Transcriptomic and metabolomic profiling reveal the mechanism underlying the inhibition of wound healing by ascorbic acid in fresh-cut potato.

Ascorbic acid (AsA) inhibits wound healing in fresh-cut potatoes (FCP); however, the comprehensive regulatory mechanisms of the chemical during wound healing remain unclear. Here, physiobiochemical, transcriptomic, and metabolomic analyses were performed. In total, 685 differentially expressed genes (DEGs) and 1921 differentially accumulated metabolites (DAMs) were identified between control and AsA-treated samples. The level of the majority of DEGs expression and DAMs abundance in AsA-treated samples were similar to data of newly cut samples. The collective data indicated that the AsA treatment inhibited wound healing in FCPs by regulating glutathione metabolism, enhancing starch metabolism, and inhibiting phenylalanine metabolism, sucrose degradation, and fatty acid synthesis. Major genes and metabolites affected by AsA treatment included StGST, StPAL, StPHO1 and StLOX5, and starch, sucrose, and linoleic acid. AsA treatment increased starch content and amylase and lipoxygenase activity and decreased free fatty acid level. Our research provides fundamental insights into wound healing mechanisms in FCP.

Inactivation of BoORP3a, an oxysterol-binding protein, causes a low wax phenotype in ornamental kale.

Identifying genes associated with wax deposition may contribute to the genetic improvement of ornamental kale. Here, we characterized a candidate gene for wax contents, BoORP3a, encoding an oxysterol-binding protein. We sequenced the BoORP3a gene and coding sequence from the high-wax line S0835 and the low-wax line F0819, which revealed 12 single nucleotide polymorphisms between the two lines, of which six caused five amino acids substitutions. BoORP3a appeared to be relatively well conserved in Brassicaceae, as determined by a phylogenetic analysis, and localized to the endoplasmic reticulum and the nucleus. To confirm the role of BoORP3a in wax deposition, we generated three orp3a mutants in a high-wax kale background via CRISPR/Cas9-mediated genome editing. Importantly, all three mutants exhibited lower wax contents and glossy leaves. Overall, these data suggest that BoORP3a may participate in cuticular wax deposition in ornamental kale.

Transcriptome Analysis of Green and White Leaf Ornamental Kale Reveals Coloration-Related Genes and Pathways.

Leaf color is a crucial agronomic trait in ornamental kale. However, the molecular mechanism regulating leaf pigmentation patterns in green and white ornamental kale is not completely understood. To address this, we performed transcriptome and pigment content analyses of green and white kale leaf tissues. A total of 5,404 and 3,605 different expressed genes (DEGs) were identified in the green vs. white leaf and the green margin vs. white center samples. Kyoto Encyclopedia of Genes and Genome (KEGG) pathway enrichment analysis showed that 24 and 15 common DEGs in two pairwise comparisons were involved in chlorophyll metabolism and carotenoid biosynthesis, respectively. Seventeen genes related to chlorophyll biosynthesis were significantly upregulated in green leaf tissue, especially chlH and por. Of the 15 carotenoid biosynthesis genes, all except CYP707A and BG1 were lower expressed in white leaf tissue. Green leaf tissue exhibited higher levels of chlorophyll and carotenoids than white leaf tissue. In addition, the DEGs involved in photosystem and chlorophyll-binding proteins had higher expression in green leaf tissue. The PSBQ, LHCB1.3, LHCB2.4, and HSP70 may be key genes of photosynthesis and chloroplast formation. These results demonstrated that green and white coloration in ornamental kale leaves was caused by the combined effects of chlorophyll and carotenoid biosynthesis, chloroplast development, as well as photosynthesis. These findings enhance our understanding of the molecular mechanisms underlying leaf color development in ornamental kale.

A single-base insertion in BoDFR1 results in loss of anthocyanins in green-leaved ornamental kale.

KEY MESSAGE: A CRISPR/Cas9-based knockout assay verified that BoDFR1 drives anthocyanin accumulation in ornamental kale and that BoDFR2, an ortholog of BoDFR1, is redundant. Anthocyanins are widely distributed in nature and give plants their brilliant colors. Leaf color is an important trait for ornamental kale. In this study, we measured anthocyanin contents and performed transcriptome deep sequencing (RNA-seq) of leaves from pink and green ornamental kale. We observed substantial differences in the expression levels of the two DIHYDROFLAVONOL 4-REDUCTASE-encoding genes BoDFR1 (Bo9g058630) and its ortholog BoDFR2 (Bo2g116380) between green-leaved and pink-leaved kale by RNA-seq and RT-qPCR. We cloned and sequenced BoDFR1 and BoDFR2 from both types of kale. We identified a 1-bp insertion in BoDFR1 and a 2-bp insertion in BoDFR2 in green-leaved kale compared to the sequences obtained from pink-leaved kale, both mapping to the second exon of their corresponding gene and leading to premature termination of translation. To confirm the genetic basis of the absence of anthocyanins in green kale, we used CRISPR/Cas9 genome editing to separately knock out BoDFR1 or BoDFR2 in the pink-leaved ornamental kale inbred line P23. We detected very low accumulation of anthocyanins in the resulting mutants Bodfr1-1 and Bodfr1-2, while Bodfr2-1 and Bodfr2-2 had anthocyanin levels comparable to those of the wild-type. We conclude that the insertion in BoDFR1, rather than that in BoDFR2, underlies the lack of anthocyanins in green-leaved ornamental kale. This work provides insight into the function of DFR and will contribute to germplasm improvement of ornamental plants.

The Garbage Enzyme with Chinese Hoenylocust Fruits Showed Better Properties and Application than When Using the Garbage Enzyme Alone.

