The WRKY3 Transcription Factor SlWRKY3 Is Involved in Salt Stress Tolerance in Tomato.

Salinity threatens productivity of economically important crops such as tomato ( L.). WRKY transcription factors appear, from a growing body of knowledge, as important regulators of abiotic stresses tolerance. Tomato SlWRKY3 is a nuclear protein binding to the consensus CGTTGACC/T W box. is preferentially expressed in aged organs, and is rapidly induced by NaCl, KCl, and drought. In addition, responds to salicylic acid, and :: tomatoes showed under salt treatment reduced contents of salicylic acid. In tomato, overexpression of impacted multiple aspects of salinity tolerance. Indeed, salinized (125 mM NaCl, 20 days) tomato plants displayed reduced oxidative stress and proline contents compared to WT. Physiological parameters related to plant growth (shoot and root biomass) and photosynthesis (stomatal conductance and chlorophyll content) were retained in transgenic plants, together with lower Na contents in leaves, and higher accumulation of K and Ca. Microarray analysis confirmed that many stress-related genes were already up-regulated in transgenic tomatoes under optimal conditions of growth, including genes coding for antioxidant enzymes, ion and water transporters, or plant defense proteins. Together, these results indicate that SlWRKY3 is an important regulator of salinity tolerance in tomato.