Analysis Of Differentially Expressed Genes In Rice Under Heat Stress And Heat And Drought Combined Stresses

Rice(Oryza sativa L.)is the main food crop that is consumed by about 50% of the world’s population.The growth of rice is restricted by a variety of environmental factors,including biotic stresses and abiotic stresses.Among them,abiotic stress is an important limiting factor affecting the development,growth and yield of rice.Rice is very sensitive to changing environments.It responds to changes in the environment by regulating gene expression,and ultimately physiology and metabolism.In this study,the microarray technology platform was used to analyze the transcriptome data of the 5-6 stage young panicles of different heat-tolerant rice varieties under high temperature stress;the differentially expressed genes in rice anthers under heat stress and combined heat and drought stress were screened and analyzed for their function enrichment;and screened the candidate rice cytochrome P450 family genes for expression analysis under different stresses.The major results are as followed:1.In this study,using heat tolerance line 996 and heat sensitive line 4628 as materials,microarray analysis was performed on the RNA extracted from the 5-6stage young panicles treated with high temperature of 40℃ for 0 min,10 min,20 min,60 min and 2 h.The results showed that the differentially expressed genes of two different varieties under high temperature stress were significantly enriched in phenylpropane biosynthesis,heat shock protein,tetratricopeptide repeat,and some processes related to abiotic stress.In addition,heat tolerance line 996 differentially expressed genes were also significantly enriched in oxalate metabolism,oxalate decarboxylase activity,manganese ion binding,germin and cytochrome P450.The heat sensitive rice 4628 differentially expressed genes were significantly enriched in pentatricopeptide repeat.This information will be useful for the identification of heat tolerant related genes and characterization of heat tolerant mechanism.2.The gene expression profile data in rice anthers under heat stress and combined heat and drought stresses were collected through domestic and foreign database resources and literature resources.The differentially expressed genes under heat stress and combined heat and drought stresses were screened and analyzed for their function enrichment.The results showed that differentially expressed genes in rice anthers under both heat stress and combined heat and drought stresses were significantly enriched in some basic and stress-related biological processes and metabolic pathways.They are involved in signal transduction,hormone response,lipid biosynthesis and metabolism.In addition,they are also enriched in heat shock proteins and molecular chaperone related protein domains.Under high temperature stress,differentially expressed genes in rice anthers were also significantly enriched in sphingolipid biosynthesis and metabolism,brassinosterol biosynthesis and metabolism,trehalose synthesis and metabolism,EF hand domain and enzymes related to fatty acid synthesis and metabolism;under the combined heat and drought stress,the differentially expressed genes in anthers were significantly enriched in abscisic acid response,PSII-related light-harvesting complex II decomposition process,and glycoside hydrolase superfamily.Stress tolerance-related genes can be effectively screened by functional enrichment analysis,which provides a certain theoretical basis for further screening of rice varieties with stress tolerance.3.Four rice cytochrome P450 family genes,including Os CYP90A3,Os CYP734A4,Os CYP90B2 and Os CYP707A5,were screened by functional enrichment analysis of differentially expressed genes in rice anthers of different heat-tolerant rice varieties under high temperature stress and combined heat and drought stresses.The expression levels of the above four rice cytochrome P450 family genes under three abiotic stress treatments of drought(10% PEG6000 simulation),high temperature(42℃)and salt(200 m M)were analyzed by q RT-PCR technology.The results showed that the four candidate rice cytochrome P450 family genes have certain responses to drought,high temperature and salt stresses.This indicated that the cytochrome P450 family genes involved in the synthesis and metabolism of brassinosteroids may play an important role under abiotic stress in rice.