Studies On The Physiological And Biochemical Mechanisms And The Proteins Relative To Deterioration Of Rice Seeds

Seed is one of the most basic production means of human beings.The quality of seeds conditions the capacity of agricultural production,while seeds often undergo an irreversible declining of quality——deterioration or aging after reaching physiological maturity,which will result in a huge economic loss to the crop production.Therefore,it will have an important role for evaluating and regulating seed quality to clear the mechanism of seed deterioration.In this paper,the physiological and biochemical mechanisms were investigated of seed deterioration of two traditional rice cultivars 99-Zao-677,Xiang-Zao-Xian 24;And two hybride rice combinations Zhu-Liang-You 02,Zhu-Liang-You 819.For Zhu-Liang-You 819,the embryo proteins respectively extracted from high vigor seeds and low vigor seeds were compared and identified with bioinformational method.The results showed below:1.The anti-aging ability of hybrid rice seeds is weaker than that of traditional rice seeds.Under the condition of 40±1℃,and 99%of relative humidity(RH),artificially aged for 5 and 6 days respectively,the seed germination percentage of Zhu-Liang-You 02 and Zhu-Liang-You 819 dropped to 50%;Aged for 11 days,the viability of seeds of both hybrid combinations lost absolutely.While to the traditional rice 99-Zao-677 and Xiang-Zao-Xian 24,the aging time for the seed germination percentage dropped to 50%was 9 and 10 days respectively,the aging time for seeds lost viability was 13 days.2.There showed a negative correlation between the vigor of rice seeds and the permeability of cell membrane of them.Take the relative conductivity of the soaked solution of excoriated seeds as the permeability index of cell membrane,the lower the seed vigor was,the greater the relative conductivity was.Compared with the traditional rice seeds',the cell membrane structure of hybrid rice seeds was more vulnerable under the stress of deterioration.3.The CAT activity of hybrid rice seed with high vigor was higher than that of traditional rice high vigor seeds,i.e.,the CAT activity of Zhu-Liang-You 819 and Zhu-Liang-You 02 was 3.08 mg.g^-1min^-1and 3.42 mg.g^-1min^-1respectively;while to 99-Zao-677 and Xiang-Zao-Xian 24,it was 2.23 mg.g^-1min^-1and 2.13 mg.g^-1min^-1respectively).However,under deterioration,the CAT activity of hybrid rice seeds declined rapidly than that of traditional rice seeds.4.Whether traditional rice seeds or hybrid rice seeds,the high-vigor seeds have higher protein content and lower free amino acid content;with the progress of aging,the protein content in seeds decreased,and the content of free amino acids relevantly increased.5.The 2-DE protein maps of the embryos of high-vigor seeds and low-vigor seeds of Zhu-Liang-You 819 are obtained respectively by optimizing crucial factors such as sample treatment(proper lysis solution to treating samples,choosing moderate amount of sample,using pre-cast immobilized linear dry strips for the first dimensional electrophoresis), electrophoresis parameters,and gel concentration(12.5%separation gel and 4.8%concentration gel used in the SDS-PAGE electrophoresis).17 protein spots which show significant diversity between those two vigor-level seeds were identified by MALDI-TOF-MS and the bioinformationics of these proteins were then analyzed.Protein(pI 6.78,MW 52376 Da),(pI 6.53, MW 15263 Da)and(pI 5.16,MW 46197 Da)got the matched information. The results showed some of these proteins should be involved in respiration.