硫化氢信号能够通过生物钟调控拟南芥对冷胁迫的响应

硫化氢(hydrogen sulfide, H_2S)是继一氧化氮(nitric oxide, NO)与一氧化碳(carbon oxide, CO)之后的第3种气体信号分子,在动植物中均发挥着重要的生理功能。生物钟是生物体的内在计时器,对动植物适应环境和生长发育至关重要。鉴于H_2S与生物钟调控的生理过程有较大的相关性,本文以拟南芥(Arabidopsis thaliana)为实验材料,对二者之间的关系进行了探索。结果发现,外源NaHS(H_2S供体)处理能够上调生物钟相关基因CCA1(circadian clock associated 1)和PRR9(pseudo-response regulator 9)的表达,而且在H_2S生成关键酶编码基因缺失的双突变体lcd/des1中,CCA1与PRR9的峰值表达时间明显滞后。CBFs(c-repeat binding factors)是受CCA1调控的冷胁迫响应基因,其表达也受H_2S的调控。lcd/des1中CBF1和CBF3的峰值表达时间延迟,同时在lcd/des1中CBF1、CBF2和CBF3都下调表达。lcd/des1幼苗对冷胁迫表现出更高的敏感性。本文也对拟南芥内源H_2S生成关键酶L-半胱氨酸脱硫基酶(L-cysteine desulfhydrase, LCD)与脱硫基酶1(desulfhydrase 1, DES1)编码基因的转录水平节律性进行了初步的探索。LCD的表达在1 d内未见明显的变化,而DES1的表达有明显的节律性,在早上8:00达到峰值。综上所述,H_2S能够通过调节CCA1与PRR9基因的表达调控生物钟,进而影响下游靶标CBFs基因的表达以增加拟南芥对冷胁迫的耐受性。

Hydrogen Sulfide Signaling Alleviates the Cold Stress Through Circadian Clock in Arabidopsis thaliana

.Hydrogen sulfide (H2S), the third gasotransmitter after nitric oxide and carbon oxide, performs important functions in both animals and plants. Circadian clock is internal timekeeper of organisms, which is crucial for environment adaption, growth and development. The relationship between H2S and circadian clock in Arabidopsis thaliana was explored because they have many overlap functions. The results showed that NaHS (H2S donor) could up-regulated the gene expression levels of CCA1 (circadian clock associated 1) and PRR9 (pseudo-response regulator 9) which are core circadian clock genes. The peak expression levels of CCA1 and PRR9 were delayed in H2S synthesis mutant lcd/des1. The expression of CBFs (c-repeat binding factors), the cold stress response genes that are the downstream target of CCA1, was also regulated by H2S. In lcd/des1, the peak expression of CBF1 and CBF3 was delayed and the expression levels of CBF1, CBF2 and CBF3 were decreased. The seedlings of lcd/des1 were more sensitivity to cold stress than WT. The diurnal change of LCD (L-cysteine desulfhydrase) and DES1 (desulfhydrase 1), which encode H2S production enzymes in Arabidopsis, was also analyzed. The expression of LCD did not change significantly during 1 d, however, the expression of DES1 showed diurnal change with peak at 8 in the morning. In summary, H2S can regulate the expression levels of clock genes CCA1 and PRR9, as well as its downstream genes CBFs to increase resistance to cold stress in Arabidopsis thaliana.