Ampa Kongsuwan

The ability of salicylic acid (SA) to control post-harvest fungal disease mango anthracnose caused by plant pathogen Colletotrichum gloeosporioides and the accompanying biochemical and metabolomic changes were studied. In vitro, C. gloeosporioides mycelial growth at 25 °C for 7 days was inhibited by SA at 2 and 5 mM concentrations. In vivo, mango fruits were treated with 2 mM SA for 10 min, then inoculated with C. gloeosporioides. The fruits were then stored at 25 °C and sampled every 2 days after inoculation. The anthracnose severity, infection index, malondialdehyde (MDA), antioxidant capacity (DPPH and FRAP), total phenolics (TPC), total flavonoids (TFC), ascorbic acid, and metabolomic changes in the peel were studied. Six days post inoculation, the SA-treated fruits showed reduced anthracnose severity, and the infection index was significantly reduced by SA (57%) compared to the control (67%). The SA-treated fruits exhibited decreased MDA, enhanced antioxidant capacity, and increased levels of TPC, TFC, and vitamin C in the peel. Compared with the control, SA treatment reduced MDA content by approximately 50% and increased TPC, TFC, and FRAP antioxidant capacity by 77%, 31%, and 29%, respectively. Vitamin C content and DPPH antioxidant activity were also significantly higher in SA-treated fruits. Untargeted metabolomics and a principal component analysis revealed a separation group between the SA-treated and control fruit. The SA treatment induced D-amino acids, phenylalanine pathways, and the biosynthesis of secondary metabolites such as phenolic acid. Together, these findings demonstrate that SA enhances mangoes’ resistance to post-harvest anthracnose through direct antifungal action and the activation of host defense by improving the antioxidant systems and stimulating the accumulation of secondary defense metabolites in mango fruit.

Background and Aims: Color, a key determinant of grape berry quality, is influenced by light, temperature, and plant hormones during development. We investigated the effects of red‐, blue‐, and combined red‐and‐blue‐light irradiations on photoreceptors, abscisic acid (ABA) signaling, and anthocyanin biosynthesis in order to clarify their mutual relationships. Methods and Results: The experiment was conducted over two consecutive years (2023–2024) using the same nine “Kyoho” grapevines, which were eight years old at the start of the study. In 2023, treatments consisted of irradiating grape clusters with either red‐light‐emitting diodes (LEDs) or blue LEDs. In 2024, the treatments were modified to irradiation with blue LEDs or a combination of red and blue LEDs. Compared to an untreated control group, the irradiation of grape clusters with red or blue LEDs at 240 μmol m ⁻² s ⁻¹ both significantly increased the expressions of the photoreceptor genes VvPHYa (phytochromes) , VvPHYb , VvCRYa (cryptochromes), and VvPHOT2 (phototropins), those of genes VvSnRK2.6 (an SNF 1‐related protein kinase) and VvABF2 (an ABA‐responsive element‐binding transcription factor) involved in the activation of ABA signaling, and those of genes VvMYBa1 and VvUFGT involved in anthocyanin synthesis, as well as anthocyanin synthesis. The expression of VvPP2C9 (protein phosphatase 2C9), which is negatively related to ABA signaling, was decreased. There were no significant differences in these factors between the red‐ and blue‐irradiated sections. The combined treatment with red and blue light, as well as blue‐light exposure alone, upregulated photoreceptor genes’ expression, ABA signaling, anthocyanin synthesis enzyme genes’ expression, and anthocyanin synthesis compared to the untreated control, whereas no difference was observed between the combined treatment and the blue‐light treatment. Conclusions: These results suggest that both red‐ and blue‐light exposure stimulate ABA signaling in grape skins and that the activation of either the red‐ or blue‐light receptors promotes anthocyanin synthesis.