Dynamic of nitrogen acquisition and nitrogen partitioning in two common bean genotypes, a marker of tolerance in response to terminal drought

• Early N acquisition strategy led to unchanged seed N status in droughted plants • papain-like cysteine proteases play a major role in drought-accelerated senescence • cysteine proteinase mucunain-like was the main active PLCP enhanced by drought Climate change models predict increased drought frequency and severity, a threat to rain-fed crops like common bean ( Phaseolus vulgaris L.). Drought adversely affects plant growth, reducing crop yield and quality by limiting carbon (C) and nitrogen (N) supply. While carbon partitioning and sink-source relationships under drought have been extensively studied, the role of nitrogen remobilisation in drought tolerance remains underexplored. This study compares C metabolism and N remobilisation in two common bean genotypes, S156 and R123, submitted to a terminal drought. In response to water limitation, S156 plants exhibited earlier leaf proteolysis notably via a stimulation of papain-like cysteine proteases activity and enhanced nitrogen remobilisation. Both processes were likely responsible for the absence of impact of the terminal drought on the N status of S156 seeds and were sustained by early N acquisition. In comparison, N acquisition and accumulation in R123 relied more on N uptake balanced between vegetative and reproductive stages. We speculated that late N acquisition in R123 was hindered by the terminal drought treatment, and that was not compensated for by drought-induced N remobilisation. These findings highlighted distinct carbon and nitrogen strategies and underscored the importance of N remobilisation for drought tolerance in common bean.