HMA4 — Brassica napus

Summary

BnHMA4 (HMA4) on chromosome A07 of oilseed rape encodes a P-type ATPase of the IB subfamily, a heavy metal-transporting ATPase with domains characteristic of cation transporters. It is annotated with multiple divalent and monovalent cation transporter activities, including those for copper, zinc, cadmium, calcium, potassium and sodium, as well as copper binding and calmodulin binding. The gene is associated with metal ion homeostasis and detoxification, specifically responses to cadmium, cobalt, copper and zinc, and with processes such as pollen germination, brassinosteroid-mediated signalling and response to cold. It has been linked to traits including photosynthetic rate, germination rate, nitrate uptake and stomatal resistance, and to phenotypes such as cadmium tolerance and translocation, zinc concentration gradients, and fungal resistance. The protein is localised to the vacuolar membrane, Golgi, plasmodesmata, mitochondria and plasma membrane. Related genes in other species are associated with zinc and cadmium translocation, metal homeostasis, and seed zinc content.