Deficiency in alcohol dehydrogenase 2 reduces arsenic in rice grains by suppressing silicate transporters
Deficiency in alcohol dehydrogenase 2 reduces arsenic in rice grains by suppressing silicate transporters
复制标题
乙醇脱氢酶2的缺乏通过抑制硅酸盐转运蛋白来减少米粒中的砷
DOI：
10.1093/plphys/kiab086
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发表时间：
2021
期刊：
影响因子：
7.4
通讯作者：
Ishikawa Satoru
中科院分区：
文献类型：
--
作者：
Hayashi Shimpei;Kuramata Masato;Abe Tadashi;Yamaguchi Noriko;Takagi Hiroki;Tanikawa Hachidai;Iino Manaka;Sugimoto Kazuhiko;Ishikawa Satoru
稻田是厌氧的，有利于亚砷酸盐（As（III））从土壤中洗脱。稻田水稻积累砷（As）在其籽粒中，因为硅酸盐运输积极吸收As（III）在生殖阶段。降低稻米中的砷含量是农业面临的一个重要挑战。利用正向遗传方法，我们分离出一个水稻（Oryza sativa）突变体，低砷线3（las 3），其As水平下降的气生组织，包括粮食。低砷表型没有观察到在年轻的植物抽穗前（出现穗）。遗传分析表明，缺乏乙醇脱氢酶（ADH）2的突变是负责的表型。在三种水稻ADH旁系同源物中，ADH 2在厌氧条件下在根组织中产生的效率最高。在野生型（WT），硅和As浓度在气生组织中的增长。而在繁殖期las 3的增加受到抑制。因此，两种硅酸盐转运蛋白Lsi 1和Lsi 2的基因表达在WT中在抽穗前后增加，而这种增加在las 3中被抑制。这些结果表明，低砷表型inlas 3是由于硅酸盐转运抑制。通过~（31）P-核磁共振测定细胞内pH值，发现缺氧条件下flas 3根细胞内酸化，表明硅酸盐转运体抑制inlas 3可能是由于细胞内pH值降低所致，而这可能是由于缺氧条件下ADH活性不足所致。这项研究为降低稻米中的砷含量提供了有价值的见解。
Paddy fields are anaerobic and facilitate arsenite (As(III)) elution from the soil. Paddy-field rice accumulates arsenic (As) in its grains because silicate transporters actively assimilate As(III) during the reproductive stage. Reducing the As level in rice grains is an important challenge for agriculture. Using a forward genetic approach, we isolated a rice (Oryza sativa) mutant,low arsenic line 3(las3), whose As levels were decreased in aerial tissues, including grains. The low-As phenotype was not observed in young plants before heading (emergence of the panicle). Genetic analyses revealed that a deficiency in alcohol dehydrogenase (ADH) 2 by mutation is responsible for the phenotype. Among the three rice ADH paralogues, ADH2 was the most efficiently produced in root tissue under anaerobic conditions. In wild-type (WT), silicon and As concentrations in aerial tissues increased with growth. However, the increase was suppressed inlas3during the reproductive stage. Accordingly, the gene expression of two silicate transporters, Lsi1 and Lsi2, was increased in WT around the time of heading, whereas the increase was suppressed inlas3. These results indicate that the low-As phenotype inlas3is due to silicate transporter suppression. Measurement of intracellular pH by31P-nuclear magnetic resonance revealed intracellular acidification oflas3roots under hypoxia, suggesting that silicate transporter suppression inlas3might arise from an intracellular pH decrease, which is known to be facilitated by a deficiency in ADH activity under anaerobic conditions. This study provides valuable insight into reducing As levels in rice grains.