基于盐胁迫的苦豆子种子生理特性和赖氨酸脱羧酶基因表达分析

Analysis of Physiological Characteristics and Lysine Decarboxylase Gene Expression of Sophora alopecuroides Under Salt Stress

【目的】本文研究了盐胁迫下苦豆子萌发种子的生理特性和赖氨酸脱羧酶基因SaLDC表达量的变化。【方法】用NaCl溶液胁迫苦豆子种子,统计盐胁迫后种子的各项活力指标,测定子叶的PMP、MDA和Pro含量以及SOD、POD、CAT抗氧化酶活性。qPCR测定SaLDC表达量,HPLC测定Cad含量。【结果】随着NaCl溶液浓度的增加,种子的各项活力指标降低,相对盐害率上升。苦豆子能耐受NaCl溶液胁迫,保持种子正常萌发率达到50%的阈值为200 mmol·L-1。轻度盐胁迫(NaCl溶液≤100 mmol·L-1)时,POD酶起主要保护作用,在重度盐胁迫(NaCl溶液>200 mmol·L-1)下,CAT酶起主要保护作用;SaLDC在子叶中表达量最高,下胚轴中表达量最低,盐胁迫促使该基因表达上调;子叶中未检测到Cad,但在下胚轴和胚根中随NaCl溶液浓度的增加Cad含量降低。【结论】盐胁迫影响苦豆子种子的萌发和相关耐盐生理特性,SaLDC对盐胁迫的应答存在组织特异性。

【Objective】The physiological characteristics of seeds germination of Sophora alopecuroides under salt stress and the expression of lysine decarboxylase gene SaLDC were observed in this paper.【Method】The seeds of S.alopecuroides were treated with NaCl solution before their vigor indexes of seeds under salt stress were calculated. The plasma membrane permeability(PMP), contents of MDA, Pro and the activities of SOD, POD and CAT were also measured. The expression of SaLDC was determined by qRT-PCR and the content of cadaverine were measured by HPLC. 【Result】With the increase of the concentration of NaCl solution, the vigor index of the seeds decreased, where as the relative salt damage rate increased. S. alopecuroides was proved to be a salt tolerant plant with a threshold for seed germination under NaCl stress was 200 mmol ·L-1 .Under mild salt stress(NaCl≤100 mmol·L-1), POD enzyme played a major protective role;But under severe salt stress(NaCl > 200 mmol · L-1), CAT enzyme played a major protective role. The expression of SaLDC was the highest in cotyledons and the lowest in hypocotyls. Salt stress caused the gene expression to be up-regulated in all measured organs. No Cad was detected in cotyledons, but the content of Cad decreased in hypocotyls and radicles with the increase of NaCl concentration.【Conclusion】Salt stress affected the germination and physiological characteristics of S. alopecuroides seeds. Tissue-specific expression of SaLDC was observed under salt stress.