US EPA

1519073 

Journal Article 

Arsenite elicits anomalous sulfur starvation responses in barley 

Reid, R; Gridley, K; Kawamata, Y; Zhu, Y 

2013 

1 

Plant Physiology
ISSN: 0032-0889
EISSN: 1532-2548 

162 

1 

401-409 

English 

23482871 

10.1104/pp.113.216937 

WOS:000318547900030 

https://academic.oup.com/plphys/article/162/1/401-409/6110872
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Treatment of barley (Hordeum vulgare) seedlings with arsenite (AsIII) rapidly induced physiological and transcriptional changes characteristic of S deficiency, even in plants replete with S. AsIII and S deficiency induced 5 - 20 fold increases in the three genes responsible for sulfate reduction. Both treatments also caused upregulation of a sulfate transporter, but only in the case of S deficiency was there an increase in sulfate influx. Longer term changes included reduction in transfer of S from roots to shoots, and an increase in root growth relative to shoot growth. Genes involved in complexation and compartmentation of As were upregulated by AsIII but not by S-deficiency. The rate at which As accumulated appeared to be controlled by the rate of thiol synthesis. Over a range of AsIII concentrations and growth periods, the ratio of thiols to As was always close to 3:1, which is consistent with the formation of a stable GS3:AsIII complex.The greater toxicity of As under S-limiting conditions is likely to be due to an intensification of S deficiency as a result of thiol synthesis rather than to a direct toxicity to metabolism. Since influx of AsIII was nearly 20-fold faster than the rate of synthesis of thiols, it is questionable whether this complexation strategy can be effective in preventing As toxicity unless As uptake becomes limited by diffusive resistances in the rhizosphere.