Comparison of salinity response of the cultivated tomato (Solanum lycopersicum) and its wild relative Solanum chilense during reproductive stage

Abiotic stresses as salinity affect glycophyte plants such as tomato (Solanum lycopersicum) at the whole-plant level. Although soil salinity is a growing problem in the world and tomato is the second most highly produced vegetable crop worldwide, little is known about traits that influence salt resistance at reproductive stage in this species. Reproductive stage is often more sensitive to abiotic stress than vegetative stage and represents thus a major issue for tomato industry. Resistance to salinity is a multi-gene mechanism and de novo domestication of wild relative species could be an efficient strategy to improve salt-resistance in cultivated tomato. The wild tomato Solanum chilense is able to cope with harsh environment and represents an abundance of genetic diversity for tomato improvement. However, physiological basis of salinity tolerance in S. chilense remains largely unknown. The aim of our research is to compare the changes mediated by salinity in S. chilense and S. lycopersicum during vegetative and reproductive stages. Plants of S. chilense and S. lycopersicum were grown under greenhouse conditions and were watered with Hoagland solution containing either 0, 60, 120 or 180 mM NaCl. Regarding vegetative parameters, salinity decreased the number of leaves of both species mainly at 120 and 180 mM NaCl. Regarding reproductive parameters, salt decreased the number of inflorescences and affected flower morphology in both species. Salt reduced stigma receptivity in S. lycopersicum but not in S. chilense. NaCl also reduced fruit dry weight and fruit size in S. lycopersicum while it only decreased fruit size in S. chilense. Regarding sodium concentration in the different organs, both species accumulated less Na in inflorescences than in vegetative parts. However, the inflorescences of S. lycopersicum accumulated more Na than the ones of S. chilense. Our results suggested thus that both species may differ in their sensitivity to NaCl at reproductive stag