水杨酸调控内源H_2S缓解黑大豆铝胁迫的作用机理研究

Mechanism of Salicylic Acid Regulating Endogenous H_2S Alleviating Aluminum Stress in the Root of Black Soybean

该研究以铝(Al)敏感型黑大豆(SB)根为实验材料,通过一系列生理生化和组织化学实验手段,探讨了水杨酸(SA)通过调控内源H_2S信号缓解铝胁迫的作用方式。结果表明:(1)AlCl_3处理黑大豆SB根系Al积累增加,AlCl_3与SA共处理能明显抑制Al在SB根系的累积,加入H_2S清除剂(HT)或H_2S合成抑制剂(PAG)后SB根系Al累积量增加。(2)SA使Al胁迫下黑大豆(SB)根内源H_2S水平增加1.5倍,并显著缓解Al胁迫导致的根生长抑制、活性氧(ROS)累积、氧化损伤和细胞死亡,共处理HT或PAG均能够显著降低内源H_2S水平,并可逆转上述所有SA对Al胁迫的缓解效应。(3)SA降低了Al胁迫下黑大豆(SB)根尖抗氧化酶CAT、SOD和APX活性,抑制SB根系细胞ROS的产生,用HT或PAG抑制H_2S信号可增强抗氧化酶活性。(4)在Al胁迫条件下,SA可进一步上调一系列耐Al基因的表达,包括外部解毒机制中的耐铝转录因子GmART1、柠檬酸合成酶基因GmCS、柠檬酸转运蛋白基因GmMATE,内部解毒机制中的苹果酸转运蛋白基因GmAlCT以及Al3+相关转运蛋白基因GmAlS1和GmNIP1;2,通过HT或PAG降低内源H_2S水平可逆转SA对上述基因表达的调控。(5)SA可提高Al胁迫下黑大豆(SB)根柠檬酸的分泌量,此效应亦可被HT或PAG抑制。研究发现,H_2S可作为SA的下游信号参与调控黑大豆(SB)响应Al胁迫的过程,为揭示植物Al耐受信号调控网络途径提供部分新的理论基础。

In this study,physiological-biochemical and histochemical approaches were applied to investigate the role of H2S in salicylic acid(SA)-alleviated Al stress in the root of SB(aluminum(Al)-sensitive black soybean).The results showed that:(1)Al accumulation in black soybean(SB)roots was increased by AlCl3 treatment and the co-treatment of AlCl3 and SA could significantly inhibit the accumulation of Al.But after adding H2S scavenger(HT)or H2S synthesis inhibitor(PAG),the accumulation of Al in SB roots was aggravated.(2)SA increased endogenous H2S levels of black soybean(SB)root by 1.5-fold under Al stress,and significantly alleviated root growth inhibition,reactive oxygen species(ROS)accumulation,oxidative damage and cell death induced by Al stress.Co-treatment of HT or PAG significantly reduced endogenous H2S level,and it can reverse the alleviation effect of all SA under Al stress.(3)SA reduced the activities of black soybean(SB)apical antioxidant enzyme CAT,SOD and APX under Al stress,and inhibited the production of ROS in SB root cells.Inhibition of H2S signal by HT or PAG enhances antioxidant enzyme activities.(4)Under the condition of Al stress,SA can further up-regulate the expression of a series of Al tolerance-related genes,such as exclusion mechanism-related genes(Al-responsive transcription factor,GmART1;citric acid synthase,GmCS;citric acid transporter,GmMATE)as well as internal Al tolerance mechanism-related genes(malic acid transporter,GmAlMT;Al3 +-related transporters,GmAlS1 and GmNIP1;2).Reduction of endogenous H2S level by HT or PAG can reverse the regulation of SA expression on these genes.(5)SA can increase the secretion of citric acid from black soybean(SB)root under Al stress,and this effect can also be inhibited by addition of HT or PAG.The study found that H2S acted as a downstream signaling of SA and participate in the regulation of black soybean(SB)response to Al stress,which might provide some novel scientific basis for understanding Al-tolerance signaling network in plants.