N-Acetyl-d-glucosamine Inhibition of Hexokinase Results in Downregulation of the Phenylpropanoid Metabolic Pathway and Decreased Resistance to Brown Rot in Peach Fruit

Abstract

To explore the role of hexokinase (HXK) on disease resistance in peach fruit, peaches were treated with N-acetyl-d-glucosamine (NAG), a known HXK inhibitor, and then inoculated with Monilinia fructicola. We demonstrate that NAG significantly inhibits HXK activity, which in turn results in significantly reduced resistance to M. fructicola infection. In the HXK-inhibited fruit, the sucrose content was higher and the glucose and fructose contents were lower than in the control fruit. By transcriptome analysis, we found 347 differentially expressed genes (DEGs) between NAG-treated and control peaches, most of which were involved in the mitogen-activated protein kinase signaling pathway in plants, plant–pathogen interaction, plant hormone signal transduction, and the phenylpropanoid biosynthesis pathway. In particular, the DEGs related to phenylpropanoid metabolism, such as peroxidase, flavonoid, and isoflavonoid biosynthesis were significantly downregulated. Nontargeted metabolomic analysis revealed 44 differential metabolites, 9 of which were increased and 35 of which were decreased in the NAG-treated fruit. The decreased metabolites were secondary metabolites, including polyphenols, flavonoids, terpenoids, and glycosides. The relationship between HXK and phenylpropanoid metabolism was further investigated, and we found that in HXK-inhibited fruits the activities of phenylalanine ammonia-lyase, 4-coumarate-CoA ligase, and cinnamate 4-hydroxylase were significantly decreased over the control fruit, as well as the total phenol and total flavone contents were also significantly decreased. These results demonstrate that the inhibition of HXK activity decreases the disease resistance of peach fruits by affecting sugar metabolism and the phenylpropanoid pathway.

ABA spray on Arabidopsis seedlings increases mature plants vigor under optimal and water‐deficit conditions partly by enhancing nitrogen assimilation

“…Furthermore, there is evidence that GlcN induces HXK-mediated induction of oxidative stress, leading to growth repression in Arabidopsis (Ju et al, 2009), and accordingly, scavenging of endogenous GlcN enhanced tolerance to oxidative, water-deficit, and cold stress (Chu et al, 2010). In the HXK-inhibited fruits, the sucrose content was higher and the glucose and fructose contents were lower than those in the control fruits (Han et al, 2022). Thus, it is conceivable to hypothesize that in our experiments, water spray resulted in increased levels of glucosamine, which inhibited HXK leading to decreased flux through glycolysis and TCA, thus, sucrose accumulated and hexoses were depleted.…”

Hexokinase1: A glucose sensor involved in drought stress response and sugar metabolism depending on its kinase activity in strawberry

“…The WT strawberry plants were treated with 20% PEG-6000, in the presence or absence of N-acetylglucosamine (NAG), a known hexokinase inhibitor which was commonly used to investigate the role of plant hexokinases (Han et al, 2022;. After 12 hours, the plants began to show obvious wilting.…”

“…While NbHXK1 in tobacco, which governs the cell programmed death in the tobacco leaves, promotes plants' resistance to the methyl viologen-induced oxidative stress and pathogen infection (Sarowa et al, 2008). Inhibition of HXK by NAG decreased the phenylpropanoid metabolic pathway and resistance to Brown Rot has been documented in peach fruits (Han et al, 2022). Through the NAG inhibition experiments, it is evident that the antioxidant enzyme system, stress-induced ABA accumulation, and the selected typical drought responsive genes were all directly affected (Figure 7), indicating that the hexokinase activity of HXKs were indispensable for strawberry's stress response (summarized in Figure 9).…”

Combined analysis of mRNA and miRNA transcriptomes reveals the regulatory mechanism of Xanthomonas arboricola pv pruni resistance in Prunus persica

“…Svetaz et al discussed the pathogenicity and plant response mechanism of resistant and susceptible peach varieties to amoeba fungi, and revealed the commonness and difference of peach trees in the process of infection and early events [ 8 ].Recent studies have shown that some genes are involved in resistance to bacterial wilt [ 9 ]. The transcriptome of Monilinia fructicola during different stages of peach brown rot infection has been studied in several research articles [ 10 , 11 ]. Research related to plant disease resistance provides a detailed picture of how gene expression is regulated under specific pathogen infections, which helps to deepen our understanding of the molecular mechanisms underlying the interactions between plants and pathogens [ 12 – 15 ].…”