ryegrass(Lolium perenne L.) seedlings under 150 mmol·L^-1 NaCl stress were investigated.Results show that both proline and NO contents in leaves and root tips of ryegrass seedling were increased under NaCl stress.The P5CS activities of ryegrass leaves and root tips were increased,while ProDH activities decreased in response to NaCl stress.Application of NO donor SNP(sodium nitroprusside)(100 μmol·L^-1) increased both proline contents and P5CS activities,and decreased ProDH activities in leaves and root tips of ryegrass seedling under NaCl stress.However,such effects of SNP and NaCl stress were reversed by the addition of either NO scavenger cPTIO or NO production inhibitors(either L-NAME or NaN₃).This study indicates that NO is involved in regulation of proline accumulation by mediating P5CS and ProDH activities under salt stress.

Key words: Nitric oxide, Proline, Salt stress, Ryegrass(Lolium perenne L.)

摘要： 以黑麦草(Loliumperenne L.)幼苗为材料,采用溶液培养方法研究了150 mmol·L^-1 NaCl胁迫下根尖和叶片中一氧化氮(NO)产生和脯氨酸(Pro)积累的关系,以探讨NO在盐胁迫下诱导Pro积累中的调节作用。结果表明:NaCl胁迫下黑麦草幼苗根尖和叶片中Pro和NO含量增加,Pro合成的关键酶吡咯啉-5-羧酸合成酶(P5CS)活性提高,而Pro降解的关键酶脯氨酸脱氢酶(ProDH)活性下降。100μmol·L^-1外源NO供体硝普钠(SNP)促进了NaCl胁迫下幼苗根尖和叶片中Pro的积累及P5CS活性的提高,降低了ProDH活性;NO清除剂cPTIO和合成抑制剂L-NAME,NaN₃逆转了NaCl胁迫和SNP对Pro积累的诱导作用及P5CS,ProDH活性的调节作用。因此,NO可能通过P5CS和ProDH活性参与盐胁迫下Pro积累的调控。

关键词: 一氧化氮, 脯氨酸, 盐胁迫, 黑麦草