以45℃老化48d的超干燕麦种子(含水量4％)为材料,通过水势为0(蒸馏水)和-1.2 MPa的PEG6000在20℃黑暗条件引发12h后,分析其发芽率、发芽指数、平均发芽时间及幼苗活力指数,种胚细胞及线粒体的超微结构、超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)、谷胱甘肽还原酶(GR)和丙二醛(MDA)含量的变化,以探讨PEG引发对其萌发及幼苗生长、种胚细胞及线粒体结构和抗氧化性能的影响.结果表明:PEG引发提高了超干燕麦老化种胚细胞及其线粒体的SOD、APX及GR活性,其种胚细胞内SOD、APX和GR活性分别提高了26.7％、20.9％和26.9％,其线粒体内SOD、APX和GR活性分别提高了19.2％、19.4％和17.1％,使种胚细胞及线粒体内MDA含量分别降低了28.3％和13.7％,并维持了其正常的细胞及线粒体结构,从而促进其萌发.然而,蒸馏水引发则相反.种胚细胞与线粒体在超干燕麦老化种子的引发过程中具有协同性,且线粒体发挥着更重要的作用.%This study was designed to explore the effect of PEG priming on the seed germination,seedling growth,cellular and mitochondrial ultrastructure and oxidation resistance of aged oat (Avena sativa) seed embryos.Seeds with ultra-dry moisture content (4％) were deteriorated for 48 d at 45 ℃,and primed with either 0 (distilled water) or-1.2 MPa of PEG-6000 for 12 h at 20 ℃ under darkness conditions.Analysis was then undertaken to determine the seed germination percentage,germination index,mean germination time,seedling vigor index,cellular and mitochondrial ultrastructure and their superoxide dismutase (SOD),ascorbate peroxidase (APX),glutathione reductase (GR) and malondiadehyde (MDA).The results showed that the activities of cellular and mitochondrial SOD,APX and GR were increased by PEG priming in the embryo of ultra-dried and aged oat seeds.The activities of cellular SOD,APX and GR increased by 26.7％,20.9％ and 26.9％ respectively.The activities of mitochondrial SOD,APX and GR increased by 19.2％,19.4％ and 17.1％.MDA contents declined by 28.3 ％ and 13.7 ％,maintaining cellular and mitochondrial structures and hence promoting seed germination and seedling growth.However,the opposite changes were observed in seeds tested with distilled water priming.The ultrastructure and oxidation resistances showed a close and collaborative relationship between embryonic cells and their mitochondria in ultra-dried and aged oat seeds during the priming process,with the role of mitochondria more important than that of the embryonic cells.
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