Genome-Wide Association Study to Identify Favorable SNP Allelic Variations and Candidate Genes That Control the Timing of Spring Bud Flush of Tea (Camellia sinensis) Using SLAF-seq.

The timing of spring bud flush (TBF) is of economic importance for tea plant (Camellia sinensis) breeding. We employed a genome-wide association study (GWAS) to identify favorable single nucleotide polymorphism (SNP) allelic variations as well as candidate genes that control TBF of C. sinensis using specific-locus-amplified fragment sequencing (SLAF-seq) in a diversity panel comprising 151 tea plant germplasm resources. GWAS analysis revealed 26 SNPs associated with TBF in three years, and we eventually identified a final significant SNP for TBF. To identify candidate genes possibly related to TBF, we screened seven candidate genes within 100 kb regions surrounding the trait-related SNP loci. Furthermore, the favorable allelic variation, the "TT" genotype in the SNP loci, was discovered, and a derived cleaved amplified polymorphism (dCAPS) marker was designed that cosegregated with TBF, which could be used for marker-assisted selection (MAS) breeding in C. sinensis. The results obtained from this study can provide a theoretical and applied basis for the MAS of early breeding in tea plants in the future.