花生种子萌发早期胚轴DNA合成与种子活力的关系

Studies on the Correlation Between Seed Vigour and DNA Synthesis in the Axis of Peanut Seed During Early Germination

随着花生种子萌发率和活力指数的下降,胚轴DNA开始合成的时间推迟,其合成水平也降低。但DNA合成都是先于吸胀的12h(高活力胚)或18h(低活力胚)出现一个峰,然后再持续上升。腐胺预处理明显地促进老化胚轴萌发早期(12～2dh)的DNA合成。钙离子预处理则有一定抑制作用,但两种预处理均能提高种子的活力指数,并能促进吸胀30h以后的DNA合成。

It was found that the incorporation of ~3H-thymidine into DNA of embryos during early germination of peanut seeds reflected DNA repair and was related to seed vigour. The aim of this paper was to understand the role of DNA damage in the deterioration of seeds. The experimental materials used were seeds of cv. 'Yue-you 116' of peanut (Arachis hypogaea L.). The correlation between seed vigour and DNA synthesis in axis during early germination was studied by following the rate of the incorporation of ~3H-thymidine into TCA-precipetated substances.As germination percentage and seed vigour decreased, the peak of DNA synthesis in axis also decreased (from 12 h to 18 h of imbibition)(Fig. 2). When aged seeds were treated with Ca^(2+) or putrescine and allowed to imbibe for 0～6h, the germination percentage and vigour index increased. The effect of Ca^(2+) or putrescine on the uptake of ~3H-thymidine was insignificant. However, the incorporation of ~3H-thymidine into DNA of axis was greatly affected by Ca^(2+) or putrescine treatment. The peak of DNA synthesis in the axes of low vigour seeds was raised by putrescine but reduced by Ca^(2+) treatment during 12～18h of imbibition, and the replication of DNA in the axis could be accelerated by putrescine of Ca^(2+) treatment during the later stage of germination (after 30 h of imbibition) (Fig. 3). It seems that the DNA synthesis in the axes of peanut seeds during early germination is different to the DNA replication, which may be related to seed vigour and the extent of DNA damage in axis. The DNA damage in the axes of seeds with high germination percentage may be repaired successfully, but whether the DNA damage in the axes of aged seeds can be fully repaired needs further study.