【目的】从孕穗期到抽穗开花是水稻对温度最为敏感的阶段,这一阶段的低温冷害严重制约了东北地区水稻生长和种植面积的进一步扩大,探明水稻耐冷生理机制,将为东北水稻生产提供重要保障。探索耐冷性不同的杂草稻和栽培稻在冷水胁迫下开花期剑叶的活性氧代谢、抗氧化酶活性和抗氧化剂含量的变化规律,为耐冷性水稻品种的选育和栽培提供理论依据。【方法】以耐冷性强的杂草稻WR03-45、栽培稻丽江新团黑谷和冷敏感的杂草稻WR03-26、栽培稻秀子糯为试验材料,采用盆栽方法,根据剑叶叶枕距判断主穗进入孕穗期的时间,于孕穗期在冷水池中进行低温处理,未经冷水处理的参试材料作为对照。在开花期,剪取参试材料的剑叶保存于-85℃的超低温冰箱中,用于测定超氧阴离子自由基()产生速率、过氧化氢(H2O2)含量、丙二醛(MDA)含量以及超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)、抗坏血酸过氧化物酶(APX)和谷胱甘肽还原酶(GR)5种抗氧化酶活性和还原型抗坏血酸(AsA)、还原型谷胱甘肽(GSH)两种抗氧化剂含量,研究孕穗期低温冷害对剑叶的活性氧(ROS)积累、抗氧化酶活性和抗氧化剂含量的影响。【结果】冷水胁迫下,冷敏感的杂草稻WR03-26开花期剑叶仅有CAT和GR活性显著增加,冷敏感的栽培稻秀子糯开花期剑叶SOD、CAT和GR活性显著增加;WR03-26和秀子糯剑叶的AsA和GSH含量及AsA/DHA值和GSH/GSSG值与对照无显著差异;WR03-26和秀子糯剑叶产生速率显著增加,H2O2含量极显著增加,膜脂过氧化产物MDA含量显著增加。耐冷性强的杂草稻WR03-45开花期剑叶SOD活性显著升高,POD、APX、CAT和GR极显著升高,耐冷性强的栽培稻丽江新团黑谷开花期剑叶SOD、POD和APX活性显著升高,CAT和GR活性极显著升高;WR03-45和丽江新团黑谷剑叶的抗氧化剂(AsA和
【Objective】 Rice is most sensitive to temperature from booting stage to heading and flowering stages, so cold damage during this stages severely limited rice growth and the further expansion of acreage in Northeast China. Study on the physiological mechanism of rice cold tolerance will provide an important safeguard for the rice production in Northeast China. The aim of this study was to understand the changes of reactive oxygen species metabolism, antioxidant enzyme activities and antioxidants contents in flag leaves of weedy and cultivated rice with different chilling sensitivity at flowing stage under cold water stress, and provide a theoretical basis for the breeding and cultivation of rice tolerance to cold. 【Method】 Two chilling-tolerant genotypes, weedy rice WR03-45 and cultivated rice Lijiangxintuanheigu, and two chilling-sensitive genotypes, weedy rice WR03-26 and cultivated rice Xiuzinuo, were used and grown in plastic pots. The time of booting stage of main spike was calculated according to length of the flag leaf collar. The tested materials were subjected to low temperature in cold water pool at booting stage, and the control was the tested materials without cold water treatment. In order to study the effects of cold water stress on reactive oxygen species(ROS) metabolism, antioxidant enzyme activities and antioxidants contents of flag leaves at flowing stage, the flag leaves of tested materials were clipping and saved in ultra-low temperature freezer at-85 ℃, which were used to measure superoxide radical() generating rate, hydrogen peroxide(H2O2) content, malondialdehyde(MDA) content, activities of antioxidant enzymes of superoxide dismutase(SOD), guaiacol peroxidase(POD), catalase(CAT), ascorbate peroxidase(APX), glutathione reductase(GR) and non-enzymatic antioxidants contents of ascorbate acid(As A) and reduced glutathione(GSH). 【Result】 Under cold water stress, only CAT and GR activities in flag leaves of chilling-sensitive weedy rice WR0