Effect Of Polyamine On Seed Germination Of Wheat Under Drought And Mechanism Research

In the arid and semi-arid area of north China, drought is a major restriction on wheat seed germination and production. There is important significance to icrease drought resistance at the seed germination stage which improving the seed germination rate, increasing wheat production. Previous studies have shown that polyamine significantly impacts seed germination and the drought resistance of plants. Nevertheless, how polyamine interact with other hormones to regulation seed germination is still unknown. Based on the preliminary screening of different drought resistance of wheat varieties, we tested polyamine changes in the process of seed germination under different drought stress by using PEG-6000. Changes of some relative plant hormones, starch and soluble sugar content and peroxidase activities were also tested to illustrate polyamine effects on drought resistance by applying exogenous polyamine. The main results and conclusions are as follows:1.Endogenous polyamines are involved in the wheat seed germination responsing to drought stress. As seed germination, the free state, as well as the combination of soluble Spd and Put content increased, the insoluble combination patterns Spd and Put content increased first and then down. The Spd and Put content in response to drought stress have significant genotype differences. The free Spd accumulation in seeds during the seed germination period favored wheat seed germination under drought stress; however, the free Put accumulation in seeds during the seed germination period may work against wheat seed germination under drought stress.2.Exogenous polyamine PAs obviously influence the germination of wheat seed. Seed soaking in Spd and Spm significantly relieved the inhibition of seed germination by drought stress for example improving the wheat seed germination rate, promoting the coleoptile of wheat seeds and radicle growth; however, soaking seeds in Put had no significant effect on seed germination under drought.3.In the process of seed germination, exogenous polyamine PAs can significantly affect endogenous hormone content in the seeds. With the increase of PEG-6000 concentration, GAs, IAA and Z + ZR content in seeds decreased and ABA content increased. Under the condition of drought stress, GAs, IAA and Z+ZR content showed significant differences between wheat varieties of Changhan58 and Luomai18 which showed no difference under normal water condition. External Spd and Spm significantly increased the endogenous IAA, Z+ZR, ABA and GAs contents in seeds. Exogenous Put significantly increased IAA and ABA content of seeds but not GAs and Z + ZR content. Under normal water condition, Put, Spd and Spm treatment showed no influence on ABA content.4.Drought stress decreased seed total soluble sugar concentration and increased the concentration of starch in seeds. In the process of seed germination, the exogenous and Spd and Spm significantly increased seed total soluble sugar concentration and reduced seed starch concentration. However, exogenous Put has no effect on seed soluble sugar and starch concentration.5.Drought stress decreased peroxidase(POD), catalase(CAT), superoxide dismutase(SOD) activity and improved the malondialdehyde(MDA) content. Exogenous spermidine(SPD) and spermine(Spm) significantly increased peroxidase(POD), catalase(CAT), superoxide dismutase(SOD) activity and decreased malondialdehyde(MDA) content under drought germinating seeds. By contrast, exogenous putrescine P1(put) treatment significantly reduced peroxidase(POD), catalase(CAT) and superoxide dismutase(SOD) activity, increased malondialdehyde(MDA) content.