Nitric oxide induced thermotolerance in strawberry plants by activation of antioxidant systems and transcriptional regulation of heat shock proteins

Abstract

ABSTRACT An experiment was conducted to examine whether application of sodium nitroprusside (SNP), a donor of NO, can improve thermo-tolerance of strawberry (Fragaria × ananassa) plants through inducing antioxidant system, and up-regulating heat stress transcription factors (HSFs) and heat shock proteins (HSPs) genes. Ventana strawberry plants were exposed to various temperatures (25, 35, and 40°C) for 24 h after pre-treatment with 0, 50, and 100 μM SNP. Heat stress significantly induced malondialdehyde and hydrogen peroxide (H2O2) contents, and increased accumulation of proline, whereas reduced relative water content (RWC), leaf chlorophyll fluorescence, and carotenoid content. In addition, heat stress enhanced superoxide dismutase and guaiacol peroxidase activities, increased glutathione and ascorbic acid contents, and reduced catalase and ascorbate peroxidase activities. Pre-treatment with SNP, especially at 100 μM, ameliorated heat injury by controlling the overaccumulation of H2O2, reducing lipid peroxidation, improvement of RWC, and increasing the enzymatic and non-enzymatic antioxidants. Transcriptomic profiling analysis showed that the expression of FaTHSFA2a, FaTHSFB1a, HSP70, and HSP90 in SNP pre-treated plants was significantly higher than non-treated plants after 2 h of heat stress at 40°C. These results suggested that NO alleviates heat-induced oxidative damage by modulating antioxidant pathways and fast inducing the expression of heat-stress related genes.