| 摘要: |
| 【目的】系统研究高温胁迫对水稻苗期叶片生理特性的影响及其与水稻品种耐热性的关系，为制定耐热水稻品种的育种策略提供科学依据。【方法】以8个籼稻品种和8个粳稻品种为材料，在苗期设置对照（白天（07:00-19:00）28 ℃，夜晚（19:00-07:00）22 ℃,CK）和高温胁迫（白天（07:00-19:00）42 ℃，夜晚（19:00-07:00）35 ℃,HS）2种处理方式，根据幼苗存活率将供试品种分为高抗、中抗、敏感和高度敏感4个耐热性等级，研究高温胁迫对不同耐热性水稻品种苗期叶片的相对含水量、叶绿素含量、活性氧(ROS)积累、质膜损伤、抗氧化酶活性、渗透调节物质和内源激素含量的影响。【结果】高温胁迫下，东稻4号、湘两优2号、黄华占和长白9号的幼苗存活率较高，是苗期耐热性高抗品种；湘两优900、泰优390、郑旱6号、武运粳21、粤王丝苗和吉粳515是苗期耐热性高度敏感品种。与CK相比，HS处理导致苗期水稻叶片的相对含水量、叶绿素含量及内源IAA、Z+ZR和GA3含量下降，ROS积累、质膜损伤（MDA含量和相对电导率）、抗氧化酶（SOD、POD、CAT和APX）活性、渗透调节物质（脯氨酸和可溶性糖）含量和内源ABA含量升高。高温胁迫下，耐热性水稻品种苗期叶片的相对含水量，叶绿素含量，SOD、POD和CAT活性及内源ABA含量均显著高于热敏感品种，ROS含量、相对电导率和MDA含量显著低于热敏感品种，APX活性、渗透调节物质含量及内源IAA、Z+ZR和GA3含量无显著差异。高温胁迫下，水稻苗期叶片ROS积累量、抗氧化酶活性、质膜损伤程度和内源ABA含量与水稻苗期的存活率极显著相关，可作为耐热水稻品种筛选的参考评价指标。【结论】高温胁迫诱导水稻叶片ROS过量积累，引发氧化胁迫是导致叶片枯萎的重要原因，提高抗氧化防御能力和内源ABA信号通路是水稻抵抗高温胁迫的重要途径，可作为耐高温水稻种质资源的重要育种策略。 |
| 关键词: 水稻 高温胁迫 逆境生理 叶片生理特性 |
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| 基金项目:江西省自然科学基金项目（20202BABL213046）；江西省教育厅科学技术研究项目（GJJ190868） |
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| Response of leaf physiological characteristics of different rice -varieties to heat stress at seedling stage |
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JI Ping,LIU Jingwei,WANG Xinting,et al
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| Abstract: |
| 【Objective】The present study investigated the effects of heat stress on physiological traits in leaves of different rice varieties at seedling stage and the relationship with heat resistance to provide basis for breeding heat tolerant rice varieties. 【Method】Eight indica and eight japonica rice varieties were treated at conditions of control (28 ℃/22 ℃,day（07:00-19:00）/night（19:00-07:00）,CK) and heat stress (42 ℃/35 ℃,day（07:00-19:00）/night（19:00-07:00）,HS) at seedling stage.All varieties were classified to different heat tolerant degrees (highly tolerant,HT;moderately tolerant,MT;sensitive,S and mostly sensitive,MS) according to the survival rates under heat stress.The effects of heat stress on relative water content,chlorophyll content,reactive oxygen species (ROS) accumulation,membrane injury,antioxidant enzyme activity,osmotic adjustment substances and endogenous phytohormone content in leaves were also evaluated.【Result】Dongdao-4 (C10),Xiangliangyou-2 (C8),Huanghuazhan (C1) and Changbai-9 (C16) were highly tolerant rice varieties under heat stress condition with high seedlings survival rates.Xiangliangyou900 (C6),Taiyou390 (C7),Zhenghan-6 (C12),Wuyungeng21 (C11),Yuewangsimiao (C4) and Jigeng-515 (C13) were mostly sensitive varieties.Compared with CK,HS decreased contents of water,chlorophyll and endogenous IAA,Z+ZR and GA3 contents in rice leaf,while increased ROS accumulation,membrane injury (relative electrical conductivity and MDA content),antioxidant enzyme activities (SOD,POD,CAT and APX) and contents of osmotic adjustment substances (proline and soluble sugar) and endogenous ABA.The relative water content,chlorophyll content,SOD,POD and CAT activities,and endogenous ABA content in heat tolerant rice varieties were significantly higher than those in heat sensitive varieties,while ROS content,relative electrical conductivity and MDA content were significantly lower.There was no significant difference in APX activity,and contents of osmotic adjustment substances and endogenous IAA,Z+ZR and GA3 between heat tolerant and sensitive varieties.The ROS accumulation,antioxidant enzyme activity,membrane injury degree and endogenous ABA content were significantly correlated to survival rates of rice varieties,which could be used for screening heat tolerant varieties.【Conclusion】Heat stress induced over accumulation of ROS in leaves and resulted oxidative stress were main reason for leaf withering.Improving antioxidant defense capability and endogenous ABA signaling was an important pathway in rice for resisting heat stress,and it can be used as an important breeding strategy for heat tolerant rice resources. |
| Key words: rice heat stress stress physiology leaf physiological characteristics |
