Multi-level approach to screen tomato inbred lines for resilience to Ni-enriched soils and water deficit

• Differential responses of tomato inbred lines to Ni and water stress • Ni stress resilience is linked to low mineral imbalance • Water stress resilience relates to recovery from repeated drought-stress events Climate-driven increases in drought occurrence and the contamination of soils by heavy metals adversely affect tomato production both qualitatively and quantitatively. The aim of the present study was to investigate the responses of four inbred lines of Solanum lycopersicum to Ni toxicity and water deprivation. To evaluate the effects of Ni, we used two different growth approaches, in hydroponics and in soil, associating a morphological analysis of the lines with Ni and mineral nutrient quantification in both shoots and fruits. The effects of water stress were tested on germination capacity in vitro and on adult plants grown in soil. The responses of the different lines to water stress were assessed by physiological and phenotypic analyses, expression of drought-related genes and quantification of ABA. The multi-level approach allowed us to identify two lines, among the four investigated, as good candidates for future breeding programs due to their ability to accumulate less Ni and maintain fruit quality parameters and capacity to acclimate to repeated water stress.