Identifying Candidate Genes for Grape (Vitis vinifera L.) Fruit Firmness through Genome-Wide Association Studies

The firmness of grape berries is a critical factor influencing
their commercial feasibility and is highly valued by both breeders
and consumers. However, grape berry firmness is a complex quantitative
trait governed by multiple genes, and our understanding of its genetic
regulatory network remains incomplete. To elucidate the genetic mechanisms
underlying grape berry firmness, this study employed genome-wide association
studies (GWAS) to identify potential candidate genes associated with
fruit firmness and cellulose content and to explore the gene regulatory
network that controls their variation. The comprehensive GWAS results
identified CesA as a candidate gene potentially regulating
fruit firmness through its involvement in cellulose biosynthesis.
To validate these findings, whole-genome gene family identification
analysis was conducted. Furthermore, the key gene VvCslD5 was selected for functional validation, which included overexpression
studies and subcellular localization. This study provides valuable
insights into the regulation of biosynthesis and transcriptional signaling
pathways that govern the structure of grape cell walls as well as
the mechanisms underlying variations in grape firmness. These findings
establish a solid foundation for future functional analyses of grape
traits and will enhance breeding practices aimed at improving grape
quality.