Involved in osmotic and salt stress tolerance. May play a role in the control of meristematic cell size during osmotic stress. May function as an adaptor protein for BRL2 and may be required for signaling affecting leaf vascular tissue pattern formation. Interacts with BRL2. Expressed in embryos and organ primordia in shoot and root. In primary and cauline leaves and petals, is expressed in hydathodes, guard cells, petiole cells and cells associated with differentiating vascular bundles. By salt treatment in cotyledons and cold stress in pollen. The thioredoxin domain is inactive. Altered vein pattern in cotyledons and primary leaves. Mutant seedlings show increased sensitivity to osmotic and salt stresses in roots.