澳洲坚果种质资源耐热性调查与分析

Investigation and analysis on heat tolerance of macadamia germplasm resources

随着全球气候变暖,在夏季持续高温干燥天气下,我国广东、广西澳洲坚果产区不耐热的澳洲坚果种质新梢叶片出现黄化现象,直接或间接影响光合作用,进而影响产量和品质。为了筛选耐热种质应对气候变化,以位于广东省湛江市的国家热带果树种质资源(澳洲坚果)圃内的145份种质资源为试材,调查不同种质的耐热性,分析比较不同程度热敏感种质的生理特性。结果表明,湛江地区6-7月下半昼(12:00-18:00)和上半夜(18:00-24:00)经历了6次较长时间的气温高峰和湿度低谷,导致热敏感种质新梢叶片黄化。不同种质新梢叶片黄化程度因其热敏感程度不同而异,供试145份种质可划分为耐热、轻度热敏感、中度热敏感、重度热敏感种质4类。随着种质热敏感程度的加剧,叶片的叶绿素(叶绿素a+叶绿素b、叶绿素a、叶绿素b)含量均显著下降而呈现褪绿黄化;超氧阴离子自由基(O_(2)^(-))大量积累,脂氧合酶(LOX)活性显著增强,丙二醛(MDA)含量显著增加,表明由活性氧积累引发的细胞膜脂过氧化加剧。与耐热种质相比,轻度热敏感种质的超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性显著增强;随着热敏感程度加剧,中度热敏感种质和重度热敏感种质的SOD活性均显著低于耐热种质,POD活性仍显著增强,而中度热敏感种质和重度热敏感种质的CAT活性无显著性差异,表明细胞抗氧化代谢失调。

With global warming,under the persistent high temperature and dry weather in summer,leaves yellowing occurred on the new shoots of heat-sensitive macadamia germplasm in the macadamia producing areas of Guangdong and Guangxi in China,which directly or indirectly affected photosynthesis,and consequently yield and quality.In order to screen heat-tolerant germplasm to cope with climate change,145 macadamia germplasm resources in the National Tropical Fruit Germplasm Resource Nursery located in Zhanjiang City,Guangdong Province,were used as materials to investigate the heat tolerance of different germplasm,and to analyze the physiological characteristics of germplasm with different degrees of heat sensitivity.The results showed that six longer time of high temperature and low humidity occurred in the afternoon(12:00-18:00)and the evening(18:00-24:00)from June to July in Zhanjiang City,resulting in leaves yellowing of new shoots of the heat-sensitive germplasm.The degree of leaves yellowing of new shoots varied with different heat-sensitivity of the germplasm.The 145 macadamia germplasm resources could be divided into four categories,including heat-resistant germplasm,slightly heat-sensitive germplasm,moderately heat-sensitive germplasm,and severely heat-sensitive germplasm.With the increase of the degree of heat sensitivity of germplasm,the contents of chlorophyll(chlorophyll a+chlorophyll b,chlorophyll a,chlorophyll b)in leaves decreased significantly,resulting in leaves yellowing.The large quantity of superoxide anion free radicals(O_(2)^(-))was accumulated,the activity of lipoxygenase(LOX)and the content of malondialdehyde(MDA)were significantly increased,indicating the intensified cell membrane lipid peroxidation caused by the accumulation of reactive oxygen species.Compared with heat-resistant germplasm,the activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT)were significantly increased in slightly heat-sensitive germplasm.As the degree of heat sensitivity aggravated,the SOD activity of moderately heat-sensitive germplasm and severely heat-sensitive germplasm was significantly lower than that of heat-resistant germplasm.The POD activity was still significantly enhanced,while there was no significant difference in CAT activity between moderately heat-sensitive germplasm and severely heat-sensitive germplasm,indicating the dysregulation of cellular antioxidant metabolism.