2006 Volume 23 Issue 4 Pages 357-364
We identified a 23 kDa protein expressed abundantly in young barley seedlings; this protein was named P23k. P23k was shown to have evolved in barley and its allied species such as wheat, oat and rye, suggesting that P23k might be closely related to a specific biological trait of winter cereals. To determine the function of P23k, we examined the expression and localization of P23k and its mRNA in barley seedlings. P23k mRNA was markedly expressed in the scutellum of imbibed barley seeds, and was synchronously down-regulated with consumption of the starchy endosperm. In addition, ABA and sugar treatment of the scutellum showed that expression of P23k is highly dependent on the supply of glucose or sucrose, both of which are starch catabolites. Furthermore, immunocytochemical analysis showed that P23k is primarily localized around the membranes, where sugar translocation is active. These results indicate that P23k plays a role in sugar translocation in young barley seedlings.
