中文摘要：

硫化氢（H2S）是调节植物生长发育和响应胁迫的重要气体信号分子,为了增加对白菜（Brassica rapavar.pekinensis）应答冷胁迫生理机制的理解,该研究分析了4℃冷胁迫条件下外源H2S（5μmol·L^-1硫氢化钠水溶液熏蒸24h）预处理对白菜幼苗生长、光合作用以及相关基因表达水平的影响。结果发现：（1）冷胁迫诱导后白菜内源H2S主要生成酶编码基因LCD、DCD、DES的表达水平极显著上调,并伴随H2S产率的显著增加,暗示二者之间存在着潜在紧密联系。（2）在冷胁迫条件下,外源H2S预处理的白菜幼苗地上部分高度、叶宽和相对含水量等指标均比对照表现出明显优势;其体内脯氨酸、可溶性糖以及光合色素含量大幅升高,光合速率显著提升,光合作用中部分捕光蛋白、铁氧还蛋白和硫氧还蛋白编码基因表达量同时显著上调。研究表明,生理浓度H2S预处理可通过诱导上调白菜幼苗光合作用的相关基因表达量和提升净光合速率,提高其光合作用强度,促进渗透调节物质积累,有效缓解冷胁迫对其造成的损伤,维持冷胁迫下白菜幼苗的生长。

英文摘要：

Hydrogen sulfide（H2S）has been known as a new gasotransmitter which plays a vital role in regulating plant growth and responding to stresses.For deepening the understanding of physiological mechanism on the response to chilling stress in Chinese Cabbage（Brassica rapavar.pekinensis）,we analyzed the influence of the seedlings growth conditions,photosynthesis and related genes expression levels under chilling stress which pretreated with exogenous H2S（5μmol·L^-1 NaHS treated 24h）.The results showed that：（1）The chilling stress activated the endogenous production of H2S,and up-regulated the expression of the cysteine desulfhydrases coding genes,LCD,DCDand DES,which were identified as the main genes for endogenous H2S emission.These data implied the close correlation among them.（2）The cabbage seedlings pretreated with H2S showed obvious advantages in the aerial part height,the leaf width and the relative water content under chilling stress.The proline,the soluble sugar content and the photosynthetic pigment were increased significantly,along with the great improvement of the photosynthetic rate.And,the coding genes of some light-harvesting protein,ferredoxin,thioredoxin were up-regulated dramatically after pretreated with H2S.From all these results,it could be concluded that physiological concentrations of H2S could raise the photosynthesis through up-regulating the photosynthesis related-genes and Pn,promote osmotic adjustment and relieve the damage caused by chilling that could maintain the growth of cabbages under chilling stress.