Aug 2026· Horticulturae· Vol 12, pp. 1020· 0 citations· 57 references
TL;DR
JLAR1 plays a crucial role in PA biosynthesis in red walnut and is positively regulated by the transcription factor JrEGL1b, which improves the molecular regulatory network of pigment metabolism in red walnut and provide valuable molecular targets for the quality improvement and directional breeding of walnuts.
Abstract
The characteristic red walnut germplasm ‘RW-1′ (Juglans regia L.) exhibits a stable red seed coat phenotype due to the abundant accumulation of anthocyanins and proanthocyanidins (PAs). The regulatory mechanisms underlying PA biosynthesis in red walnut remain poorly studied, which hinders the improvement of walnut color quality. Leucoanthocyanidin reductase (LAR) is a key enzyme in the PA metabolic pathway, while its function in red walnut remains unclear. Here, the leucoanthocyanidin reductase gene JrLAR1, whose expression pattern is consistent with the accumulation trend of PAs, was cloned from the seed coats of red walnut ‘RW-1′, and its function in PA biosynthesis was verified via heterologous overexpression in Arabidopsis thaliana, a well-recognized cross-species LAR functional validation system free of endogenous LAR interference due to absent native homologs. The results showed that the full-length coding sequence (CDS) of JrLAR1 gene is 1104 bp, encoding a 367-amino-acid protein belonging to the NADB_Rossmann superfamily, and the protein shares an extremely high sequence similarity with grape VvLAR2. Heterologous overexpression of JrLAR1 significantly increased total PA content in the leaves and seeds of A. thaliana. Integrated transcriptomic and metabolomic analyses further revealed that JrLAR1 overexpression markedly upregulated the core genes involved in PA metabolism and the transcription factor GL3 in A. thaliana, specifically induced (+)-catechin synthesis, and ultimately promoted the significant accumulation of procyanidin B3. In addition, a set of antioxidant enzyme-encoding genes were substantially upregulated in JrLAR1-overexpressing A. thaliana lines. Yeast one-hybrid and dual-luciferase reporter assays demonstrated that JrEGL1b, a homolog of A. thaliana GL3, can bind to the promoter region of JrLAR1 gene and significantly enhance its transcriptional activity. Transient overexpression of JrLAR1 or JrEGL1b in red walnut leaves significantly promoted PA accumulation, and JrEGL1b overexpression notably upregulated JrLAR1 expression. In conclusion, JrLAR1 plays a crucial role in PA biosynthesis in red walnut and is positively regulated by the transcription factor JrEGL1b. These findings improve the molecular regulatory network of pigment metabolism in red walnut and provide valuable molecular targets for the quality improvement and directional breeding of walnuts.
Strawberry (Fragaria × ananassa) is an economically important berry rich in bioactive proanthocyanidins (PAs) with healthy benefits. The AP2/ERF gene family, one of the largest transcription factors (TFs) in plants, regulates diverse biological processes. However, its role in PA biosynthesis in strawberry remains unclear. In this study, comparative genomics of 39 species revealed lineage-specific expansion of AP2/ERF, primarily driven by whole-genome/segmental duplication. Integrated transcriptomic and metabolomic analyses of a high-PA natural mutant identified FaERF4 as a key positive regulator. Subcellular localization confirmed that FaERF4 localizes both the nucleus and cytoplasm. Transient/stable overexpression showed that FaERF4 significantly increased PA content and upregulated flavonoid genes without affecting anthocyanin accumulation. Mechanistically, FaERF4 specifically bound to and activated the promoters of FaLAR and FaANR, thereby promoting PA biosynthesis. This study reveals a novel mechanism by which FaERF4 specifically regulates PA biosynthesis and provides a theoretical basis for metabolic engineering of functional nutrients in strawberry.
Yi-Lin Yang, Si-Qi Dai, Hao Li et al.· Journal of Agricultural and...· 0 citations
This study clarifies the molecular basis and transcriptional regulation of phenolic acid glycosylation in P. chienii, providing a framework for exploiting its medicinal resources and guiding conservation-oriented breeding.
