title: Natural variation underlies alterations in Nramp aluminum transporter (NRAT1) expression and function that play a key role in rice aluminum tolerance.
abstract: Aluminum (Al) toxicity is a major constraint for crop production on acid soils which compose ∼ 40% of arable land in the tropics and subtropics. Rice is the most Al-tolerant cereal crop and offers a good model for identifying Al tolerance genes and mechanisms. Here we investigated natural variation in the rice Nramp aluminum transporter (NRAT1) gene encoding a root plasma membrane Al uptake transporter previously hypothesized to underlie a unique Al tolerance mechanism. DNA sequence variation in the NRAT1 coding and regulatory regions was associated with changes in NRAT1 expression and NRAT1 Al transport properties. These sequence changes resulted in significant differences in Al tolerance that were found to be associated with changes in the Al content of root cell wall and cell sap in 24 representative rice lines from a rice association panel. Expression of the tolerant OsNRAT1 allele in yeast resulted in higher Al uptake than did the sensitive allele and conferred greater Al tolerance when expressed in transgenic Arabidopsis. These findings indicate that NRAT1 plays an important role in rice Al tolerance by reducing the level of toxic Al in the root cell wall and transporting Al into the root cell, where it is ultimately sequestered in the vacuole. Given its ability to enhance Al tolerance in rice and Arabidopsis, this work suggests that the NRAT1 gene or its orthologs may be useful tools for enhancing Al tolerance in a wide range of plant species.
authors.affiliation: Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, NY 13853.
authors.forename: Jian-Yong
authors.initials: JY
authors.lastname: Li
authors.forename: Jiping
authors.initials: J
authors.lastname: Liu
authors.forename: Dekun
authors.initials: D
authors.lastname: Dong
authors.forename: Xiaomin
authors.initials: X
authors.lastname: Jia
authors.forename: Susan R
authors.initials: SR
authors.lastname: McCouch
authors.forename: Leon V
authors.initials: LV
authors.lastname: Kochian
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics*; D000483:Alleles; D000535:Aluminum / Q000633:toxicity*; D017360:Arabidopsis / Q000235:genetics; D002473:Cell Wall / Q000187:drug effects / Q000378:metabolism; D060146:Ecotype; D018506:Gene Expression Regulation, Plant / Q000187:drug effects*; D014644:Genetic Variation; D006239:Haplotypes / Q000235:genetics; D016366:Open Reading Frames / Q000235:genetics; D012275:Oryza / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000378:metabolism; D030821:Plants, Genetically Modified; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D011401:Promoter Regions, Genetic / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000378:metabolism
chemical_list: D010940:Plant Proteins; D000535:Aluminum
keywords: aluminum transport; cell wall aluminum
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