不同基因型小麦对热处理的响应

Response of Different Genotypes of Winter Wheat to Heat Treatment

为进一步揭示小麦耐热性的生理机制,以黄淮海地区正在推广的24个小麦品种(系)为材料,分析了不同小麦基因型苗期和生育后期细胞膜热稳定性和获得耐热性的差异。结果表明,不同品种(系)不同生育期耐热性差异较大,苗期热致死时间变化范围为13～50min;34℃高温诱导使热致死时间显著延长,变化范围变为50～200min,品种(系)间植株获得耐热性差异较大;大田条件下,灌浆期正常植株热致死时间与苗期相近,而成熟期随气温升高和生育进程热致死时间延长,变化范围为10～60min。开花后5～7d高温诱导能显著延长生育后期植株热致死时间,植株将获得耐热性,并一直保持至成熟期。25℃下正常生长植株的旗叶SOD和POD活性均随生育进程而升高;高温诱导使灌浆期SOD和POD活性分别升高和降低,同时抑制成熟期SOD和POD活性的进一步升高,且对POD活性作用更大,苗期获得耐热性强的品种(系)的抗氧化酶活性对高温诱导的反应明显。

Both the cytomembrane stability and the acquisition of heat-tolerance were studied by the changes of the amount of eletrolyte leakage treated with a sub-lethal high temperature in winter wheat,and the antioxidant enzymes activity were measured.The degree of heat-tolerance was presented by the duration of heat killing time at 50℃.The heat-tolerance of different varieties at different development stages was different.In seedlings,the duration of killing time was between 13～50 min,but it was much longer with the value between 50～200 min after acclimation at 34℃ for 3 days of seedlings.The acquired heat-tolerance was different among wheat varieties and could be maintained for at least two weeks.In the field environment,the duration of killing time was alike to that in seedling at grain-filling stage,and was longer at maturity stage with the rise of air temperature and the development process of plant.The duration of killing time at latter development stages could be increased by pre-treatment with a sub-lethal high temperature at earlier stage.Both the SOD and POD activities were highly increased with the process of development,and the SOD activity was increased but the POD activity was decreased by pre-treatment with a sub-lethal high temperature at earlier stage,and the further increase of both SOD and POD activities were inhibited at maturity stage.The inhibition was obvious in the varieties with stronger ability to acquisition of heat-tolerance.The results indicated that pre-treatment with a sub-lethal high temperature at earlier stage could abate oxidative damage,enhance cytomembrane stability and increase the ability of heat-tolerance to adapt to more severe heat stress in wheat.The antioxidant enzymes played important roles in regulating the process of acquisition of heat tolerance.