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- Understanding the transition from embryogenesis to seed filling in Phaseolus vulgaris L. non-endospermic seedsPublication . Lopes, Cláudia; Fevereiro, Pedro; Araújo, Susana; Araújo, Susana de SousaCommon bean (Phaseolus vulgaris L.) is one of the most consumed grain legumes. These legumes are a major source of proteins and other important nutrients, especially in developing countries. Studying seed development in common bean is crucial for improving yield, nutrition, stress tolerance and disease resistance while promoting sustainable agriculture and food security, with its sequenced genome and available molecular tools making it an excellent research model. Despite advances in studying P. vulgaris seed development, the precise timing and molecular regulation of the transition from embryogenesis to seed filling remain poorly understood. Although P. vulgaris seeds at 10 days after anthesis (DAA) were previously characterized as being in the late embryogenesis stage, our previous studies suggested that this transition might occur earlier than 10 DAA, prompting us to investigate earlier developmental stages.Methods To accomplish this goal, we conducted a comprehensive analysis at 6, 10, 14, 18 and 20 DAA, integrating morphological, histological, and transcriptomic approaches.Results and discussion Morphological and histochemical data revealed that by 10 DAA, cotyledons are fully formed, but storage compound accumulation is only noticed at 14 DAA, indicating that the transition from embryogenesis to seed filling occurs between 10 and 14 DAA. Transcriptomic analysis further supported this finding, showing upregulation of genes associated with seed storage proteins, starch metabolism, and hormonal regulation at 14 and 18 DAA. This study redefines the developmental timeline of P. vulgaris seed filling initiation, bridging a critical knowledge gap in legume seed biology. Given the limited availability of histological studies on early P. vulgaris seed development, our findings provide essential insights into the structural and molecular events driving this transition. By refining the timing and regulatory mechanisms of early seed development, this study lays the groundwork for future research aimed at enhancing seed quality and resilience in legumes.
- Integrating natural variation through GWAS – genetics of drought and flood tolerance in grass pea reveal independent yet interconnected mechanismsPublication . Sanches, Matilde; Vuylsteke, Marnik; Santos, Carmen; Mhamdi, Amna; Araújo, Susana de Sousa; Breusegem, Frank Van; Patto, Maria Carlota VazGrass pea (Lathyrus sativus L.) is a grain legume of increasing importance in the Mediterranean region due to its outstanding tolerance to abiotic stresses such as salinity, heat, drought, and flooding, outperforming many other legume species. Despite established natural phenotypic variation in response to water-related stresses, the genetic basis of this resilience remains poorly understood, hindering precision breeding for single and combined stress tolerance. A genome-wide association study was conducted here to investigate the genetic architecture of water stress responses in grass pea. Previously, phenotypic data, including gas exchange, chlorophyll a fluorescence, photosynthetic pigments, leaf water status, and biomass partitioning traits, were assessed under well-watered, mild drought, and partial submergence conditions across 194 representative grass pea accessions worldwide. The data were associated with 5,651 single nucleotide polymorphisms (SNPs) using linear mixed models under a restricted maximum likelihood framework, incorporating population structure and the newly assembled L0007 genome. A total of 130 unique SNPs associated with at least one trait-treatment combination or with trait variation between stress and control conditions, providing a valuable resource for precision breeding of multi-stress tolerance in grass pea. The loci associated with drought and waterlogging were largely non-overlapping, suggesting distinct genetic bases for the two stress tolerances. However, some common mechanisms, such as redox regulation and carbohydrate metabolism, emerged among the identified candidate genes, highlighting some interconnectedness of biological pathways involved in grass pea responses to water stress.