A Bacterial-Type ABC Transporter Is Involved in Aluminum Tolerance in Rice
A Bacterial-Type ABC Transporter Is Involved in Aluminum Tolerance in Rice
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DOI：
10.1105/tpc.108.064543
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发表时间：
2009-02-01
期刊：
影响因子：
11.6
通讯作者：
Ma, Jian Feng
中科院分区：
文献类型：
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作者：
Huang, Chao Feng;Yamaji, Naoki;Ma, Jian Feng
铝（Al）毒性是酸性土壤中限制作物生产的主要因素，但铝耐受性的分子机制尚不清楚。在这里，我们报道了两个基因，STAR1（对铝根毒性敏感的基因1）和STAR2，负责水稻的铝耐受性。STAR1编码一个核苷酸结合域，而STAR2编码一个细菌型ATP结合盒（ABC）转运体的跨膜结构域。任何一个基因的破坏都会导致对铝毒性的超敏反应。STAR1和STAR2主要在根中表达，受铝暴露特异性诱导。在洋葱表皮细胞、水稻原生质体和酵母中的表达表明，STAR1与STAR2相互作用形成一个复合物，该复合物定位于除成熟区表皮层外的所有根细胞的囊泡膜上。当在非洲爪蟾卵母细胞中同时表达时，STAR1/2显示出udp -葡萄糖特异性的外排转运活性。此外，在暴露于Al的star1突变体中，外源udp -葡萄糖的添加恢复了根系生长。这些结果表明，star1和STAR2形成了一个复合物，作为ABC转运体，这是水稻解毒所必需的。ABC转运蛋白运输可用于修饰细胞壁的udp -葡萄糖。
Aluminum (Al) toxicity is a major factor limiting crop production in acidic soil, but the molecular mechanisms of Al tolerance are poorly understood. Here, we report that two genes, STAR1 (for sensitive to Al rhizotoxicity1) and STAR2, are responsible for Al tolerance in rice. STAR1 encodes a nucleotide binding domain, while STAR2 encodes a transmembrane domain, of a bacterial-type ATP binding cassette (ABC) transporter. Disruption of either gene resulted in hypersensitivity to aluminum toxicity. Both STAR1 and STAR2 are expressed mainly in the roots and are specifically induced by Al exposure. Expression in onion epidermal cells, rice protoplasts, and yeast showed that STAR1 interacts with STAR2 to form a complex that localizes to the vesicle membranes of all root cells, except for those in the epidermal layer of the mature zone. When expressed together in Xenopus laevis oocytes, STAR1/2 shows efflux transport activity specific for UDP-glucose. Furthermore, addition of exogenous UDP-glucose rescued root growth in the star1 mutant exposed to Al. These results indicate that STAR1 and STAR2 form a complex that functions as an ABC transporter, which is required for detoxification of Al in rice. The ABC transporter transports UDP-glucose, which may be used to modify the cell wall.