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以玉米单交种郑单958和先玉335为试验材料,采用老化箱加速种子老化。随着种子老化时间的延长,郑单958和先玉335种子的发芽率、发芽指数、活力指数逐渐降低,老化至8 d,种子活力指标降至极低的水平。过氧化物酶、过氧化氢酶活力逐渐降低,电导率、丙二醛含量逐渐升高。MSAP分子标记扩增出2 750条有效峰值,随老化时间的延长,郑单958的CG甲基化水平呈现出逐渐降低的趋势,先玉335的CG甲基化水平逐渐升高。基因组DNA的CHG与CHG+CG甲基化水平变化不规律,郑单958基因组DNA的CHG和CG+CHG甲基化均高于对照,先玉335基因组DNA的CHG甲基化均低于对照。郑单958和先玉335的DNA发生甲基化模式变异,郑单958 DNA的CG去甲基化模式变异高于超甲基化,先玉335DNA的CG去甲基化模式变异低于超甲基化。相关性分析表明,种子的活力指标、生理指标与基因组DNA的CG甲基化相关系数较高。
Zhengdan 958 and Xiangyu 335 were used as experimental materials to accelerate the seed aging. With the prolongation of seed aging, the germination rate, germination index and vitality index of Zhengdan 958 and Xianxu 335 seeds decreased gradually. When the seeds were aged for 8 days, the seed vigor index dropped to a very low level. Peroxidase, catalase activity decreased gradually, conductivity, MDA content gradually increased. MSAP molecular markers amplified 2 750 effective peak, with the aging time, Zheng Dan 958 CG methylation showed a trend of gradually decreased, Xiangyu 335 CG methylation levels gradually increased. Genomic DNA CHG and CHG + CG methylation levels of irregular change, Zheng Dan 958 genomic DNA CHG and CG + CHG methylation were higher than the control, Xiangyu 335 genomic DNA CHG methylation were lower than the control. The variation of DNA methylation patterns in Zhengdan 958 and Xiangyu 335 was higher than that in hypermethylation in Zhengdan 958 DNA. The CG demethylation pattern in Xiangyu 958 DNA was lower than that in super-methylation Based on. Correlation analysis showed that the seed vigor index, physiological indicators and genomic DNA CG methylation correlation coefficient higher.