Islam Nishat S, Dhaubhadel Sangeeta
London Research and Development Centre, Agriculture and Agri-Food Canada, London, ON Canada.
Department of Biology, University of Western Ontario, London, ON Canada.
Phytochem Rev. 2025;24(4):2445-2461. doi: 10.1007/s11101-023-09895-8. Epub 2023 Oct 12.
Proanthocyanidins (PAs) are polyphenolic compounds present widely in the plant kingdom. These specialized metabolites are derived from the phenylpropanoid pathway and are known for producing brown pigments in different plant organs. PAs accumulate in the seed coat tissues of flowering plants and play a determinant role in seed germination and viability, protect seeds from biotic and abiotic stresses, and thus ensure the long-term storage potential of seeds. In addition, PAs are a rich source of antioxidants for the health of both human and livestock. Many of the commercially relevant dry beans () contain high levels of PAs, which when oxidized cause the beans to overdarken, a phenomenon known as postharvest darkening. These darker beans give the impression of oldness, and consumers tend to avoid buying them which, in turn, affects their market value. Pinto beans, one of the leading market classes of dry beans, are affected the most by the postharvest darkening. Therefore, exploring the regulation of PA biosynthesis and accumulation in bean seed coat tissues will help to develop strategy to manage the postharvest darkening effect in pintos. In this review, we discuss the PA biosynthesis and its regulation, connecting it to seed coat color genetics for a better understanding of the mechanism of seed coat darkening.
原花青素（PAs）是广泛存在于植物界的多酚类化合物。这些特殊的代谢产物源自苯丙烷类途径，以在不同植物器官中产生褐色色素而闻名。PAs在开花植物的种皮组织中积累，在种子萌发和活力方面起决定性作用，保护种子免受生物和非生物胁迫，从而确保种子的长期储存潜力。此外，PAs是人类和牲畜健康的丰富抗氧化剂来源。许多具有商业价值的干豆含有高水平的PAs，氧化时会导致豆子过度变黑，这种现象称为采后变黑。这些颜色较深的豆子给人陈旧的印象，消费者往往会避免购买，这反过来又会影响它们的市场价值。斑豆是干豆的主要市场类别之一，受采后变黑的影响最大。因此，探索豆种皮组织中PA生物合成和积累的调控将有助于制定管理斑豆采后变黑效应的策略。在这篇综述中，我们讨论了PA生物合成及其调控，并将其与种皮颜色遗传学联系起来，以更好地理解种皮变黑的机制。
