OsFRDL1

• Symbol: OsFRDL1
• MSU: LOC_Os03g11734
• RAPdb: Os03g0216700

• OsFRDL1 is a citrate transporter required for efficient translocation of iron in rice, 2009, Plant Physiol.
• A rice FRD3-like OsFRDL1 gene is expressed in the cells involved in long-distance transport, 2004, Soil Science and Plant Nutrition.
• OsFRDL1 expressed in nodes is required for distribution of iron to grains in rice., 2016, J Exp Bot.

Genbank accession number

• These results suggest that OsFRDL1 is a transporter that resides in the plasma membrane of cells involved in long-distant transport
• Here, we report the function of a rice (Oryza sativa) MATE gene (Os03g0216700, OsFRDL1), the closest homolog of barley (Hordeum vulgare) HvAACT1 (aluminum [Al]-activated citrate transporter 1), in terms of metal stress (iron [Fe] deficiency and Al toxicity)
• Furthermore, OsFRDL1 expression was observed during the reproductive stage
• Of these, we cloned three OsFRDL genes from a cDNA library prepared from iron-deficient rice roots: OsFRDL1, OsFRDL2, and OsFRDL3
• Taken together, our results indicate that OsFRDL1 is a citrate transporter localized at the pericycle cells, which is necessary for efficient translocation of Fe to the shoot as a Fe-citrate complex
• OsFRDL1 is a citrate transporter required for efficient translocation of iron in rice
• Immunostaining showed that OsFRDL1 was localized at the pericycle cells of the roots
• OsFRDL1 was expressed weakly in Fe-sufficient roots, and slight expression was induced in the roots of Fe-deficient plants
• OsFRDL1 was expressed in most cells of enlarged vascular bundles, diffuse vascular bundles, and the interjacent parenchyma cell bridges of uppermost node I, as well as vascular tissues of the leaf blade, leaf sheath, peduncle, rachis, husk, and stamen
• Iron was deposited in the parenchyma cell bridges, a few of the cell layers of the parenchyma tissues outside of the bundle sheath of enlarged vascular bundles in node I in both the wild-type rice and osfrdl1 mutant, but the mutant accumulated more Fe than the wild-type rice in this area
• We found that OsFRDL1 (FERRIC REDUCTASE DEFECTIVE LIKE 1), a plasma membrane-localized transporter for citrate, was highly expressed in the upper nodes of rice at the reproductive growth stage
• Knockout of OsFRDL1 decreased pollen viability and grain fertility when grown in a paddy field
• OsFRDL1 expressed in nodes is required for distribution of iron to grains in rice.

• OsFRDL1, OsFRDL2, Functional analysis of a MATE gene OsFRDL2 revealed its involvement in Al-induced secretion of citrate, but less contribution to Al tolerance in rice., A double mutant between osfrdl2 and osfrdl4 or osfrdl1 did not further decrease the Al-induced citrate secretion and Fe translocation compared with the single mutant