Research On Mechanism Of Priming Improving The Vigor Of Aged Gourd Seeds

Seeds are the most fundamental materials for agricultural production. Stored seeds are always used in production practice. However, seeds will deteriorate inevitably during storage, which brings about huge losses to agricultural production. A number of studies have proved that vigor of aged seeds can be restored or improved after the priming treatment. To elucidate the mechanism, seeds produced by our own research group were used as experimental materials and artificially aged by58±1℃hot water. We managed to get a range of aged seeds with different vigor by controlling the aging time, namely0min,60min,90min,120min,180min. Priming treatment were applied to these seeds and germination test was conducted thereafter. Results showed that priming increased the germination energy, germination rate, germination index and vigor index of all the tested seeds. And this paper was expected to explore the mechanism of the favorable effects of seed priming from the following aspects.1. Priming treatment was applied to seeds with different vigor, and those unprimed were control. Results showed that, seed priming significantly slowed down the water absorption and the moisture content in seeds aged for0min,60min,90min,120min,180min was82%,83%,79%,78%,82%of that in seeds unprimed; priming also increased the respiratory rate of all the tested seeds, the respiratory rate in primed seeds were5to6folds of that in unprimed seeds; improved the activities of all those enzymes and up-regulated relative expression levels of MDH and SDH, except for the seeds aged for180min.2. Priming treatment was applied to seeds with different vigor, and those unprimed were control. Results showed that seed priming significantly lowered the MDA content of all the tested seeds, the MDA content decreased31.7%,31.9%,15.8%,16.6%,8.6%in seeds aged for0min,60min,90min,120min,180min after priming, and the MDA contents were also lower in primed seeds than unprimed seeds in germinating process. Priming significantly improved the activities of CAT、 SOD、GR、MDHAR; and up-regulated the relative expression levels of these genes.3. Priming treatment was applied to seeds with different vigor, and those unprimed were control. The radicle tip of seed embryo was used to do the flow cytometric analysis after the testa removed. And results showed that there were more cells with radicle tip entering G2phase after priming, which means priming can facilitate the cell cycle of aged seeds. Seeds aged for0min,60min and90min showed particularly significant advantage after priming.This paper found that the mechanism of priming improving the vigor of aged seeds was:firstly, priming enhanced the antioxidant system of aged of seeds. Activities of many antioxidant enzymes increased and those related genes were up-regulated which facilitated the ROS scavenging ability of seeds. And priming slowed down the water absorption of seeds, increased the respiratory rate, improved the activity of key enzymes and up-regulated the relative expression of SDH and MDH. Priming enhanced the respiratory metabolism, thus producing enough energy for other activities. And this paper also found that priming facilitated the cell cycle of seeds.