From greenhouse conditions to the field: stability of tolerance to water deficit in the tomato wild relatives Solanum lycopersicum var. cerasiforme and Solanum pimpinellifolium

Breeding tomatoes for tolerance to water deficit (WD) has become a crucial goal amidst climate change scenarios marked by water shortages. Given the limited tolerance within the cultivated genepool, the red-fruited wild relatives Solanum lycopersicum var. cerasiforme (SLC) and Solanum pimpinellifolium (SP) are promising sources of valuable alleles. In this study, we utilized four SP and six SLC genotypes, chosen to represent broad genetic and ecogeographic diversity, to explore the stability of tolerance to WD across highly diverse experimental conditions, including early developmental stages (plantlet), greenhouse experiments (short and long cycles), and field conditions. The impact of WD on phenotypic traits exhibited a consistent direction across all experimental conditions: plant growth traits were negatively affected, whereas fruit quality traits demonstrated a positive response. Biomass partitioning into stems, leaves, and fruits remained unaffected by WD. The genotype-by-watering interaction emerged as the main factor driving the effect of WD on phenotyped biomarkers, indicating substantial genetic variation in phenotypic plasticity in response to WD conditions. Poor correlation was observed among plasticity indices obtained in different experimental conditions, underscoring the need for multi-environmental experiments to unravel the complex genetic architecture of WD tolerance. Two genotypes (SP2, SLC1) originally collected from arid areas of South-America were identified as promising sources of WD tolerance.