The Effect Of Gibberellin Pretreatment On Active Oxygen Metabolism, Sugar Metabolismglyoxylate Cycle Of Watermelon Seed During Germination

Watermelon(Citrullus lanatus), a crop under the citrullus genus, Cucurbitaceae family, is a very common fruit in daily life and one of the important cash crops in modern agricultural production. Gibberellin is a frequently used pant hormone. Researchers have found that Gibberellin could promote the seeds of multiple plants to break dormancy and germinate in advance. Watermelon seeds have high content of lipids, and their metabolism is closely related to the vitality of seeds. Studying the influence of gibberellin on the metabolism of lipids in the germination process of watermelon seeds could offer theoretical grounds for future researches into the mechanism of watermelon seeds‘ dormancy and germination process. Using ?Zaojia 8424‘Watermelon as the sample, this research selected a better gibberellin processing concentration and discussed gibberellin treatment‘s influence on the active oxygen scavenging system, the content of soluble sugar and the glyoxylate cycle in the germination process of Watermelon seeds which the treat time is 24 h. The results of the experiment are set out below:1. Gibberellin of different concentration levels was used to treat the Watermelon seeds. Upon selection, the optimal treatment concentration was determined as 300 mg L-1. Using the gibberellin at this concentration for the treatment of Watermelon seeds could reduce the electric conductivity of the seed leaching solution and increase the germination percentage, germination index and germination energy of the seeds while the germination energy, rate and index of seeds were 43%, 3.6%, 14.3% higher than before.2. After gibberellin treatment, in the active oxygen scavenging system, except that the activity of catalase(CAT) decreased at 0d, the activity of CAT-containing antioxidant enzymes, such as the APX, POD, SOD, GR and DHAR all increased at different stages. The contents of GSH and AsA rose in different stages. GSH/GSSG, AsA/DHA increased. All these reduce the production of MDA, relieving the harm to cells caused by hyper oxide in the oxidizing reaction process, so seed vigor increased.3. After gibberellin treatment, the activity of ICL and MDH inside the Watermelon seeds increased during the germination process, accelerating the response speed of the glyoxylate cycle and thus the metabolism of fatty acid, therefore, more malic acid will be produced.4. After gibberellin treatment, PEPC achieved the maximum activity in advance, increasing the glycolysis speed of sugar, accelerating the consumption of cane sugar inside the seeds, promoting citric acid to rapidly transform to isocitric acid upon short-term accumulation. The activity of SDH increased and the IDH achieved the maximum activity in advance, accelerating the overall speed of tricarboxylic acid cycle(TCA cycle). The succinate acid generated by glyoxylate cycle entered into the tricarboxylic acid cycle and the oxaloacetic acid produced in the TCA cycle entered into the gluconeogenic pathway. The activity of PEPCK increased significantly, with the activity of PEPC/PEPCK not rising, accelerating the gluconeogenic speed and increasing the content of glucose in the seedlings. This offers more energy for the seeds during germination, and also one of the reasons why seed vigor increase.