Hongdou Gao

The ratio of red to far-red (FR) light (the R/FR ratio) is a core signal regulating shade-induced internode elongation in plants, but the underlying mechanism in cucumber remains not fully elucidated. Therefore, in the present study, cucumber (Cucumis sativus L. ‘Zhongnong No. 26′) was used as the material, and through a combination of physiological, transcriptomic, and proteomic analyses, we investigated the mechanism underlying internode elongation via R/FR ratio in cucumber plants. Low R/FR ratio significantly promoted cucumber seedling internode elongation by enhancing the longitudinal growth of internode cells. Hormonal profiling decreased the contents of indole-3-acetic acid (IAA), salicylic acid (SA), cytokinin (CTK; tZR, T-zeatin, and iPR), and ethylene (Eth), whereas jasmonic acid (JA) and gibberellin (GA) contents were elevated in cucumber seedling internodes. Bioinformatics analysis revealed that low R/FR ratio upregulated GA biosynthesis-related genes (KAO, GA20ox), and the expression of genes/proteins encoding cell wall remodeling/biosynthesis enzymes (EXP, XTH and CesA), and aquaporin proteins (AQPs). Exogenous GA4/7 mimicked the promotive effect of low R/FR on internode elongation under white light, while the GA biosynthesis inhibitor paclobutrazol (PAC) reversed this response, confirming a central role for GA in this process. These results reveal the crucial role of cell wall biosynthesis and hormone metabolism-related genes/proteins in low R/FR ratio-induced cucumber internode elongation. Such work may further elucidate the evolutionary and agronomic trade-offs associated with shade avoidance and provide a basis for optimizing canopy architecture and light management in cucumber cultivation.

Tomato (Solanum lycopersicum L.) is a major economic vegetable crop globally, yet it is prone to gray mold disease caused by Botrytis cinerea infection during cultivation. Caffeoyl shikimate esterase (CSE) is a crucial component of the lignin biosynthesis pathway, which significantly contributes to plant stress resistance. Therefore, investigating the expression patterns of SlCSE after Botrytis cinerea infection may offer a theoretical foundation for breeding resistant tomato varieties. In this study, 11 SlCSE family members were identified from the tomato genome using bioinformatics analyses. Public transcriptome databases and RT-qPCR experiments were used to analyze gene expression in tomato tissues, responses to Botrytis cinerea infection, and the temporal characteristics of the response to 2-ethylfuran treatment during infection. These experiments resulted in the identification of the key gene SlCSE06. Transgenic tomato lines that overexpressed SlCSE06 were constructed to examine their resistance levels to gray mold disease. Many SlCSE genes were upregulated when tomato fruit were infected with Botrytis cinerea during the ripening stage. Furthermore, 24 h after treatment with 2-ethylfuran, most SlCSE genes exhibited increased expression levels compared with the control group, but they exhibited significantly lower levels at other time points. Thus, 2-ethylfuran treatment may enhance the responsiveness of SlCSEs. Based on this research, SlCSE06 was identified as the key gene involved in the response to Botrytis cinerea infection. The SlCSE06-overexpressing (OE6) tomato plants exhibited a 197.94% increase in expression levels compared to the wild type (WT). Furthermore, the lignin content in OE6 was significantly higher than in WT, suggesting that the overexpression of SlCSE06 enhanced lignin formation in tomato plants. At 5 days post-inoculation with Botrytis cinerea, the lesion diameter in OE6 decreased by 31.88% relative to the WT, whereas the lignin content increased by 370.90%. Furthermore, the expression level of SlCSE06 was significantly upregulated, showing a 17.08-fold increase compared with the WT. These findings suggest that 2-ethylfuran enhances the activation of the critical tomato disease resistance gene SlCSE06 in response to gray mold stress, thereby promoting lignin deposition to mitigate further infection by Botrytis cinerea.

The effect of palmitic acid (PA) on stem browning was investigated in freshly harvested mini-Chinese cabbage (Brassica pekinensis). Results indicated that concentrations of PA ranging from 0.03 g L⁻¹ to 0.05 g L⁻¹ inhibited stem browning and decreased the rate of respiration, electrolyte leakage, and weight loss, as well as the level of malondialdehyde (MDA) in freshly harvested mini-Chinese cabbage stored at 25 °C for 5 d. The PA treatment enhanced the activity of antioxidant enzymes (ascorbate peroxidase (APX), catalase (CAT), peroxidase (POD), 4-coumarate:CoA ligase (4CL) and phenylalamine ammonia lyase (PAL)), and inhibited the activity of polyphenol oxidase (PPO). The PA treatment also increased the level of several phenolics (chlorogenic acid, gallic acid, catechin, p-coumaric acid, ferulic acid, p-hydroxybenzoic acid, and cinnamic acid) and flavonoids (quercetin, luteolin, kaempferol, and isorhamnetin). In summary, results indicate that treatment of mini-Chinese cabbage with PA represents an effective method for delaying stem browning and maintaining the physiological quality of freshly harvested mini-Chinese cabbage due to the ability of PA to enhance antioxidant enzyme activity and the level of phenolics and flavonoids during 5 d.