Genome-Wide Identification and Phylogenetic Analysis of Cell Wall Remodeling Genes in Carica papaya L.

Fruit softening in Carica papaya L. is a significant postharvest limitation, primarily driven by the dynamic remodeling of cell wall polysaccharides. In this study, we conducted a genome-wide identification and in silico characterization of gene families involved in cell wall assembly and disassembly in papaya. A total of 181 genes were identified and classified into metabolic pathways: hemicellulose (58), pectin (69), extensin (24), expansin (13), and cellulose (17). These genes encode 176 predicted proteins, ranging in size from 100 to 1093 amino acids, featuring family-specific catalytic domains, including glycosyl hydrolases, transferases, and serine/threonine kinases. Phylogenetic analyses revealed strong conservation within the expansin-A and pectin polygalacturonase subfamilies, while hemicellulose-related XTH genes exhibited significant diversification. Experimental validation of nine XTH members confirmed this diversification, with amplicons ranging from 322 to 1370 bp, consistent with computational predictions. Notably, CpXTH1 and CpXTH32 produced bands of approximately 1200 and 1400 bp, respectively. These findings underscore the complexity of papaya cell wall gene families and provide a molecular framework for understanding fruit softening. Given that postharvest losses of papaya in Mexico exceed 34.7% of production (approximately 150,000 tons annually), our results offer valuable genomic resources for biotechnological strategies aimed at extending shelf life and reducing economic losses.