Xiaori Zhan, Zijing Zhou, Yuting Peng et al.· Plant and Cell Physiology· 1 citation
Fungal pigments hold significant food industrial value due to their safe and sustainable properties. Here we identified a naturally occurring coculture pair
Epicoccum nigrum
SPDX618 and
Mucor racemosus
SPDX522 in vinegar mash that produced red pigments, which was not observed in either monoculture. Our results showed that
E. nigrum
acted as the pigment producer while
M. racemosus
served as the elicitor. Response surface methodology and pH stabilization strategy improved the yield of red pigment into 328.7 U/g. Through bioactivity-guided fractionation coupled with UHPLC-MS/MS and in silico structure reconstitution, four red pigments were preliminarily assigned as anthracycline-like compounds. RNA-seq analysis revealed a putative dual-PKS gene cluster (SPDX618009169–SPDX618009178) with exclusively upregulation in cocultured
E. nigrum
that is potentially involved in red pigment biosynthesis. Besides, the production of the yellow pigment epipyrone was reduced in cocultured
E. nigrum
, consistent with the downregulated transcription level of its biosynthesis genes. Comparative metabolomics analysis further revealed a broad downregulation in both of primary metabolism and secondary metabolism in coculture system, indicating that a competition interaction relationship also existed between
E. nigrum
and
M. racemosus
. Altogether, this study reports a fungal coculture system that exhibited red pigments production. These findings contribute to the understanding of microbial interaction-driven metabolite biosynthesis and may provide a foundation for future exploration of their potential application as a colorant.
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An Epicoccum nigrum–Mucor racemosus coculture system was identified to produce red pigment for the first time.
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E. nigrum acts as the red pigment producer and M. racemosus serves as the elicitor.
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RNA-seq analysis tentatively identified a putative dual-PKS gene cluster upregulated in coculture that is putatively involved in red pigment biosynthesis.
Fengliu Wang, Fang Xu, Xinle Liang et al.· Applied Microbiology and Bio...· 0 citations
Leaf color variation is an important ornamental trait in bamboo and is primarily determined by chlorophyll accumulation. However, the molecular mechanisms underlying leaf color differentiation in Sinobambusa tootsik f. albostriata remain largely unclear. In this study, fully green (WG) and fully white (WW) leaf buds at three developmental stages (S1–S3) were analyzed to investigate the regulatory mechanisms associated with chlorophyll accumulation and identify key functional genes. Chlorophyll content determination, coproporphyrinogen III oxidase (CPOX) activity assays, and comparative transcriptome analysis were integrated to identify candidate genes involved in leaf color formation. Six StaHemF family members were identified, and StaHemF5 was selected as the primary candidate based on phylogenetic relationships and expression patterns. Compared with WG leaf buds, WW leaf buds exhibited significantly reduced chlorophyll contents and CPOX activities throughout development, indicating impaired chlorophyll biosynthesis. StaHemF5 encodes a chloroplast-localized protein and displays consistent expression trends between transcriptome analysis and qRT-PCR validation. Functional characterization revealed that transient overexpression of StaHemF5 in Nicotiana benthamiana significantly enhanced CPOX activity and chlorophyll accumulation, suggesting a positive role of StaHemF5 in chlorophyll biosynthesis. Collectively, these results demonstrate that StaHemF5 is a conserved HemF family member involved in chlorophyll accumulation and contributes to leaf color differentiation in S. tootsik f. albostriata. This study provides new insights into the molecular mechanisms underlying bamboo leaf color variation and identifies a potential candidate gene for the genetic improvement of ornamental bamboo.
Xin Gao, Zong-Hui Wei, Yu-Han Lin et al.· International Journal of Mol...· 0 citations
Soil salinization severely restricts the growth, yield, and industrial development of apricot (Prunus armeniaca L.). WRKY transcription factors play crucial roles in plant responses to abiotic stresses. However, the genome-wide characteristics of the WRKY family in apricot and their functional mechanisms in salt tolerance remain unclear. In this study, we identified 58 PaWRKY genes in apricot and characterized their phylogeny, chromosomal distribution, and gene structure. Based on transcriptomic and phylogenetic analyses, PaWRKY57 (homologous to AtWRKY33) was selected as a key salt-responsive candidate gene. Heterologous overexpression of PaWRKY57 in tobacco significantly enhanced salt tolerance; compared with the wild type, the transgenic lines exhibited a higher germination rate, better growth phenotype, lower accumulation of malondialdehyde (MDA) and reactive oxygen species (ROS), higher proline content, and stronger activities of antioxidant enzymes (SOD, POD, and APX). Protein-protein interaction prediction showed PaWRKY57 interacts with MPK3/4/6 and other stress-related proteins, and GO enrichment implicated it in osmotic stress and protein phosphorylation. This study provides preliminary genetic resources and a theoretical basis for research on the molecular mechanism of salt tolerance and stress-resistant molecular breeding in apricot.
The molecular evidence linking a PnTPS-derived gene to caryophyllene biosynthesis in P. nigrum is provided, highlighting its potential role in plant defense and paving the way for functional validation and genetic improvement strategies aimed at enhancing biotic stress resistance in black pepper.
Aparna K. S., Jaysree R. C., Geethalakshmi Sundararaman· Research journal of biotechn...· 0 citations
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