Garbage enzyme (GE) is a vinegar or alcohol product derived from fermenting fresh kitchen waste, such as vegetable and fruit residues (peels, cuttings and bits), sugar (brown sugar, jaggery or molasses sugar) and water. Chinese honeylocust fruits (Gleditsia sinensis) have been used in China for at least 2000 years as a detergent. The aim of the study was to investigate the properties and application of Chinese honeylocust garbage enzyme (CHGE), which is produced when equal amounts of Chinese honeylocust fruits and fresh wastes are mixed. The results showed that CHGE had lesser microbial communities and lower surface tension than GE. CHGE also had higher viscosity, foam stability and emulsion stability than GE. Compared with GE, CHGE induced higher enzymatic amylase, cellulase, lipase and protease activities. CHGE had stronger detergency than GE and a 100× dilution of CHGE could significantly remove pesticide residues after a 30 min soaking treatment. The study showed that as a biological detergent, CHGE is safer and more environmentally friendly than GE and has remarkable washing and cleaning power. The preparation method of the detergent is simple: it can be prepared at home using fruit and vegetable waste, which is beneficial to the secondary utilization of waste and the reduction of pollution to the environment and damage to human health.

Simultaneous changes in anthocyanin, chlorophyll, and carotenoid contents produce green variegation in pink-leaved ornamental kale.

BACKGROUND: Anthocyanin, chlorophyll, and carotenoid pigments are widely distributed in plants, producing various colors. Ornamental kale (Brassica oleracea var. acephala DC) which has colorful inner leaves is an ideal plant to explore how these three pigments contribute to leaf color. The molecular mechanisms of the coloration in ornamental kale could provide reference for exploring the mechanisms of pigmentation in other plants. RESULTS: In this study, we sequenced the transcriptome and determined the pigment contents of an unusual cultivar of ornamental kale with three different types of leaf coloration: pink (C3), light pink (C2), and variegated pink-green (C1). A total of 23,965 differentially expressed genes were detected in pairwise comparisons among the three types of leaves. The results indicate that Bo9g058630 coding dihydroflavonol 4-reductase (DFR) and Bo3g019080 coding shikimate O-hydroxycinnamoyltransferase (HCT) acted in anthocyanin biosynthesis in pink leaves. Bo1g053420 coding pheophorbidase (PPD) and Bo3g012430 coding 15-cis-phytoene synthase (crtB) were identified as candidate genes for chlorophyll metabolism and carotenoid biosynthesis, respectively. The transcription factors TT8, MYBL2, GATA21, GLK2, and RR1 might participate in triggering the leaf color change in ornamental kale. Anthocyanin content was highest in C3 and lowest in C1. Chlorophyll and carotenoid contents were lowest in C2 and highest in C1. CONCLUSIONS: Based on these findings, we suspected that the decrease in anthocyanin biosynthesis and the increase in chlorophyll and carotenoid biosynthesis might be the reason for the leaf changing from pink to variegate pink-green in this unusual cultivar. Our research provides insight into the molecular mechanisms of leaf coloration in ornamental kale, contributing to a theoretical foundation for breeding new varieties.

Integrated Analysis of Transcriptomic and Metabolomic Data Reveals the Mechanism by Which LED Light Irradiation Extends the Postharvest Quality of Pak-choi (Brassica campestris L. ssp. chinensis (L.) Makino var. communis Tsen et Lee).

Low-intensity (10 µmol m-2 s-1) white LED (light-emitting diode) light effectively delayed senescence and maintained the quality of postharvest pakchoi during storage at 20 °C. To investigate the mechanism of LED treatment in maintaining the quality of pakchoi, metabolite profiles reported previously were complemented by transcriptomic profiling to provide greater information. A total of 7761 differentially expressed genes (DEGs) were identified in response to the LED irradiation of pak-choi during postharvest storage. Several pathways were markedly induced by LED irradiation, with photosynthesis being the most notable. More specifically, porphyrin and chlorophyll metabolism and glucosinolate biosynthesis were significantly induced by LED irradiation, which is consistent with metabolomics reported previously. Additionally, chlorophyllide a, chlorophyll, as well as total glucosinolate content was positively induced by LED irradiation. Overall, LED irradiation delayed the senescence of postharvest pak-choi mainly by activating photosynthesis, inducting glucosinolate biosynthesis, and inhibiting the down-regulation of porphyrin and chlorophyll metabolism pathways. The present study provides new insights into the effect and the underlying mechanism of LED irradiation on delaying the senescence of pak-choi. LED irradiation represents a useful approach for extending the shelf life of pak-choi.

An untargeted metabolomic approach reveals significant postharvest alterations in vitamin metabolism in response to LED irradiation in pak-choi (Brassica campestris L. ssp. chinensis (L.) Makino var. communis Tsen et Lee).

The main objective of this study was to investigate the effect of low-level light emitting diode (LED) irradiation on the metabolite profile of pak-choi. A total of 633 different molecular features (MFs) were identified among sample groups (initial, dark-treated, light-treated) using an untargeted metabolomic approach. The identified metabolites were associated with 24 different metabolic pathways. Four of the pathways including carbon pool by folate, folate biosynthesis, thiamine metabolism, and glutathione metabolism, all of which are associated with vitamin biosynthesis, changed significantly. Metabolites in four of the pathways exhibited significant differences from the control in response to LED irradiation. Additionally, porphyrin and chlorophyll metabolism, as well as glucosinolate biosynthesis, riboflavin metabolism, and carotenoid biosynthesis were positively induced by LED irradiation. These results indicate that postharvest LED illumination represents a potential tool for modifying the metabolic profile of pak-choi to maintain quality and nutritional levels.