Gas Chromatography-Mass Spectrometry Metabolite Analysis Combined with Transcriptomic and Proteomic Provide New Insights into Revealing Cuticle Formation during Pepper Development

Effects and mechanisms of proanthocyanidins-derived carbon dots on alleviating salt stress in rice by muti-omics analysis

Carbon dots (CDs) with different structures were prepared by electrolysis (PE-CDs) and hydrothermal (PH-CDs) methods using proanthocyanidins as precursors. The smaller size and lower zeta potential enabled the PE-CDs treated rice seedlings to exhibit greater resistance to salt stress. The fresh weight of rice seedlings under salt stress was significantly increased by spraying CDs every other day for two weeks. PE-CDs treated group exhibited a faster electron transport rate, and the SOD activity and flavonoid content were 2.5-fold and 0.23-fold higher than those of the salt stress-treated group. Furthermore, the metabolomics and transcriptomics analysis revealed that the PsaC gene of photosystem I was significantly up-regulated under PE-CDs treatment, which accelerated electron transfer in photosystem I. The up-regulation of BX1 and IGL genes encoding indole synthesis allowed rice to enhance stress tolerance through tryptophan and benzoxazine biosynthesis pathways. These findings offer help in purposefully synthesizing CDs and boosting food production.

1-MCP treatment improves the postharvest quality of Jinxiu yellow peach by regulating cuticular wax composition and gene expression during cold storage

This study aimed to analyze the effect of 1-methylcyclopropene (1-MCP) treatment on the postharvest quality, epidermal wax morphology, composition, and gene expression of Jinxiu yellow peach during cold storage. The results showed that 1-MCP treatment could maintain the postharvest quality of peach fruit as compared to control (CK) during cold storage. The wax crystals of peach fruit were better retained by 1-MCP, and they still existed in 0.6 and 0.9 µL/L 1-MCP treated fruit at 36 days. The total wax content in all the fruit increased first and then decreased during cold storage. Meanwhile, n-alkanes and primary alcohols were the main wax components. Compared to CK, 1-MCP treatment could delay the reduction of wax content during cold storage. The correlation analysis indicated that the postharvest quality of yellow peach was mainly affected by the contents of fatty acids and triterpenoids in cuticular wax. The transcriptomics results revealed PpaCER1, PpaKCS, PpaKCR1, PpaCYP86B1, PpaFAR, PpaSS2, and PpaSQE1 played the important roles in the formation of peach fruit wax. 1-MCP treatment upregulated PpaCER1 (18785414, 18786441, and 18787644), PpaKCS (18774919, 18789438, and 18793503), PpaKCR1 (18790432), and PpaCYP86B1 (18789815) to deposit more n-alkanes and fatty acids during cold storage. This study could provide a new perspective for regulating the postharvest quality of yellow peach in view of the application of cuticular wax. PRACTICAL APPLICATION: 'Jinxiu' yellow peach fruit is favorable among consumers because of its high commercial value. However, it ripens and deteriorates rapidly during storage, leading to serious economic loss and consumer disappointment. The effect of 1-methylcyclopropene (1-MCP) treatment on the postharvest quality, epidermal wax morphology, composition, and genes regulation of 'Jinxiu' yellow peach during cold storage was assessed. Compared to control, 1-MCP treatment could retain the storage quality of yellow peach by affecting cuticular wax composition and gene expression. This study could provide new perspective for regulating the postharvest quality of yellow peach in view of the application of cuticular wax.

Effects of artificial sweetener acesulfame on soil-dwelling earthworms (Eisenia fetida) and its gut microbiota

Artificial sweeteners (AS) are the emerging contaminants with potential toxicity to living organisms. The effects of AS to soil typical invertebrates have not been revealed. In this study, the responses of earthworms (Eisenia fetida) and gut microbial communities to acesulfame-contaminated soils (0.1, 1 and 10 mg kg-1) were studied using transcriptomics, metabolomics and metagenomics analyses. The fresh weight of earthworms was significantly stimulated by acesulfame at concentrations of 1 mg kg-1. Sphingolipid metabolism, purine metabolism, cutin, suberine and wax biosynthesis pathways were significantly affected. At 10 mg kg-1 treatment, the amount and weight of cocoons were significantly increased and decreased, respectively, accompanied by the significant disorder of ECM-receptor interaction, and carbon fixation in photosynthetic organisms pathways. Lysosome pathway was significantly affected in all the treatments. Moreover, the acesulfame significantly increased the relative abundance of Bacteroidetes and Mucoromycota, and decreased Proteobacteria in the gut of earthworms. Our multi-level investigation indicated that AS at a relatively low concentration induced toxicity to earthworms and AS pollution has significant environmental risks for soil fauna.

Composition, metabolism and postharvest function and regulation of fruit cuticle: A review

The cuticle of plants, a hydrophobic membrane that covers their aerial organs, is crucial to their ability to withstand biotic and abiotic stressors. Fruit is the reproductive organ of plants, and an important dietary source that can offer a variety of nutrients for the human body, and fruit cuticle performs a crucial protective role in fruit development and postharvest quality. This review discusses the universality and diversity of the fruit cuticle composition, and systematically summarizes the metabolic process of fruit cuticle, including the biosynthesis, transport and regulatory factors (including transcription factors, phytohormones and environmental elements) of fruit cuticle. Additionally, we emphasize the postharvest functions and postharvest regulatory technologies of fruit cuticle, and propose future research directions for fruit cuticle.

Fine mapping and candidate gene analysis of CaFCD1 affecting cuticle biosynthesis in Capsicum annuum L

CaFCD1 gene regulates pepper cuticle biosynthesis. Pepper (Capsicum annuum L.) is an economically important vegetable crop that easily loses water after harvesting, which seriously affects the quality of its product. The cuticle is the lipid water-retaining layer on the outside of the fruit epidermis, which regulates the biological properties and reduces the rate of water-loss. However, the key genes involved in pepper fruit cuticle development are poorly understood. In this study, a pepper fruit cuticle development mutant fcd1 (fruit cuticle deficiency 1) was obtained by ethyl methanesulfonate mutagenesis. The mutant has great defects in fruit cuticle development, and the fruit water-loss rate of fcd1is significantly higher than that of the wild-type '8214' line. Genetic analysis suggested that the phenotype of the mutant fcd1 cuticle development defect was controlled by a recessive candidate gene CaFCD1 (Capsicum annuum fruit cuticle deficiency 1) on chromosome 12, which is mainly transcribed during fruit development. In fcd1, a base substitution within the CaFCD1 domain resulted in the premature termination of transcription, which affected cutin and wax biosynthesis in pepper fruit, as revealed by the GC-MS and RNA-seq analysis. Furthermore, the yeast one-hybrid and dual-luciferase reporter assays verified that the cutin synthesis protein CaCD2 was directly bound to the promoter of CaFCD1, suggesting that CaFCD1 may be a hub node in the cutin and wax biosynthetic regulatory network in pepper. This study provides a reference for candidate genes of cuticle synthesis and lays a foundation for breeding excellent pepper varieties.