| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 4554706 | Environmental and Experimental Botany | 2011 | 6 Pages |
Arsenate and arsenite sensitivity and arsenate influx tests were conducted for two rice cultivars of different arsenic sensitivity, Azucena and Bala. These were to establish if the mechanism of reduced arsenic sensitivity is achieved through an altered phosphate uptake system, as shown for Holcus lanatus. High phosphate treatments (≥50 μM) provided protection against both arsenate and arsenite. Unlike the H. lanatus tolerance mechanism, in the less sensitive cultivar Bala, arsenate influx did not decrease with phosphate treatment and phosphate transporters appeared to be constitutively upregulated; Vmax for arsenate influx remain similar when Bala was grown in the presence or absence of phosphate (Vmax – 0.90 and 0.63 nmol g−1 f.wt min−1 respectively). Although mean Km appear different, Bala did not show lower affinity to arsenate than Azucena in the absence of phosphate (Km – Azucena, 0.30 mM and Bala, 0.18), while in phosphate treatment, Bala arsenate affinity was half that observed for Azucena (Km – Azucena, 0.14 and Bala, 0.36 mM). These were low compared to a 4 and 6 fold decrease seen for similar studies on H. lanatus in the absence and presence of phosphate. Phosphate-induced arsenic protection was observed but the mechanism does not resemble that of H. lanatus. Alternative mechanisms were discussed.
Research highlights▶ We examine the role of phosphate on rice arsenic sensitivity. ▶ Arsenate and arsenite sensitivity in two differentially sensitive cultivars are shown. ▶ Both cultivars were more sensitive to arsenate than arsenite. ▶ Increasing phosphate led to a reduction in arsenic sensitivity. ▶ Differential sensitivity is not linked to an altered phosphate uptake mechanism.
