The role of nodes in arsenic storage and distribution in rice.
Knowledge of arsenic (As) accumulation in rice (Oryza sativa L.) is important for minimizing As transfer to the food chain. The aim of this study was to investigate the role of rice nodes in As storage and distribution. Synchrotron μX-ray fluorescence (μ-XRF) was used to map As distribution in the top node and internode of a lsi2 mutant defective in silicon/arsenite efflux carrier and its wild-type (WT) grown in soil. Lsi2 expression in different tissues during grain filling was investigated by quantitative RT-PCR. Arsenite or dimethylarsinic acid (DMA) was supplied to excised panicles to investigate the roles of Lsi2 and phytochelatins (PC) in As distribution. μ-XRF mapping revealed As storage in the phloem of different vascular bundles in the top node and internode. Soil-grown plants of lsi2 had markedly decreased As accumulation in the phloem compared with the WT. Lsi2 was strongly expressed, not only in the roots but also in the nodes. When excised panicles were exposed to As(III), the lsi2 mutant distributed more As to the node and flag leaf but less As to the grain compared with the WT, while there was no significant difference in DMA distribution. Inhibition of PC synthesis by l-buthionine-sulphoximine decreased As(III) deposition in the top node but increased As accumulation in the grain and flag leaf. The results suggest that rice nodes serve as a filter restricting As(III) distribution to the grain. Furthermore, Lsi2 plays a role in As(III) distribution in rice nodes and phytochelatins are important compounds for As(III) storage in the nodes.
Department of Sustainable Soils and Grassland Systems, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
Yi
Y
Chen
School of Materials, University of Manchester, Manchester M13 9PL, UK.
Katie L
KL
Moore
Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
Anthony J
AJ
Miller
Department of Sustainable Soils and Grassland Systems, Rothamsted Research, Harpenden, Hertfordshire AL5 2JQ, UK.
Steve P
SP
McGrath
Institute of Plant Science and Resources, Okayama University, Chuo 2-20-1, Kurashiki 710-0046, Japan.
Jian Feng
JF
Ma
State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, China fangjie.zhao@njau.edu.cn.
Fang-Jie
FJ
Zhao
D001151:Arsenic / Q000378:metabolism*; D001692:Biological Transport / Q000187:drug effects; D019328:Buthionine Sulfoximine / Q000494:pharmacology; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D009154:Mutation / Q000235:genetics; D009928:Organ Specificity / Q000187:drug effects; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018547:Plant Stems / Q000187:drug effects / Q000378:metabolism*; D013052:Spectrometry, X-Ray Emission
D010940:Plant Proteins; D019328:Buthionine Sulfoximine; D001151:Arsenic
Arsenic; Lsi2; dimethylarsinic acid; node; rice; synchrotron μX-ray fluorescence.