Abstract
Nitric oxide (NO), a signaling molecule, participates in defense responses during plant–pathogen interactions. S-Nitrosoglutathione (GSNO) is found to be an active intracellular NO storage center and regulated by S-nitrosoglutathione reductase (GSNOR) in plants. However, the role of GSNOR in NO-induced disease resistance is not clear. In this research, the effects of NO and GSNOR inhibitor (N6022) on the defense response of harvested peach fruit to Monilinia fructicola infection were investigated. It was found that the disease incidence and lesion diameter of peach fruits were markedly (P < 0.05) reduced by NO and GSNOR inhibitor. However, the expression of GSNOR was significantly inhibited (P < 0.05) by NO only during 2–6 h. Analyses using iodo-TMT tags to detect the nitrosylation sites of GSNOR revealed that the sulfhydryl group of the 85-cysteine site was nitrosylated after NO treatment in peach fruit at 6 and 12 h, suggesting that exogenous NO enhances disease resistance via initial inhibition of gene expression and the S-nitrosylation of GSNOR, thereby inhibiting GSNOR activity. Moreover, NO and GSNOR inhibitor enhanced the expression of systemic acquired resistance (SAR)-related genes, such as pathogenesis-related gene 1 (PR1), nonexpressor of PR1 (NPR1), and TGACG-binding factor 1 (TGA1). These results demonstrated that S-nitrosylation of GSNOR protein and inhibition of GSNOR activity contributed to the enhanced disease resistance in fruit.
Highlights
Peach [Prunus persica (L.) Batsch] fruit is rich in nutrients that provide favorable growth conditions for pathogenic bacteria
Nitric oxide involves participating in plant responses to biotic and abiotic stresses as an important signaling molecule (Mur et al, 2006; Carreras and Poderoso, 2007)
Treatment of tomato fruit with L-arginine, a precursor of Nitric oxide (NO), inhibits the expansion of lesion diameter caused by B. cinerea (Zheng et al, 2011)
Summary
Peach [Prunus persica (L.) Batsch] fruit is rich in nutrients that provide favorable growth conditions for pathogenic bacteria. Due to the high temperature and environmental humidity during the picking period of the peach fruit, the infection and growth of pathogenic bacteria are accelerated, causing a large amount of decay of the peach fruit, resulting in huge economic losses. Brown rot caused by Monilinia fructicola is severely destructive to stone fruits, involving in cherries, plums, and peaches (Hu et al, 2011). Cold storage and chemical fungicides are widely used to inhibit brown rot development of peach fruit. Chemical fungicides can inhibit brown rot (Adaskaveg et al, 2005), but long-term use of chemicals may induce several problems such as fungicide resistance, chemicals residues on fruits, and environmental pollution. The development of safe and effective methods is necessary to control brown rot in stone fruit
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