外源NO供体对水分亏缺下玉米叶片碳同化关键酶及抗氧化系统的影响

为了探讨外源NO供体(硝普钠, SNP)对水分亏缺下玉米叶片碳同化关键酶及抗氧化系统的影响及其调控机制, 在20% PEG-6000模拟水分亏缺胁迫下, 研究了SNP对玉米品种驻玉309幼苗叶片光合碳同化核酮糖-1,5-二磷酸羧化/加氧酶(Rubisco)和Rubisco活化酶(RCA)活性及其基因表达、抗氧化酶活性及其同工酶谱变化的影响。结果表明, 在水分亏缺胁迫下, SNP显著上调玉米叶片rbc L、rbc S、rca β基因的相对表达量, 尤其是叶片rbc S基因的相对表达量增加1.86倍, 叶片Rubisco、RCA活性分别提高32.7%和14.67%; 叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性及其同工酶谱带的宽度和亮度显著增强, 而ROS积累量明显降低。说明在PEG水分亏缺胁迫下, SNP能显著提升玉米幼苗叶片光合碳同化能力及抗氧化酶活性, 降低ROS积累及其对细胞膜造成的损伤, 提高玉米的抗干旱性。

Effect of Exogenous Nitric Oxide Donor on Carbon Assimilation and Antioxidant System in Leaves of Maize Seedlings under PEG-induced Water Deficit Stress

The objective of this study was to explore the effect of exogenous nitric oxide (NO) donor (sodium nitroprusside, SNP) on key enzymes of carbon assimilation and antioxidant system of maize leaves under water deficit and its regulation mechanism. In this experiment, 20% PEG-6000 was used to stimulate water deficit stress, exogenous SNP was added into root rhizosphere of seedlings in maize variety Zhuyu 309. After three days of stresses, the changes of Rubisco and RCA activities and their gene level, antioxidase activity and their isoenzyme spectrum level were investigated. The expression levels of rbc L, rbc S, rca β were increased significantly, especially for rbc S that was increased the most by 1.86 fold, which resulted in up-regulation of Rubisco and RCA activities by 32.7% and 14.67% under exogenous SNP plus PEG stress. In addition, SNP enhanced the activity of SOD, POD, CAT, and the width in their isoenzyme spectrum, resulting in significant reduction of ROS accumulation. These results suggested that NO could increase photosynthetic carbon assimilation capacity and antioxidase activity, alleviate the damage of ROS burst on the cell membrane, which enhances PEG-simulated water deficit resistance of maize seedlings.