Genome-wide characterization of the tomato SlMGR gene family and the biological function of SlMGR10 in bacteria and Arabidopsis.

BACKGROUND AND AIMS: Magnesium is an essential mineral nutrient with numerous physiological roles in plant growth and development. However, the mechanisms of Mg2+ transport in Solanum lycopersicum remain largely unknown. METHODS: In this study, we performed the characterization of the Magnesium Release family genes (SlMGRs) in tomato. The conserved evolutionary relationship and expression pattern of SlMGR genes, and the subcellular localization and Mg2+ transport activity of SlMGR proteins, were investigated. KEY RESULTS: A total of ten SlMGR proteins were identified. They were divided into three subgroups based on their evolutionary relationship and subcellular localization. Four members in clade I were vacuolar localized, five members in clade II were plasma membrane localized, whereas SlMGR10, the sole member in clade III, was chloroplast envelope localized. SlMGR10 could successfully complement the growth defects of MM281, a bacterial Mg2+ uptake mutant, under Mg-limited conditions. It was also able to rescue the severe defects in embryo development and seedling growth of the Arabidopsis mgr8mgr9 double mutant caused by Mg deficiency during chloroplast development. CONCLUSIONS: Our results demonstrated that SlMGR10 functioned as a chloroplast envelope Mg2+ transporter to mediate Mg2+ uptake for chloroplast in Solanum lycopersicum.