Physiological Characteristics,Agronomic Traits And Transcriptome Analysis Of OsDSR2 RNAi Transgenic Rice Under Salt Stress

Rice is one of the most important food crops in China and even in the world,and its also a model plant for functional genomics.The problem of soil salinization in Ningxia irrigation area is becoming more and more serious,obviously restricting the development of local agricultural production.The discovery of salt-tolerance(related)genes from rice and their introduction into cultivated rice to improve the salt-tolerance of rice is conducive to improving the utilization of saline-alkali land and improving the yield of rice.Our previous study confirmed that OsDSR2 gene was a salt-tolerant gene in rice and phenotypic identification was carried out with the obtained OsDSR2 RNAi transgenic rice,proved that the genetic material could improve the salt tolerance of rice seedlings.In order to further study the mechanism of OsDSR2 gene regulating the salt-tolerance of rice,this study studied the physiological characteristics and transcriptome analysis of OsDSR2 RNAi transgenic rice under salt stress using OsDSR2 RNAi transgenic rice as the material,and investigated the agronomic characteristics of the material through pot experiments.The main research results are as follows:1.Under normal conditions,zhonghuall(ZH11)and OsDSR2 RNAi transgenic rice in there is no significant difference between various physiological indexes,and salt stress,OsDSRl RNAi transgenic rice in the content of chlorophyll,soluble sugar(SS)content,superoxide dismutase(SOD)activity and catalase(CAT)activity compared with ZHI1 no obvious change,but the transgenic plants of cell membrane permeability,malondialdehyde(MDA)content and Na+/K+ratio significantly below ZHI1,Proline(Pro)content and peroxidase(POD)activity were significantly higher than ZH11.On the physiological level,OsDSR2 RNAi transgenic rice plants can improve salt tolerance of seedling rice plants mainly by reducing cell membrane permeability,MDA content and Na+/K+ratio,and increasing Pro and POD activities.2.OsDSR2 RNAi transgenic plants produced 58 differentially expressed genes before and after salt stress,among which 55 genes were up-regulated and 3 genes were down-regulated.The results of GO analysis showed that the differentially expressed genes were mainly enriched in stress response,catabolic metabolism and other biological processes.Through RT-qPCR,OsbZIP16,OsLEA3,RAB21 and other stress-related genes were further verified to participate in the stress response of rice.The results of KEGG analysis showed that the differentially expressed genes were mainly involved in the biosynthesis of carotenoids,brassinolactone and the biosynthesis of epidermal,cork and wax biosynthesis pathways.3.Under normal conditions,the number of Panicle per plant and grain weight per plant of OsDSR2 RNAi transgenic rice were significantly lower than ZH11,and the number of Panicle per plant of OsDSR2 RNAi transgenic rice was significantly higher than ZH11 after salt stress treatment,but there was no significant difference in grain weight per plant between the two planting strains.Under normal conditions,OsDSR2 RNAi transgenic rice and ZH11 had no significant difference in seed setting rate,and the number of Panicle per plant and seed setting rate of OsDSR2 RNAi transgenic rice after salt stress were significantly higher than that of ZH11.Compared with normal conditions,the 1000-grain weight of OsDSR2 RNAi transgenic plants under salt stress was negatively correlated with the number of grains per panicle,and the grain weight and seed setting rate per plant decreased with the increase of total grains per panicle.OsDSR2 RNAi transgenic plants treated with salt stress had the largest eigenvectors of grain weight and seed setting rate per plant.In conclusion,compared with ZH11,OsDSR2 RNAi trransgenic rice plants can improve the salt tolerance of seedling rice plants mainly by reducing cell membrane permeability,MDA content and Na+/K+ratio,and increasing Pro and POD activity.At the molecular level,OsDSR2 may be involved in the regulation of OsLEA 3,RAB21,OsbZIP16 and other stress-related genes through ABA(abscisic acid)and BR(brassinolide)signaling pathways,as well as the expression of plant epidermal wax biosynthesis related genes(LOC_Os04g28620)to improve salt tolerance of rice in seedling stage.In terms of agronomic traits,the interference expression of OsDSR2 can inhibit the reduction of panicle number,seed setting rate and grain weight per plant in rice plants and improve the effects of grain weight per plant and seed setting rate on rice yield,these can mitigate the loss of rice yield under salt stress.