谷氨酸信号调控玉米幼苗耐热性的生理生化机制

Physiological and biochemical mechanism of glutamate signal on heat tolerance in maize seedlings

本研究通过对玉米幼苗外施不同浓度α-酮戊二酸(α-OG)及谷氨酸(Glu)预处理分别提高幼苗内源和外源Glu水平,研究Glu信号对热胁迫(46℃,16 h)下玉米幼苗生长发育及耐热性的影响。结果表明:与蒸馏水处理相比,不同浓度α-OG及Glu预处理显著提高幼苗在热胁迫下存活率,并以40 mmol·L^(-1)α-OG(α-OG-40)及1 mmol·L^(-1)Glu(Glu-1.0)效果最佳。α-OG-40及Glu-1.0预处理显著提高热胁迫前后的幼苗株高、根长、总叶绿素含量、组织活力,降低了丙二醛(MDA)水平,显著增强幼苗整体素质。α-OG-40及Glu-1.0预处理显著提高热胁迫前后幼苗中可溶性蛋白、可溶性糖、脯氨酸及甜菜碱含量,增强幼苗的渗透调节能力。α-OG-40及Glu-1.0预处理显著提高热胁迫前后幼苗中抗坏血酸过氧化物酶(APX)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GPX)、超氧化物歧化酶(SOD)及谷胱甘肽还原酶(GR)活性,加强活性氧清除能力,降低热胁迫对幼苗损伤。

By applying different concentrations ofα-Ketoglutaric acid(α-OG)and glutamate(Glu)to maize seedlings for increasing the endogenous and exogenous Glu level in plants respectively,we investigated the effects of Glu signal on the growth,development and heat tolerance of maize(Zea mays)seedlings under heat(46℃,16 h)stress in this study.The results showed that,compared with the control with distilled water,pretreatment with different concentrations ofα-OG and Glu significantly increased the survival rate of seedlings under heat stress,and 40 mmol·L^(-1)α-OG(α-OG-40)and 1.0 mmol·L^(-1)Glu(Glu-1.0)displayed the optimal effects among them.Treatments withα-OG-40 and Glu-1.0 significantly enhanced the plant height,root length,total chlorophyll content and tissue vigor,but decreased malonadehyde(MDA)content,then improved the seedlings quality before and after heat stress.Application ofα-OG-40 and Glu-1.0 remarkably increased the levels of proline,betaine,soluble sugar and protein,strengthened the osmotic adjustment of seedlings before and after heat stress.Theα-OG-40 and Glu-1.0 treatments greatly increased the activities of ascorbate peroxidase(APX),catalase(CAT),glutathione peroxidase(GPX),superoxide dismutase(SOD)and glutathione reductase(GR)of seedlings,which enhanced the scavenging ability of reactive oxygen species and reduced the damage of heat stress on seedlings.