Identification of Key Gene Networks Associated With Cell Wall Components Leading to Flesh Firmness in Watermelon

Abstract

Flesh firmness of watermelon is an important quality trait for commercial fruit values, including fruit storability, transportability, and shelf life. To date, knowledge of the gene networks underlying this trait is still limited. Herein, we used weighted genes co-expression network analysis (WGCNA) based on correlation and the association of phenotypic data (cell wall contents) with significantly differentially expressed genes between two materials, a near isogeneic line “HWF” (with high average flesh firmness) and inbred line “203Z” (with low average flesh firmness), to identify the gene networks responsible for changes in fruit flesh firmness. We identified three gene modules harboring 354 genes; these gene modules demonstrated significant correlation with water-soluble pectin, cellulose, hemicellulose, and protopectin. Based on intramodular significance, eight genes involved in cell wall biosynthesis and ethylene pathway are identified as hub genes within these modules. Among these genes, two genes, Cla012351 (Cellulose synthase) and Cla004251 (Pectinesterase), were significantly correlated with cellulose (r2 = 0.83) and protopectin (r2 = 0.81); three genes, Cla004120 (ERF1), Cla009966 (Cellulose synthase), and Cla006648 (Galactosyltransferase), had a significant correlation with water-soluble pectin (r2 = 0.91), cellulose (r2 = 0.9), and protopectin (r2 = 0.92); and three genes, Cla007092 (ERF2a), Cla004119 (probable glycosyltransferase), and Cla018816 (Xyloglucan endotransglucosylase/hydrolase), were correlated with hemicellulose (r2 = 0.85), cellulose (r2 = 0.8), and protopectin (r2 = 0.8). This study generated important insights of biosynthesis of a cell wall structure and ethylene signaling transduction pathway, the mechanism controlling the flesh firmness changes in watermelon, which provide a significant source to accelerate future functional analysis in watermelon to facilitate crop improvement.

Biostimulatory Action of Vegetal Protein Hydrolysate and the Configuration of Fruit Physicochemical Characteristics in Grafted Watermelon

“…A plethora of studies have identified pulp firmness as the quality trait most frequently and consistently improved by grafting commercial watermelon cultivars onto inter-specific hybrid rootstocks [22,35]. This effect is associated with increased fruit cell density and altered cell wall characteristics, and it is possibly related to the grafting-mediated differentiation of scion gene expression, which encompasses the over-regulation of cytokine and other metabolites of primary and secondary metabolism [36][37][38][39]. While flesh firmness may play a crucial role in watermelon quality and may also contribute to longer shelf life, the rind thickness of the watermelon fruit by rule affects the post-harvest management and postharvest performance of the fruit [9].…”

Full-length transcriptome sequencing reveals the molecular mechanism of potato seedlings responding to low-temperature

“…Pectin is an important component of plant cell wall and plays an important role in maintaining cell wall stability and resistance to adversity, accounting for 35% of the cell wall components of dicotyledons [ 81 ]. Pectinesterase (PME) mainly catalyze the demethylation of pectin to form pectic acid and methanol [ 82 ].…”

Pre-Anthesis Cytokinin Applications Increase Table Grape Berry Firmness by Modulating Cell Wall Polysaccharides

“…Regarding hemicellulose, epicarp and mesocarp tissues contain an increased amount of different XyG monosaccharides, suggesting that pre-anthesis CPPU applications could promote xyloglucan synthesis during grape berry development. Homogalacturonan is the pectinic domain of cell wall components most widely associated with firmness in different berry fruits [2,27,[50][51][52]. The analyses indicate that pre-anthesis CPPU applications induce an increased accumulation of GalA and cell wall-associated calcium than control samples in the mesocarp tissue.…”