渍涝胁迫下玉米体内多胺变化及其分子调控机制

Polyamines play an important role in the regulation of senescence and stress-resistance of plants. In our experment results showed that exogenous polyamines could alleviated the harm to maize roots and leaves by waterlogging. But little is known about the effect of waterlogging stress on PAs content, metabolism and molecular mechanisms of maize. In the present study, Four maize cultivar seedlings with differentwaterloging-resistances were used to study the relationship between PA changes and waterlogging -resistance. Free polyamines content in the seedling roots and non-covalent bound polyamines on plasma membrane, mitochondrial membrane and ribosome will be tested by HPLC. Activity of polyamines biosynthesis and oxidase will be invested by spectrophotometry and gene expression of polyamines biosynthesis and oxidase will be quantified by RT-PCR. The aim of this study was to explore: ①polyamines components and free polyamines contents in maize seedlings under waterlogging; ②the content and function of the bound polyamines in the membrane protein; ③the relationship between the activity and gene expression of polyamines biosynthesis and oxidase and the treatment of exogenous polyamines. The result of this project would do help to elucidate the contents variation and function of polyamines under waterlogging stress and the regulation mechanism at the molecular level; provide more knowledge of the stress resistance physiological of polyamines by elucidating the physiological and molecular regulation mechanisms of exogenous polyamines treatment. This would also provide a theoretical guide for improving crop waterlogging tolerance and maize yield by using exogenous polyamines.

多胺是植物体内重要的调节物质，在植物抵御逆境胁迫及信号转导中承担着重要角色，前期研究初步发现外源多胺能有效缓解玉米的渍涝胁迫伤害，但渍涝胁迫下玉米体内多胺的变化规律及其响应胁迫的生理和分子机制尚不清楚。本研究以耐涝性不同的玉米幼苗为材料，利用HPLC技术和RT-PCR技术检测渍涝胁迫下玉米幼苗体内多胺组分、游离态多胺含量和主要膜蛋白上结合态多胺含量变化及其功能；明确渍涝胁迫下多胺合成酶和氧化酶活性变化及其基因差异表达。阐明多胺在玉米响应渍涝胁迫中的生理作用及分子机制，以丰富多胺信号转导和多胺抗性生理研究，为研发作物渍涝灾害缓解技术提供理论依据。

多胺是植物体内重要的调节物质，在植物抵御逆境胁迫及信号转导中承担着重要角色，研究多胺调控对渍涝胁迫下玉米体内多胺的变化规律及其响应胁迫的生理和分子机制对缓解玉米渍涝灾害具有重要研究意义。本研究以两类典型品种为研究材料，利用HPLC技术和RT-PCR技术等技术检测渍涝胁迫下玉米幼苗体内多胺组分、多胺含量变化及其功能；明确渍涝胁迫下多胺合成酶和氧化酶活性变化及其基因差异表达。结果表明：外施Spd增加了淹水胁迫下两个玉米品种的地上部干重、株高、相对干重增长速率(RDIR)和相对含水量(RWC)，降低了活性氧(ROS)和丙二醛(MDA)的积累；提高了叶片中超氧化物歧化酶(SOD)、过氧化物酶(POD)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)和过氧化氢酶(CAT)活性及还原型谷胱甘肽(GSH)和还原性抗坏血酸(AsA)含量，外施Spd亦使叶片中脯氨酸、可溶性糖、可溶性蛋白和游离氨基酸含量升高。外施Spd增强了淹水胁迫下玉米幼苗的抗氧能力和渗透调节能力，尤其以渍涝敏感的品种DH662的反应更为敏感。淹水后玉米叶片和根中游离态和结合态腐胺、精胺和亚精胺含量随着淹水天数的增加呈上升趋势。但不同品种升高的幅度不同;采用外源喷施多胺后，叶片和根中的腐胺含量显著下降，亚精胺和精胺含量明显提高，以敏感性品种变化幅度较大，结合态多胺变化趋势与游离态相似。淹水胁迫下叶片和根系中PAO活性增强，ODC酶活性降低，SAMDC酶活性下降。幼苗根系中ADC基因相对表达量与对照相比均上调，如XD20其基因相对表达量较CK分别上升了270.28%和189.94%，DH662分别升高了114.76%和191.73%。外施Spd后，ADC基因相对表达量较胁迫下均有不同程度的升高，外源Spd可通过上调ADC酶相关基因相对表达量和SAMDC相关基因相对表达量适应渍涝胁迫，但两个品种间差异显著，XD20中其相对表达量较CK先下降后上升，DH662则均高于CK；外施Spd后，其与氧化和合成酶相关的基因相对表达量在两个品种的调控效应存在差异显著。