HMA2 — Oryza sativa Japonica

Summary

Rice HMA2 (Os07g0232900, also known as HMA3 or OsHMA4) encodes a P-type heavy metal ATPase (EC 7.2.2.12, 7.2.2.21) with cation-transporting ATPase activity, including cadmium-exporting, copper, and zinc transporter activities. The protein localises to the vacuolar membrane, Golgi, plasmodesmata, and plasma membrane. In rice, HMA2 is associated with cadmium transport from roots to shoots, root elongation, and drought stress tolerance. It is linked to detoxification of cadmium and copper ions, copper and zinc ion homeostasis, phloem loading, and response to cobalt. The gene has been connected to agronomic traits including grain yield, plant height, chlorophyll content, root and shoot cadmium content, zinc concentration, leaf relative water content, and bacterial disease response. Studies of related genes in other species link the family to zinc translocation, cadmium accumulation, and seed zinc content.