外源褪黑素对干旱胁迫下不同抗旱型玉米幼苗生理特性的影响

Effects of exogenous melatonin on physiological characteristics of different drought-resistant maize seedlings under drought stress

【目的】为研究外源褪黑素对玉米幼苗抗旱性的影响。【方法】以‘东单507’、‘京科665’、‘郑单958’等9份不同抗旱型玉米为试验材料,进行干旱胁迫试验。测定玉米幼苗表型指标、抗氧化酶活性和渗透调节物质含量等指标,从形态和生理水平阐明干旱胁迫下不同抗旱型玉米对外源褪黑素的响应。【结果】对干旱胁迫下不同抗旱型玉米施加外源褪黑素后,玉米幼苗的株高、叶面积、地上部生物量、叶绿素含量以及叶片相对含水量显著增加;丙二醛含量显著降低;脯氨酸含量、可溶性糖含量、可溶性蛋白含量、超氧化物歧化酶活性、过氧化物酶活性、抗坏血酸过氧化物酶活性均显著升高。【结论】外源褪黑素通过提高玉米的抗氧化能力,增强干旱胁迫下不同抗旱型玉米的干旱适应性,使玉米抗旱性提高。相比于干旱敏感型玉米,对抗旱型玉米效果更显著。

[Objective]To study the effect of exogenous melatonin on drought tolerance of maize seedlings and to investigate the mechanism of melatonin-induced drought tolerance.[Methods]Nine different drought-resistant maize types,including Dongdan 507,Jingke 665 and Zhengdan 958,were used as test materials for the drought stress test.The biomass,antioxidant enzyme activity and osmoregulatory substance content of maize seedlings were measured to elucidate the response of different drought-resistant maize types to exogenous melatonin under drought stress at the morphological and physiological levels.[Results]The results showed that the application of exogenous melatonin to different drought-resistant maize types under drought stress significantly increased the plant height,leaf area,above-ground biomass,chlorophyll content and leaf relative water content of maize seedlings;significantly decreased the MDA content;and significantly decreased the proline content,soluble sugar content,soluble protein content,superoxide dismutase(SOD)activity and peroxidase(POD)activity,Ascorbate peroxidase(APX)activity were significantly increased.[Conclusion]Exogenous melatonin enhanced the drought adaptability of different drought-resistant maize types under drought stress by increasing the antioxidant capacity of maize,resulting in an increase in drought resistance of maize.Compared with drought-sensitive maize,the effect on drought-resistant maize was more significant.