Expression of a monothiol glutaredoxin, AtGRXS17, in tomato (Solanum lycopersicum) enhances drought tolerance.

Abiotic stresses are a major factor limiting crop growth and productivity. The Arabidopsis thaliana glutaredoxin S17 (AtGRXS17) gene has conserved functions in plant tolerance to heat and chilling stress in Arabidopsis and, when expressed ectopically, in tomato. Here, we report that ectopic expression of AtGRXS17 in tomato also enhanced tolerance to drought and oxidative stress. AtGRXS17-expressing tomato plants contained twice the shoot water content compared to wild-type plants under water limiting conditions. This enhanced drought tolerance correlated with a higher maximal photosynthetic efficiency of photosystem II (Fv/Fm). Ectopic AtGRXS17-expression was concomitant with the expression of Solanum lycopersicum catalase 1 (SlCAT1) and mitigated defects in the growth of primary roots in response to methyl viologen exposure. In addition, AtGRXS17 expression was found to prolong elevated expression levels of the Solanum lycopersicum ABA-responsive element binding protein 1 (SlAREB1) during drought stress. The findings demonstrate that expression of AtGRXS17 can simultaneously improve the tolerance of tomato, and possibly other agriculturally important crops, to drought, heat, and chilling stresses.