Abstract
Barley is cultivated widely in the world and has developed strategies to overcome various stress. In this symposium, the mechanisms of tolerance to Al-toxicity and Fe-deficiency are focused. Barley is an Al-sensitive species, while there is a large genotypic variation between cultivars. Secretion of citrate has been associated with Al tolerance in barley and a gene responsible for Al-induced citrate secretion has been mapped to chromosome 4H. On the other hands, barley is very tolerant of Fe deficiency. Iron acquisition by barley is characterized by the secretion of the phytosiderophore (PS) and by a specific uptake system for iron(III)-PS complex. A gene encoding an iron-PS transporter (HvYS1) was cloned. HvYS1 gene was mainly expressed in the roots and the expression was enhanced under Fe-deficiency. In situ hybridization and immunostaining revealed that HvYS1 was localized at epidermal cells of roots. Furthermore, HvYS1 showed strict specificity for both metals and ligands.
