Molecular regulation of pod development in legume: genetic networks, hormonal control and breeding applications

Legume pods represent one of the most morphologically diverse and economically significant fruit types in the plant kingdom, serving as both reproductive organs and critical nutritional sources for global food security. Unlike the dehiscent siliques of the Brassicaceae model Arabidopsis thaliana , legume pods exhibit extraordinary developmental plasticity, encompassing both dehiscent dry pods adapted for seed dispersal and indehiscent fleshy pods. This review synthesizes the molecular regulatory networks governing legume pod development, with an emphasis on carpel patterning, pericarp differentiation, and the evolutionary conservation versus legume-specific innovations underlying trait determination. We compared the canonical ABCDE floral organ identity model between Arabidopsis and core legume species, including soybean ( Glycine max ), common bean ( Phaseolus vulgaris ), pea ( Pisum sativum ), and Medicago truncatula , revealing how lineage-specific gene duplications and expression reprogramming of MADS-box genes have shaped legume-specific developmental features. Furthermore, we dissected the multilayered regulatory pathways controlling pod size, dehiscence, pericarp texture, and color, integrating hormone signaling, transcription factor networks, epigenetic modifications, and non-coding RNA-mediated regulation. By bridging fundamental developmental biology with applied breeding science, we compiled validated QTLs, functional markers, and CRISPR-Cas9 editing targets for pod trait improvement in major legume crops. Finally, we propose three critical scientific questions: the molecular mechanisms maintaining carpel margin meristem activity, the integration of epigenetic memory with environmental signals during pericarp maturation, and the regulatory switches governing the dehiscence-to-indehiscence transition, alongside three breeding priorities: precision editing of pod dehiscence genes for mechanical harvesting, molecular marker pyramiding of multi-trait QTLs, and genomic accelerated domestication of underutilized legume species.