Mining of candidate genes related to total solid in latex of Hevea brasiliensis 1981'IRRDB germplasm based on genome-wide association analysis

【Objective】 This study aimed to conduct genome-wide association analysis of total solid of latex of Hevea brasiliensis 1981'IRRDB germplasm and mine candidate genes， providing theoretical basis for elucidating the molecular mechanism of rubber production to improving latex production and flow ability of Hevea brasiliensis 1981'IRRDB germplasm. 【Method】 A total of 198 Hevea brasiliensis 1981'IRRDB germplasm resources were taken as research objects， and the Hevea brasiliensis germplasm resources were tapped and the yield was measured from 2022 to 2024. The total solid content of latex in the final tapping was measured， and the best linear unbiased estimator （BLUE） and best linear un-biased prediction （BLUP） were analyzed. The DNA from young leaf samples of Hevea brasiliensis 1981'IRRDB germplasm was resequenced. Genome-wide association analysis was performed using the BLUE of total solid content over three years to detect SNP loci in the population and screen for significant SNP loci. Candidate genes were screened based on transcriptome data. The candidate genes were subjected to GO functional annotation， KEGG signaling pathway enrichment analysis， protein interaction prediction， and linkage disequilibrium analysis to identify key candidate genes. 【Result】 From 2022 to 2024， the coefficient of variation for total solid content ranged from 18.62% to 25.01%. The coefficients of variation for BLUE and BLUP of total solid content were 13.48% and 2.63% respectively， with all traits exhibi-ting normal or skewed normal distribution. A total of 4915181 SNP loci were identified from the resequencing data of 198 Hevea brasiliensis 1981'IRRDB germplasms and were used for genome-wide association analysis. Through genome-wide association analysis for total solid content， 15 significant SNP loci and 73 candidate genes were screened. Candidate genes were mainly enriched in GO functional terms such as response to stimulus， response to chemical， and response to organic substance stimulu and KEGG signaling pathways such as biosynthesis of secondary metabolites， flavonoid， and cyanoamino acid. Based on transcriptome expression analysis of different tissues， protein interaction prediction， and linkage disequilibrium analysis， 4 genes （HB11G016650， HB13G002880， HB14G037800， and HB16G006890） were screened as key candidate genes. These genes belonged to the auxin response factor （ARF）， integrator complex （INTS）， abscisic acid receptor protein （PYL8）， and dirigent protein （DP） gene families respectively. Linkage disequilibrium analysis revealed significant differences in total solid content among different haplotypes of the SNP loci within these 4 key candidate genes. 【Conclusion】 In 198 Hevea brasiliensis 1981'IRRDB germplasms， 15 significant SNP loci associated with total solid content are identified， and 4 candidate genes related to latex flow capacity are mined. Among these， ARF is probably a key gene regulating the processes of latex production and flow for rubber.