Abstract
Node is an important place for preferential distribution of minerals. We have identified the first transporter, Lsi6, which is involved in inter-vascular transfer of Si. Though microarray analysis, we have found a number of mineral transporters, which show higher expression in the node. Here we report one of them, OsNramp3, in terms of its function in mineral transport.
Nramp transporters are generally known as divalent metal cation transporter. OsNramp3 was highly expressed in rice nodes and localized at xylem transfer cells surrounding the enlarged vascular bundles. Transient expression of GFP fusion gene in onion epidermis revealed that OsNramp3 was targeted to the plasma membrane. When expressed in yeast, OsNramp3 complemented the growth of smf1 mutant defective in Mn uptake. However, there was no transport activity for Cd and Al. Knockout of OsNramp3 resulted in leaf chlorosis and root growth reduction under Mn deficiency condition. When grown in soil, the knockout line showed reduced Mn in the flag leaf blade, but increased Mn in the husk. Taken together, our results indicate that OsNramp3 is involved in Mn uptake by the roots and inter-vascular transfer of Mn in the node.
