Study On The Physiological Mechanism Of Rescuing Dying Purple-leaf Rice Germplasm By PEG Priming

The mechanism of seed vigor loss and restoration is related to the conservation of plant germplasm resources,which has been one of the research focuses in seed biology.Purple-leaf rice is a new landscape plant in recent years.It is widely used in sightseeing agriculture and has high ornamental and economic value.At present,the germplasm resources of purple leaf rice in China are mainly local varieties,which are preserved in the form of seeds.Due to the lack of cryopreservation facilities in farmers or breeders,seed viability is often too low and genetic integrity is lost during reproduction and regeneration.Therefore,to save the low vigor purple leaf rice seeds and to reveal its physiological mechanism can provide scientific basis for the protection and utilization of purple-leaf rice germplasm resources.In this study,the seed(germination rate was only 58%)of purple-leaf rice,a local variety in Jiangxi province,was used as the material.The seeds were treated with20% PEG-6000 solution for 12,24 and 48 h respectively,and the untreated seeds were used as control.The indexes of vitality,enzyme activity of antioxidant system,protein and gene expression,and genetic diversity index were analyzed.The main results were as follows:1.20% PEG-6000 solution priming treatment could improve the vigor of purple-leaf rice seeds and promote rapid germination.The germination rate,germination potential,germination index,average root length and vigor index increased by 23.34%,21.66%,1.92,0.04,1.52 cm,1.06,0.003.Priming significantly reduced the content of MDA in purple-leaf rice seeds and the relative conductivity of the extracts.2.The activities of SOD,CAT,APX,GR and MDHAR increased significantly in the treated seeds except DHAR.Except that the expression of Fe SOD and Mn SOD did not change significantly,the expression of CAT,APX and GR were consistent with the activity of enzyme.Priming treatment resulted in significantly up-regulated expression of 16 antioxidant enzyme genes and down-regulated expression of 6antioxidant enzyme genes.3.The number of alleles,effective alleles,Shannon index and Diversity Index of48-hour-old purple-leaf rice germplasm were significantly higher than those of the control.In conclusion,PEG priming can improve the viability,antioxidant system activity,and genetic diversity of dying purple-leaf rice seeds.These results can provide scientific basis for saving dying germplasm.