基于BSA-seq的西瓜白色果皮基因定位分析OA

This study used the watermelon with white peel variety Sanbai Gua and the dark green peel material LN1-1 as parents to construct a genetic population,systematically dissect the genetic mechanism of white peel in watermelon,map the key genes regulating this trait,with the aim of providing a theoretical basis for molecular marker-assisted breeding of watermelon with white peel.Using Sanbai Gua as the female parent and LN1-1 as the male parent,a four-generation popu-lation was constructed.The peel color phenotype of the F2 population was investigated,and subjected to genetic analysis.Bulked segregant analysis combined with whole-genome resequencing(BSA-seq)technology was employed to sequence the extreme pools of white and non-white peel individuals in the F2 generation,and bioinformatics analysis was used to map key candidate genes,followed by sequence alignment and phylogenetic tree analysis to verify gene functional associ-ations.The results showed that among the 225 F2 plants,60 displayed white peel and 165 showed non-white peel,with a segregation ratio fitting the theoretical 1∶3 ratio(χ²=0.33,P>0.05),indicating that white peel trait is controlled by a single recessive nuclear gene.BSA-seq localized the gene to a 2.74 Mb interval on chromosome 9(11 793 001-14 532 000 bp),containing 78 genes,among which Cla97C09G175170(a homolog of APRR2)was predicted as the key candidate gene.Sequence analysis revealed no variation in the coding region of this gene,with only one critical G→A SNP within the 9th intron that co-segregated with the white/non-white phenotype.Phylogenetic tree analysis showed that its encoded protein is highly conserved with homologous protein sequences from other crops such as wax gourd,cucumber,and tomato.Com-bined with the known function of the APRR2 gene,it is speculated that this intronic mutation may affect gene expression,thereby impairing chloroplast development and leading to complete loss of chlorophyll,ultimately resulting in the white peel phenotype.This study successfully mapped and predicted Cla97C09G175170 as the key candidate gene controlling watermelon white peel,laying an important theoretical foundation for further gene functional validation,and molecular marker-assisted breeding.