Melon pest management relies on the excessive application of pesticides. Reducing pesticide spraying has become a global issue for environmental sustainability and human health. Therefore, developing a new cropping system that is sustainable and eco-friendly is important. This study found that melon seedlings irrigated with ultrafine water containing H2 and O2 (UFW) produced more root hairs, increased shoot height, and produced more flowers than the control irrigated with reverse osmosis (RO) water. Surprisingly, we also discovered that UFW irrigation significantly reduced aphid infestation in melon. Based on cryo-scanning electron microscope (cryo-SEM) observations, UFW treatment enhanced trichome development and prevented aphid infestation. To investigate whether it was H2 or O2 that helped to deter insect infestation, we prepared UF water enrichment of H2 (UF+H2) and O2 (UF+O2) separately and irrigated melons. Cryo-SEM results indicated that both UF+H2 and UF+O2 can increase the density of trichomes in melon leaves and petioles. RT-qPCR showed that UF+H2 significantly increased the gene expression level of the trichome-related gene GLABRA2 (GL2). We planted melons in a plastic greenhouse and irrigated them with ultrafine water enrichment of hydrogen (UF+H2) and oxygen (UF+O2). The SPAD value, photosynthetic parameters, root weight, fruit weight, and fruit sweetness were all better than the control without ultrafine water irrigation. UFW significantly increased trichome development, enhanced insect resistance, and improved fruit traits. This system thus provides useful water management for pest control and sustainable agricultural production.

The effects of methyl jasmonate (MeJ) on growth and taxoid formation in the cell culture of Himalayan yew was investigated for elucidate the specifics of the action of phytohormones on dedifferentiated plant cells in vitro. The characteristics of the same suspension culture of Taxus wallichiana was compared in 2017 ("young culture") and in 2022 ("old culture") - 1.5 or 6 years after culture induction, respectively. Cells were grown in flasks and bioreactors, MeJ (100 µM) was added at the exponential growth phase. It was found that cell culture demonstrated good growth (dry weight (DW) accumulation 10–18 g/l, specific growth rate µ = 0.15–0.35 day-1) regardless of "age", cultivation system and MeJ addition. UPLC–ESI-MS analysis showed the presence of C14-hydroxylated taxoids (yunnanxane, taxuyunnanine C, sinenxane C, sinenxane B) in cell biomass in the amounts comparable to plants. The content of C14-OH taxoids during 5 years of cultivation increased by 3-5 times. It was 0.2–1.6 mg/g DW for "young culture” and 0.6-10.1 mg/g for “old culture” depending on cultivation conditions. The ratio of individual compounds changed also: in the "young culture" was predominant yunnanxane, in the "old culture" - sinenxane C. Important that C13-hydroxylated taxoids were found in trace amounts only in the "young culture” (below 0.05 mg/g DW) and were not detected in the "old culture”. The response to MeJ was radically different depending on culture’s «age». In the “young culture”, exogenous MeJ had no effect on the content of C14-OH com-pounds, but significantly (almost 10 times) increased the content of C13-OH compounds. In particular, paclitaxel concentration was elevated up to 0.12–0.19 mg/g DW, which is comparable to its content in the bark of yew trees. By contrast, MeJ added to the "old culture” had minor effect on the synthesis of C13-OH toxoids that appeared in trace amounts only (below 3.5 µg/g DW for paclitaxel) but notably increased the content of C14-OH compounds (1.5–2.0 times in flasks and 5–8 times in bioreactors). These findings suggest that hormonal signaling in dedifferentiated yew cells grown in vitro is different from that in plants and change with culture age. This might be a result of the high level of heterogeneity of cells in vitro and their constant auto-selection for proliferate intensity which leads to predominant formation of C14-OH taxoids versus C13-OH taxoids and modified cell response to exogenous MeJ treatment. These results have both fundamental and practical biotechnological application.

Application of exogenous jasmonate can stimulate the production of ethylene, carotenoids and aroma compounds, resulting in the acceleration of fruit ripening. These alterations improve fruit quality and make fruit desirable for human consumption, but overripening of a fruit results in large losses of fruit crops. In order to overcome this problem, 1-methylcyclopropene was ap-plied to the fruits due to its capacity to block the receptors of ethylene, resulting in the sup-pressed of fruit ripening. In this study, treatments only with 1-methylcyclopropene, and with both 1-methylcyclopropene and methyl jasmonate was conducted to observe if an exogenous methyl jasmonate can improve the levels of metabolites in their fruits with ethylene receptors blocked. Fruits were analyzed at 4, 10 and 21 day after harvest (DAH) and compared with the no treated fruits. The postharvest treatments affected primary metabolites (sugars, organic acids, amino acids and fatty acids) and secondary metabolites (carotenoids, tocopherols and phytoster-ols). However, the lipid metabolism of the tomato was the most impacted by the exogenous jasmonate. Fatty acids, carotenoids, tocopherols and phytosterols showed a delay in their pro-duction at 4 and 10 DAH. In contrast, at 21 DAH these non-polar metabolites exhibited an im-portant improvement in their accumulation.

Sporisorium scitamineum, the basidiomycetous fungus causing sugarcane smut that leads to severe losses in sugarcane quantity and quality, undergoes sexual mating to form dikaryotic hyphae capable of invading the host cane. Therefore, suppressing dikaryotic hyphae formation would potentially be an effective way to prevent host infection by the smut fungus, and the following disease symptom development. The phytohormone methyl jasmonate (MeJA) has been showed to induce plant defense against insects and microbial pathogens. In this study, we verified that exogenous addition of MeJA suppressed dikaryotic hyphae formation under in vitro culture condition, and effective in inhibiting maize smut disease symptom caused by Ustilago maydis. We constructed an Escherichia coli strain expressing plant JMT gene, encoding a jasmonic acid carboxyl methyl transferase that catalyzes conversion from jasmonic acid (JA) to MeJA. By GC-MS we confirmed that the transformed E. coli strain, designated as pJMT strain, was able to produce MeJA in the presence of JA and S-adenosylmethionine (SAM; as methyl donor). Furthermore, the pJMT strain was able to suppress S. scitamineum filamentous growth under in vitro culture condition. It waits to further optimize JMT expression under field condition, in order to utilize the pJMT strain as a biocontrol agent (BCA) of sugarcane smut disease. Overall, our study provides a potentially novel method for controlling crop fungal diseases by boosting phytohormone biosynthesis.