Identification Of Key Candidate Sites For High Temperature In Rice Seedling Stage

Crops have different requirements on the ambient temperature in different growth and development stages.Exceeding or inadequate temperatures corresponding to the growth and development of the crop will cause the crop to face varying degrees of yield reduction.High temperature stress has become an important factor affecting crop yield because of global warming.The main way to reduce the negative impact of high temperature stress on crop yields is to study the candidate interval in crops in response to high temperature stress,and then accurately locate the heat-resistant genes.As an important food crop,the abnormally high temperature in the early stages of growth will directly affect the normal growth and development of rice.Some scholars have determined that the rice materials 93-11 and PA64 s are different.The recombined inbred lines of the two hybrids recombine well,and both carry different fragments of their parents.Another scholar has completed 3010 rice sequencing tasks.Based on this,the subject focused on the effects of high temperature stress on rice seedlings,and selected 255 core germplasm resources in each indica group from 124 RIL materials with different genotypes and 3010 parts of rice germplasm materials.While performing correlation analysis,the gene expression levels of heat-tolerant and non-heat-tolerant rice cultivars at the seedling stage will be analyzed to further determine candidate genes for rice seedlings,providing evidence for the selection of high-temperature-resistant rice materials.The specific research results are as follows:1.Biomass traits of different populations at seedling stage: This study counted three biomass traits of plant height,dry weight,and fresh weight of the seedlings before and after heat treatment in the RIL and natural indica rice populations.The average and extreme values of various traits of RIL and natural populations decreased after heat stress treatment,which confirmed that heat stress in rice seedlings had a negative impact on rice growth.Exploring heat-resistant QTLs in rice seedlings was important for stabilizing rice seedling growth.2.RIL linkage analysis: Based on the high-resolution genetic map of SNPs drawn by RIL sequencing,this study performed QTL mapping of 124 RIL material traits before and after heat stress treatment.A total of 20 QTLs were identified on chromosomes 2,3,4,6,7,9,11 and 12.Among them,10 biomass-related QTLs were identified in the biomass traits in the control group,and 8 QTLs were identified in the biomass traits in the test group under high temperature stress.In addition,after performing linkage analysis on the survival traits of the test group,one QTL was identified on each of chromosomes 3 and 9.3.Whole-genome association analysis of natural indica rice population: This study used 14,779,691 SNPs covering the entire genome to perform association analysis on 255 natural indica rice.There were significant differences in the candidate intervals of the biomass traits between the test group and the control group.There were loci that responded to high temperature stress in rice seedlings in different candidate intervals.These loci responded to high temperature stress by coordinating the biomass of rice seedlings.In the control group,this study identified 10 candidate intervals for biomass traits.Correlation analysis was performed on biomass traits and survival rates in the test group.We identified 106 candidate intervals,including 29 candidate intervals identified by biomass traits and 77 candidate intervals identified by survival traits.4.Extreme survival material transcriptome analysis: In order to further identify candidate sites for rice to respond to high temperature at seedling stage,this study selected two heat-resistant varieties and two heat-sensitive varieties in the natural indica rice population for transcriptome analysis.After comparing the gene expression between the heattolerant group and the heat-sensitive group,it was determined that a total of 529 genes were differentially expressed in the four groups,and it is believed that there are key genes in response to high temperature stress in rice seedlings.5.Joint identification of candidate intervals and loci in response to high temperature stress at the seedling stage of rice: Three types of analysis methods used in this study-linkage analysis,association analysis,and transcriptome analysis were used to compare and analyze the results to further enrich and improve the experimental results.We have identified 23 genes that can be identified in the results of two or more analysis methods as candidate genes,combined with homology analysis and known gene information,and identified some candidate genes that can be focused on in subsequent studies.To provide a reference for the cloning and molecular breeding of heat-resistant genes in rice.