Abstract
Silicon (Si) has attracted substantial attention because of its beneficial effect on plants during abiotic stress, including stress due to arsenic (As). We here report that priming rice seeds with As and Si together, helped the plant to sustain As stress for longer period. We examined Si induced tolerance against As in rice seedlings at short (7 d) and long (15 d) exposure periods under As((III)) and Si treatments since their germinating stage. Results showed that the expression of As((III)) transporter genes OsLsi1, OsLsi2 and OsLsi6 was more in As((III)) + Si treatment as compared to control and Si treatment, but lower than As((III)) alone treatments. The gene expression was maximum in shoot and root at 15 d over 7 d under both As((III)) and As((III)) + Si treatment, which ultimately leads to decreased accumulation of As in the presence of Si. Morphological characters, antioxidant capacity, oxidative stress marker (MDA), stress modulators (cysteine, proline), and enzymes related with ascorbate-glutathione cycle significantly altered during As((III)) + Si treatment at both exposure periods. Further, macro and micronutrient contents also improved with Si, and differentially regulated 12 key genes (NR, NiR, AMT, NR, GS, GOGAT, PT, PHT1, PHT2, APase, KAT1 and HAK10) related with NPK transport and utilization. Results highlight that Si priming of seeds along with As((III)) influences growth positively of As-stressed rice.