Os02g0131800

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Annotated Information

Function

This gene is called Nramp(natural resistance-associated macrophage protein) aluminum transporter 1, which is a member of Nramp family and it is a plasma membrane-localized aluminum transporter recently identified in rice. We all known that the Aluminum (Al) is the most abundant metal in the Earth's crust, but its trivalent ionic form is highly toxic to all organisms at low concentrations. While the rice has the most Al-tolerant cereal crop and the researcher has found that the tolerant of aluminum is concerned with this gene. When expressed in yeast, Nrat1 transports trivalent Al ion, but not other divalent ions, such as manganese, iron, and cadmium, or the Al–citrate complex. Nrat1 is localized at the plasma membranes of all cells of root tips except epidermal cells. Knockout of Nrat1 resulted in decreased Al uptake, increased Al binding to cell wall, and enhanced Al sensitivity, but did not affect the tolerance to other metals. Expression of Nrat1 is up-regulated by Al in the roots and regulated by a C2H2 zinc finger transcription factor (ART1). We therefore concluded that Nrat1 is a plasma membrane-localized transporter for trivalent Al, which is required for a prior step of final Al detoxification through sequestration of Al into vacuoles.

Expression

The Nramp aluminum transporter (NRAT1) gene encoding a root plasma membrane Al uptake transporter previously hypothesized to underlie a unique Al tolerance mechanism. The research have found that genotypes of the 24 diverse lines assayed by sequencing a 3.7-kb region, including the 2.1-kb promoter region (M1 to M7) and a 1,638-bp coding sequence (M8 to M15). Fifteen natural mutation sites were identified (M1 to M15) based on comparison of the Nipponbare NRAT1 sequence, including 14 SNPs and one 7-bp insertion (M7). A total of five haplotypes were identified among the 24 diverse rice lines. Mutation sites marked with a red rectangle result in amino acid alterations. Also shown in the column labeled TRG-RRG is the Al tolerance for each group, based on the RRG of the total root system (TRG, total root growth).Jian-Yong Li et al. have cloned several lines of this gene into a yeast expression vector and transformed into yeast cells. And they investigated whether the altered amino acid sequences in NRAT1 affect its ability to transport Al.

Evolution

Conserved Domains from CDD found in protein sequences by rpsblast searching.

Labs working on this gene

1.Thompson Institute for Plant Research, Cornell University, Ithaca.

2.Robert W. Holley Center for Agriculture and Health, Agricultural Research Service, US Department of Agriculture, Cornell University, Ithaca.

3.Institute of Crop and Nuclear Technology Utilization, Zhejiang Academy of Agricultural Sciences, Hangzhou, China.

4.Department of Plant Breeding, Cornell University, Ithaca.

5.Institute for Plant Science and Resources, Okayama University, Japan.

References

1.Jian-Yong Li, Jiping Liu, Dekun Dong, Xiaomin Jia, Susan R. Mc Couch, and Leon V. Kochian, Natural variation underlies alterations in Nramp aluminum transporter (NRAT1) expression and function that play a key role in rice aluminum tolerance, PNAS, April 29, 2014.

2.Jixing Xia, Naoki Yamaji, Tomonari Kasai, and Jian Feng Ma, Plasma membrane-localized transporter for aluminum in rice, PNAS, October 26, 2010.

3.Xia J, Yamaji N, Ma JF, Further characterization of an aluminum influx transporter in rice. Plant Signaling & Behavior, January 2011.

4.Xia J, Yamaji N, Che J, Shen RF, Ma JF, Differential expression of Nrat1 is responsible for Al-tolerance QTL on chromosome 2 in rice, J Exp Bot. May 12,2014.

5.Famoso AN, Zhao K, Clark RT, Tung CW, Wright MH, Bustamante C, Kochian LV, McCouch SR, Genetic architecture of aluminum tolerance in rice (Oryza sativa) determined through genome-wide association analysis and QTL mapping, Aug 2011.