人工老化玉米种子活力指标、生理指标与基因组DNA甲基化变异的研究

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。

Analysis of Artificical Aging Maize Seed Vigor and Physiological Index Related to Genome DNA Methylation Variation

Seeds of two hybrid cultivars Zhengdan958 and Xianyu335 were artificially aged by artificial aging chamber. Germination rate, vigor index, germination index were reduced gradually along the seed aging. Seeds of two hybrid cultivar germination rate, vigor index and germination index were dropped to the extremely low level when aged eight days. Peroxidase activities, catalase activities of Zhengdan958 and Xianyu335 reduced gradually while malonaldehyde content and conductance raised gradually. The 2 750 amplified effective peak value by MSAP biomarker showed that Zhengdan958 CG methylation level reduced gradually followed seed aging. While the CG methylation level of Xianyu335 got higher gradually. Seeds genome DNA CHG and CG+CHG methylation level changed have no regulation. Zhengdan958 genome DNA CHG and CG+CHG methylation were higher than contrast. Xianyu335 genome DNA CHG methylation was lower than contrast. Zhengdan958 and Xianyu335 DNA occurred methylation mode variation. Zhengdan958 genome DNA CG hypo mode variation was higher than hyper. While Xanyu335 DNA CG hyper mode variation was lower than hyper. The correlation analysis of seed vigor index with DNA methylation level showed that seed vigor indexes and Physiological indexes have a higher correlation with DNA CG methylation level.