Using proteomics to understand seed development in Phaseolus vulgaris L.: developing resources to modulate seed quality traits

Common bean (Phaseolus vulgaris L.) is the most consumed grain legume in developing countries in Latin America and Sub-Saharan Africa1. Like other legumes, common bean seeds are rich in protein, carbohydrates, fibers and other health-promoting phenolic compounds thus being vital for food security and income source for local small farmers2. Seed quality traits depend on accumulation of various storage molecules during the seed development (SD) process and influenced by the genotype and adaptive changes to environment3. Concerning common bean, there is still a lack of a deeper molecular knowledge of SD that is hampering the development of new biotech approaches for seed trait modulation and could timely address challenges of agriculture or industry. Our present work aims to unravel the molecular mechanisms underlying SD using a proteomic approach. To achieve this goal, we characterized SD in terms biomass, seed length and weight in the genotype SER16, one of the most promissory drought-resistant release of the CIAT-CGIAR. Seed samples were collected at the 4 main SD stages: Late-Embryogenesis (10 days after anthesis, d.a.a.), Early (20 d.a.a.) and Late Maturation (30 d.a.a.) and Desiccation (40 d.a.a.). The analysis of bean proteome was conducted using a gel-free proteomic analysis (LC-MS/MS) under the scope of EU-FP7-PRIME-XS project. A total of 410 unique proteins were differentially expressed throughout the 4 major seed development stages, in which most of the identified proteins belong in the ‘protein metabolism’ (31,98%) functional category, that includes synthesis, regulation, folding. Other functional categories are represented such as carbohydrate and lipid metabolism (11,26%) and stress/defense and redox metabolism (11,04%). We identified 93 proteins were unique to the first (10-20 d.a.a.), 22 to the second (20-30 d.a.a.) and 40 to the last (30-40 d.a.a.) phase transition, reflecting the major biological processes occurring at this specific seed developmental stage. This study will contribute to reveal key metabolic pathways and mechanisms with potential role in modulating common bean seed development and quality traits.