ASHS 2024 Conference

Avocado (Persea americana) is renowned for its high nutritional value and its global consumption is steadily increasing. Currently, only a few cultivars with limited genetic variability are cultivated, and there is a need for developing new avocado cultivars with enhanced horticultural, fruit quality and nutritional traits as well as resistance to diseases and pests. Application of marker assisted selection can significantly accelerate breeding new avocado varieties, which can take 15 - 20 years using traditional breeding methods. Towards the application of molecular markers in avocado breeding, in this report, genome-wide association studies (GWAS) of nine fruit quality traits of a diversity panel of 110 avocado accessions were explored using 4,706 high-quality single nucleotide polymorphisms (SNPs) using multiple models. In addition, genetic diversity and population structure were also investigated, which unveiled three main populations corresponding to the three major avocado botanical races representing Mexican, West Indian, and Guatemalan ecotypes. Phylogenetic study and quantitative genetic analyses suggested a closer relationship between the Guatemalan and West Indian races compared to the Mexican race. Genome-wide association study revealed twelve markers distributed over eleven genomic regions strongly associated with fruit quality traits including fruit color, shape, taste, and skin texture. Annotation analyses of these genomic regions revealed candidate genes affecting these traits. These findings contribute to a comprehensive understanding of the genetic composition of avocado germplasm, which will be useful for identifying genes governing fruit quality traits as well as for accelerating breeding and parent selection efforts in the avocado breeding pipeline.