Mechanisms of heavy metal accumulation in rice
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- 英文论文题名：Mechanisms of heavy metal accumulation in rice
- 论文作者：Fang-Jie Zhao
- 英文论文作者：Fang-Jie Zhao ; State Key Laboratory of Crop Genetics and Germplasm Enhancement ; College of Resources and Environmental Sciences ; Nanjing Agricultural University
- 年：2016
- 作者机构：State Key Laboratory of Crop Genetics and Germplasm Enhancement,College of Resources and Environmental Sciences,Nanjing Agricultural University;
- 英文论文关键词：arsenic ; cadmium ; food safety ; heavy metal contamination ; rice
- 会议召开时间：2016-10-09
- 会议录名称：2016年全国植物生物学大会摘要集
- 语种：英文
- 分类号：X56;S511
- 学会代码：ZGZO
- 会议名称：2016年全国植物生物学大会
- 会议地点：中国湖北武汉
- 主办单位：中国遗传学会、中国细胞生物学学会、中国植物学会、中国植物生理与植物分子生物学学会、中国作物学会
- 学会名称：中国植物学会
- 页数：1
- 文件大小：840k
- 原文格式：D
- 会议级别：全国
摘要
Approximately one fifth of the agricultural soils in China is contaminated,mainly by heavy metals or metalloids such as cadmium(Cd) and arsenic(As),which are the class-one carcinogens. Rice produced in some areas of southern China often exceeds the maximum permissible limits of Cd and As,posing a significant risk to food safety. Contamination in soil and irrigation water,soil acidification and growing cultivars with a high accumulation ability are the main reasons for high levels of heavy metals in rice grain. There are large genetic variations among rice cultivars and germplasms in both grain Cd and As concentrations. Os HMA3 is a Cd transporter on the tonoplast functioning to sequester Cd into the vacuole of rice roots. We have recently identified a new loss-of-function allele of Os HMA3 associated with high Cd accumulation in rice grain. This allele has a predicted amino acid mutation at the 380 th position from Ser to Arg and is present only in some Japonica cultivars. Cultivars possessing this allele have markedly increased root to shoot translocation of Cd. Paddy rice also accumulates As because of the elevated availability of As in flooded paddy soil. We have previously discovered that arsenite is taken up by silicon transporters in rice. In contrast,arsenate is taken up by phosphate transporters. Plants are able to reduce arsenate to arsenite efficiently and to extrude arsenite to the external medium,thus avoiding excessive buildup of As in plant tissues. We have recently characterized two arsenate reductases in rice(Os HAC1;1 and Os HAC1;2). Mutations in the two genes result in decreased arsenate reduction and arsenite efflux,and increased As accumulation in rice plants. Overexpression of either gene increases arsenate reduction and arsenite efflux,leading to lower As accumulation in rice plants and increased tolerance to arsenate.
Approximately one fifth of the agricultural soils in China is contaminated,mainly by heavy metals or metalloids such as cadmium(Cd) and arsenic(As),which are the class-one carcinogens. Rice produced in some areas of southern China often exceeds the maximum permissible limits of Cd and As,posing a significant risk to food safety. Contamination in soil and irrigation water,soil acidification and growing cultivars with a high accumulation ability are the main reasons for high levels of heavy metals in rice grain. There are large genetic variations among rice cultivars and germplasms in both grain Cd and As concentrations. Os HMA3 is a Cd transporter on the tonoplast functioning to sequester Cd into the vacuole of rice roots. We have recently identified a new loss-of-function allele of Os HMA3 associated with high Cd accumulation in rice grain. This allele has a predicted amino acid mutation at the 380 th position from Ser to Arg and is present only in some Japonica cultivars. Cultivars possessing this allele have markedly increased root to shoot translocation of Cd. Paddy rice also accumulates As because of the elevated availability of As in flooded paddy soil. We have previously discovered that arsenite is taken up by silicon transporters in rice. In contrast,arsenate is taken up by phosphate transporters. Plants are able to reduce arsenate to arsenite efficiently and to extrude arsenite to the external medium,thus avoiding excessive buildup of As in plant tissues. We have recently characterized two arsenate reductases in rice(Os HAC1;1 and Os HAC1;2). Mutations in the two genes result in decreased arsenate reduction and arsenite efflux,and increased As accumulation in rice plants. Overexpression of either gene increases arsenate reduction and arsenite efflux,leading to lower As accumulation in rice plants and increased tolerance to arsenate.
Approximately one fifth of the agricultural soils in China is contaminated,mainly by heavy metals or metalloids such as cadmium(Cd) and arsenic(As),which are the class-one carcinogens. Rice produced in some areas of southern China often exceeds the maximum permissible limits of Cd and As,posing a significant risk to food safety. Contamination in soil and irrigation water,soil acidification and growing cultivars with a high accumulation ability are the main reasons for high levels of heavy metals in rice grain. There are large genetic variations among rice cultivars and germplasms in both grain Cd and As concentrations. Os HMA3 is a Cd transporter on the tonoplast functioning to sequester Cd into the vacuole of rice roots. We have recently identified a new loss-of-function allele of Os HMA3 associated with high Cd accumulation in rice grain. This allele has a predicted amino acid mutation at the 380 th position from Ser to Arg and is present only in some Japonica cultivars. Cultivars possessing this allele have markedly increased root to shoot translocation of Cd. Paddy rice also accumulates As because of the elevated availability of As in flooded paddy soil. We have previously discovered that arsenite is taken up by silicon transporters in rice. In contrast,arsenate is taken up by phosphate transporters. Plants are able to reduce arsenate to arsenite efficiently and to extrude arsenite to the external medium,thus avoiding excessive buildup of As in plant tissues. We have recently characterized two arsenate reductases in rice(Os HAC1;1 and Os HAC1;2). Mutations in the two genes result in decreased arsenate reduction and arsenite efflux,and increased As accumulation in rice plants. Overexpression of either gene increases arsenate reduction and arsenite efflux,leading to lower As accumulation in rice plants and increased tolerance to arsenate.
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