Abstract
Barley accumulates glycinebetaine (betaine), which is one of the compatible solutes in the cytoplasmic compartments under salt stress. Betaine alleviates salinity-induced water loss and metabolic obstacles in plants. In this report, we investigated the contents of betaine and HvBADH2 mRNA in various organs of barley grown under salt stress. HvBADH2 gene codes for betaine aldehyde dehydrogenase (BADH) which catalyzes the last step of betaine synthesis. We identified that betaine contents increased in young leaves more than in old ones, and the expression levels of HvBADH2 mRNA sequentially shifted from old leaves to young ones. The tissue localization of HvBADH2 mRNA in the leaf blades was constitutively detected in the mesophyll tissues. Moreover, it was detected strongly in the phloem under salt stress. It was also detected endodermis and exodermis in the roots. We further determine the localization of BADH protein and H2O2 that might induce betaine synthesis in the tissues.
