芝麻不同抗旱基因型对花期干旱胁迫的生理响应机理

Physiological Response Mechanism of Drought Stress in Different Drought-Tolerance Genotypes of Sesame During Flowering Period

【目的】研究干旱胁迫对不同抗旱性芝麻品种叶片和根系生理生化特性的影响,分析不同基因型芝麻对花期干旱胁迫的生理响应差异,为芝麻抗旱性研究和改良提供理论参考。【方法】采用盆栽法,以抗旱品种金黄麻和干旱敏感品种竹山白为试验材料,在花期进行轻度(T1)、中度(T2)和重度(T3)干旱胁迫处理,以正常浇水为对照(CK),分别测定植株叶片和根系的丙二醛(MDA)、过氧化氢(H_2O_2)、脯氨酸(Pro)、可溶性糖(SS)、可溶性蛋白(SP)、游离氨基酸(AA)、还原型谷胱甘肽(GSH)、还原型抗坏血酸(AsA)等含量,超氧化歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和苯丙氨酸解氨酶(PAL)活性,分析干旱胁迫下2个基因型间生理响应机理的差异。【结果】干旱胁迫后,芝麻叶片中MDA、H_2O_2、Pro、SS、SP、GSH含量和SOD、POD、PAL酶活性以及根系中MDA、SS、SP、AA、GSH、AsA含量和CAT、PAL活性随着胁迫程度的不断加剧呈不断上升趋势,叶片中的AA、AsA含量和CAT活性以及根系中H_2O_2、Pro含量和SOD、POD活性随着胁迫程度的加剧呈先升后降趋势。相关分析结果显示,叶片中各项指标测定值与根系中指标值均呈正相关,品种抗旱性与膜脂过氧化伤害物质(MDA和H_2O_2)含量呈负相关,与部分渗透调节物质、防御系统物质含量和保护酶活性呈正相关。【结论】在花期干旱胁迫下,对2个不同基因型芝麻测定的12个生理生化指标均出现不同程度上升,响应差异较大,叶片大于根系。抗旱品种较干旱敏感品种表现为细胞膜脂过氧化伤害较轻,渗透调节物质积累量较多,保护酶(SOD和CAT)活性较强,抗氧化物质(GSH和AsA)含量较高。芝麻抗旱性生理机理表现为多方面的综合防御。

【Objective】The aims of this study were to study the effects of drought stress on the physiological and biochemical characteristics of leaves and roots of different drought-tolerant sesame varieties, to analyze the physiological responses of sesame different genotypes under drought stress during flowering period, thus providing a theoretical reference for the studies of sesame drought-tolerant and its improvement. 【Method】This experiment adopted the method of potted to drought-tolerant varieties'Jinhuangma' and drought-sensitive varieties 'Zhushanbai' as the experimental materials, and treatment with mild(T1), moderate(T2) and severe(T3) drought stress at the flowering period, with normal irrigation as the control(CK). The contents of malondialdehyde(MDA), H2O2, proline(Pro), soluble sugar(SS), soluble protein(SP), free amino acids(AA), reduced ascobate(AsA), and reduced glutathione(GSH), as well as activities of superoxide dismutase(SOD), peroxidase(POD), catalase(CAT),phenylalanine ammonialyase(PAL) in plant leaves and roots were determined, respectively. And then the differences of physiological response mechanism between two genotypes under drought stress were analyzed. 【Result】 After drought stress, the contents of MDA, H2O2, Pro, SS, SP, and GSH with the activities of SOD, POD and PAL in sesame leaves, as well as contents of MDA, SS, SP,AA, GSH, AsA and CAT and PAL activity in roots showed an increasing trend with the aggravation of stress degree, and AA, AsA content and CAT activity in leaves and contents of H2O2, Pro and SOD, POD activity in roots showed a trend of first rising and then falling with the aggravation of stress degree. The results of correlation analysis showed that the measured value of physiological and biochemical indexes in leaves were all positively correlated with them in roots, and the drought-tolerance of varieties was negatively correlated with the content of membrane lipid peroxidation damage substances(MDA and H2O2), and positively correlated with partial osmotic regulatory substances, defense system substances and protective enzyme activities. 【Conclusion】Under drought stress during the flowering period of sesame, 12 physiological and biochemical indexes of two different genotypes of sesame all showed different degree of increase, with great difference in response, and the effect on the leaves was greater than that of the roots.Drought-tolerant varieties showed less cell membrane lipid peroxidation damage, more accumulation of osmotic regulatory substances, stronger activity of protective enzymes(SOD and CAT) and higher content of antioxidant substances(GSH and AsA)than that in drought-sensitive varieties. Drought-tolerance of sesame showed comprehensive defense in many factors on physiological and biochemical indexes.