Hydrogen-rich water treatment increased several phytohormones and prolonged the shelf life in postharvest okras

Abstract

Hydrogen-rich water (HRW) treatment has been reported to delay the softening and senescence of postharvest okras, but its regulatory mechanism remains unclear. In this paper, we investigated the effects of HRW treatment on the metabolism of several phytohormones in postharvest okras, which act as regulatory molecules in fruit ripening and senescence processes. The results showed that HRW treatment delayed okra senescence and maintained fruit quality during storage. The treatment upregulated all of the melatonin biosynthetic genes such as AeTDC, AeSNAT, AeCOMT and AeT5H, contributing to the higher melatonin content in the treated okras. Meanwhile, increased transcripts of anabolic genes but lower expression of catabolic genes involved in indoleacetic acid (IAA) and gibberellin (GA) metabolism were observed in okras when treated with HRW, which was related to the enhanced levels of IAA and GA. However, the treated okras experienced lower abscisic acid (ABA) content as compared to the non-treated fruit due to the down-regulation of its biosynthetic genes and up-regulation of the degradative gene AeCYP707A. Additionally, there was no difference in γ-aminobutyric acid between the non-treated and HRW-treated okras. Collectively, our results indicated that HRW treatment increased levels of melatonin, GA and IAA, but decreased ABA content, which ultimately delayed fruit senescence and prolonged shelf life in postharvest okras.

Melatonin delayed senescence by modulating the contents of plant signalling molecules in postharvest okras

“…It has been reported that the treatment with exogenous melatonin induced the expression of melatonin biosynthetic genes, thus increasing the levels of endogenous melatonin in postharvest horticultural products ( Cao et al., 2016 ; Hu et al., 2017 ). Our recent study also found the hydrogen rich water delayed senescence in okras after harvest via upregulating the expression of melatonin synthesis-related genes and endogenous melatonin content ( Dong et al., 2023 ). Therefore, the data presented here clearly showed that suspension of senescence in okras treated with melatonin could be due to the upregulation of melatonin biosynthetic genes and the resultant increase in endogenous melatonin content.…”

“…The visual evaluation of senescence index on the surface of ten okras from each replicate was conducted. Senescence was rated according to methods described by Dong et al. (2023) .…”

“…Total RNA was extracted and subjected to reverse transcription using the methodology described by Dong et al. (2023) .…”

“…To our understanding, however, there was a lack of literature on the influence of melatonin, an essential signalling molecule, on other phytohormones with respect to senescence process in postharvest okras. Our previous study has demonstrated that a correlation between the presence of phytohormones, including indole-3-acetic acid (IAA), ABA, and gibberellin (GA), and the senescence process in postharvest okras ( Dong et al., 2023 ). Therefore, the purpose of the current investigation was to evaluate the regulation of melatonin on endogenous plant signalling molecules in relation to the senescence retardation and storage life extension in harvested okras by examining the levels of IAA, GABA, ABA and GA and their metabolizing genes.…”

Enhancement of Growth and Secondary Metabolites by the Combined Treatment of Trace Elements and Hydrogen Water in Wheat Sprouts

“…It has been suggested that agriculture techniques should use hydrogen as a treatment for plants [11]. According to the study, hydrogen-rich water enhanced many phytohormones and extended the shelf life of postharvest okras, showing that it has the potential to improve fruit quality [12]. One study found that hydrogen plays a role in enhancing the activity of antioxidant enzymes and the transcription of related genes, which can promote the growth of mung bean and rice seedlings and roots [13].…”