ORIGINAL RESEARCH article
Front. Plant Sci.
Sec. Plant Metabolism and Chemodiversity
Volume 16 - 2025 | doi: 10.3389/fpls.2025.1595906
This article is part of the Research TopicEvolution, Accumulation and Metabolic Engineering of Plant Secondary MetabolitesView all 6 articles
Molecular Insights into Postharvest Seed Coat Darkening in Common Beans: A Look Beyond the P Gene
Provisionally accepted
- 1London Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), London, Canada
- 2Department of Biology, Western university, London, Canada
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Many market classes of common beans (Phaseolus vulgaris) have a significant reduction in crop value due to the postharvest darkening of the seed coat. Seed coat darkening is caused by an elevated accumulation and oxidation of proanthocyanidins (PAs). In common bean, the major color gene P encodes for a bHLH protein with its P sd allele controlling the postharvest slow darkening seed coat trait. In the present investigation, we determined that P/ P sd , PvMYB3A, and PvWD9 are the essential components that form a protein complex and regulate PA biosynthesis in pinto beans. P does not bind with the PA biosynthetic gene Anthocyanin Reductase (PvANR) promoter but regulates its expression by interacting with PvMYB3A, which directly binds to the PvANR promoter. PvWD9 is an essential member of the core protein complex, which requires one or more additional plant components in order to interact with its partner proteins P and PvMYB3A and create a functioning complex. The P sd isoform affects the accumulation of PA by functioning in a similar manner to its isoform P, albeit at a lower efficiency. Understanding the regulation of PA biosynthesis in common beans helps to explain variances in seed coat color and issues associated with darkening after harvest.
Keywords: common bean, gene regulation, transcriptional complex, Proanthocyanidins, Seed coat color
Received: 18 Mar 2025; Accepted: 14 Jul 2025.
Copyright: © 2025 Islam and Dhaubhadel. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Sangeeta Dhaubhadel, London Research and Development Centre, Agriculture and Agri-Food Canada (AAFC), London, Canada
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