水杨酸缓解穿心莲盐胁迫的机制研究

Mechanism of salicylic acid ameliorates salt-induced changes in Andrographis paniculata

该实验以穿心莲幼苗为实验材料,研究水杨酸(salicylic acid,SA)对盐(NaCl)胁迫下穿心莲的生长及有效成分积累的影响。研究结果表明:随着NaCl浓度的增加,穿心莲幼苗生长受到明显抑制,胡萝卜素和类胡萝卜素含量呈下降趋势;抗氧化酶活性增强;同时丙二醇、脯氨酸、可溶性蛋白含量呈上升趋势;穿心莲内酯、新穿心莲内酯、脱水穿心莲内酯含量呈上升趋势,而去氧穿心莲内酯呈下降趋势。以100 mmol·L-1 NaCl+5 mg·L-1 SA处理,穿心莲叶片中的抗氧化酶活性均有显著的上升趋势,用100 mmol·L-1 NaCl+10 mg·L-1 SA处理时穿心莲叶片中可溶性蛋白及脯氨酸含量均显著变化,同时穿心莲叶片中MDA含量显著降低。SA对盐胁迫下穿心莲幼苗的生长,以10 mg·L-1 SA的缓解效果最佳。在50 mmol·L-1 NaCl+10 mg·L-1 SA的处理下穿心莲幼苗的鲜重、干重及叶干重达到最高,分别是对照组的1.02,1.09,1.11倍。不同浓度的NaCl和10 mg·L-1 SA处理时4种内酯含量均显著高于对照组。选取了穿心莲二萜内酯合成途径上的4个关键酶基因,来探讨水杨酸缓解盐胁迫下穿心莲二萜内酯合成的分子机制。随着盐胁迫的加强,HMGR,GGPS,ApCPS的相对表达量均呈上调趋势,证明盐胁迫可能加强MVA途径合成穿心莲二萜内酯。SA可有效促进盐胁迫下穿心莲的生长发育,提高穿心莲渗透调节能力和抗氧化能力,提高穿心莲的耐盐性,缓解盐胁迫对穿心莲的影响。

In this study, Andrographis paniculata seedlings were used as experimental materials to study the effects of salicylic acid(SA) on the growth and effective component accumulation of A. paniculata under NaCl stress. The results showed that with the increase of NaCl concentration, the growth of A. paniculata seedlings was significantly inhibited, and the content of carotene and carotenoid decreased. The activity of antioxidant enzyme was enhanced. At the same time, the contents of proline, proline and soluble protein were on the rise. The contents of andrographolide, new andrographolide and deoxyandrographolide showed an upward trend, while deoxyandrographolide showed a downward trend. Treatment with 100 mmol·L-1 NaCl+5 mg·L-1 SA showed a significant increase in antioxidant enzyme activity in A. paniculata leaves. Treatment with 100 mmol·L-1 NaCl+10 mg·L-1 SA showed significant changes in soluble protein and proline content in A. paniculata leaves, while MDA content in A. paniculata leaves significantly decreased. 10 mg·L-1 SA had the best effect on the growth of A. paniculata seedlings under salt stress. Under the treatment of 50 mmol·L-1 NaCl+10 mg·L-1 SA, fresh weight, dry weight and leaf dry weight of A. paniculata seedlings reached the highest level, which were 1.02, 1.09 and 1.11 times of those in the control group, respectively. The concentrations of NaCl and 10 mg·L-1 SA were significantly higher than those of the control group. Four key enzyme genes of A. paniculata diterpene lactone synthesis pathway were selected to explore the molecular mechanism of salicylic acid to alleviate salt stress. With the increase of salt stress, the relative expressions of HMGR, GGPS and ApCPS were up-regulated, indicating that salt stress may enhance the synthesis of A. paniculata diterpene lactone through MVA pathway. SA can effectively promote the growth and development of A. paniculata under salt stress, improve its osmotic regulation and antioxidant capacity, improve its salt tolerance, and alleviate the effects of salt stress on A. paniculata.