Transcriptomic and Metabolic Analyses Reveal the Mechanism of Ethylene Production in Stony Hard Peach Fruit during Cold Storage

Abstract

Stony hard (SH) peach (Prunus persica L. Batsch) fruit does not release ethylene and has very firm and crisp flesh at ripening, both on- and off-tree. Long-term cold storage can induce ethylene production and a serious risk of chilling injury in SH peach fruit; however, the regulatory mechanism underlying ethylene production in stony hard peach is relatively unclear. In this study, we analyzed the phytohormone levels, fruit firmness, transcriptome, and lipidome changes in SH peach ‘Zhongtao 9’ (CP9) during cold storage (4 °C). The expression level of the ethylene biosynthesis gene PpACS1 and the content of ethylene in SH peach fruit were found to be upregulated during cold storage. A peak in ABA release was observed before the release of ethylene and the genes involved in ABA biosynthesis and degradation, such as zeaxanthin epoxidase (ZEP) and 8’-hydroxylase (CYP707A) genes, were specifically induced in response to low temperatures. Fruit firmness decreased fairly slowly during the first 20 d of refrigeration, followed by a sharp decline. Furthermore, the expression level of genes encoding cell wall metabolic enzymes, such as polygalacturonase, pectin methylesterase, expansin, galactosidase, and β-galactosidase, were upregulated only upon refrigeration, as correlated with the decrease in fruit firmness. Lipids belonging to 23 sub-classes underwent differential rearrangement during cold storage, especially ceramide (Cer), monoglycosylceramide (CerG1), phosphatidic acid (PA), and diacyglyceride (DG), which may eventually lead to ethylene production. Exogenous PC treatment provoked a higher rate of ethylene production. We suspected that the abnormal metabolism of ABA and cell membrane lipids promotes the production of ethylene under low temperature conditions, causing the fruit to soften. In addition, ERF transcription factors also play an important role in regulating lipid, hormone, and cell wall metabolism during long-term cold storage. Overall, the results of this study give us a deeper understanding of the molecular mechanism of ethylene biosynthesis during the postharvest storage of SH peach fruit under low-temperature conditions.

Transcriptome analysis of harvested okra (Abelmoschus esculentus L.) in response to chilling stress

“…In addition, genes related to ETH and ABA biosynthesis and signaling were also found to be up-regulated during the cold storage period. Similar ndings were also reported in stony hard peach (Wang et al 2021) and jujube fruit (Kou et al 2019). Since the over-accumulation of ETH and ABA is detrimental to postharvest crops (Cocetta and Natalini 2022), these results also suggested that active measures should be taken to the metabolic mechanism of ETH and ABA in cold stored okra pods.…”

Peroxisomal Proteome Mining of Sweet Pepper (Capsicum annuum L.) Fruit Ripening Through Whole Isobaric Tags for Relative and Absolute Quantitation Analysis

“…Among them, it is worth highlighting the indoleacetic acid (IAA) amido hydrolase enzymes, responsible for controlling the levels of IAA in plant cells by converting auxin-amino acid conjugates into free IAA molecules ( Bartel and Fink, 1995 ; LeClere et al, 2002 ). Although it was thought that this was their only function, it has recently been shown that these proteins can regulate the expression of the enzyme 1-aminocyclopropane-1-carboxylic (ACC) synthase (ACS), altering the synthesis of ethylene during peach ripening ( Wang et al, 2021 ). This would imply a new point of interaction between auxin metabolism and ET, whose possible implications in pepper fruit ripening could be interesting to address in future research.…”

Molecular Insights into Freezing Stress in Peach Based on Multi-Omics and Biotechnology: An Overview

“…At temperatures ranging between 0 and 15 °C, the plants experience cold or freezing stress. In general, freezing/cold stress can impact the growth and development by suppressing the true genetic potential of a plant which subsequently affects the metabolic processes and enzyme activity and its related fluidity of plant cell membranes, resulting in material and metabolic transport disorders as well as chilling injury [ 13 , 14 ]. Additionally, cold and freezing stress persuade cold-induced osmotic stress where plants experience cellular dehydration due to inhibition in water intake due to low temperatures [ 15 ].…”