title: Biochemical and molecular responses underlying differential arsenic tolerance in rice (Oryza sativa L.).
abstract: The arsenic (As) is a toxic element causing major health concern worldwide. Arsenate stress caused no significant reduction in growth parameters and shoot electrolyte leakage but showed increased root arsenate reductase activity along with relatively lower root As content and shoot translocation rate in As-tolerant BRRI 33 than in As-sensitive BRRI 51. It indicates that As inhibition and tolerance mechanisms are driven by root responses. Interestingly, As stress showed consistent decrease in phosphate content and expression of phosphate transporters (OsPT8, OsPT4, OsPHO1;2) under both high and low phosphate conditions in roots of BRRI 33, suggesting that limiting phosphate transport mainly mediated by OsPHO1;2 directs less As accumulation in BRRI 33. Further, BRRI 33 showed simultaneous increase in OsPCS1 (phytochelatin synthase) expression and phytochelatins (PCs) content in roots under As exposure supporting the hypothesis that root As sequestration acts as 'firewall system' in limiting As translocation in shoots. Furthermore, increased CAT, POD, SOD, GR, along with elevated glutathione, methionine, cysteine and proline suggests that strong antioxidant defense plays integral part to As tolerance in BRRI 33. Again, BRRI 33 self-grafts and plants having BRRI 33 rootstock combined with BRRI 51 scion had no adverse effect on morphological parameters but showed reduced As translocation rate, increased root arsenate reductase activity, shoot PC synthesis and root OsPHO1;2 expression due to As stress. It confirms that signal driving As tolerance mechanisms is generated in the roots. These findings can be implemented for As detoxification and As-free transgenic rice production for health safety.
authors.affiliation: Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh.
authors.forename: Most Champa
authors.initials: MC
authors.lastname: Begum
authors.affiliation: Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh.
authors.forename: Mohammad Saiful
authors.initials: MS
authors.lastname: Islam
authors.affiliation: Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh.
authors.forename: Monirul
authors.initials: M
authors.lastname: Islam
authors.affiliation: Bangladesh Council of Scientific and Industrial Research (BCSIR) Laboratories, Rajshahi 6206, Bangladesh.
authors.forename: Ruhul
authors.initials: R
authors.lastname: Amin
authors.affiliation: Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh.
authors.forename: Mohammad Sarwar
authors.initials: MS
authors.lastname: Parvez
authors.affiliation: Department of Botany, University of Rajshahi, Rajshahi 6205, Bangladesh. Electronic address: ahmad.kabir@ru.ac.bd.
authors.forename: Ahmad Humayan
authors.initials: AH
authors.lastname: Kabir
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects* / Q000235:genetics; D000596:Amino Acids / Q000378:metabolism; D000975:Antioxidants / Q000378:metabolism; D053502:Arsenate Reductases / Q000378:metabolism; D001151:Arsenic / Q000633:toxicity*; D001692:Biological Transport / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D012275:Oryza / Q000033:anatomy & histology / Q000187:drug effects / Q000235:genetics* / Q000502:physiology*; D010641:Phenotype; D054811:Phytochelatins / Q000378:metabolism; D018515:Plant Leaves / Q000187:drug effects / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000187:drug effects / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D013054:Spectrophotometry, Atomic
chemical_list: D000596:Amino Acids; D000975:Antioxidants; D010940:Plant Proteins; D054811:Phytochelatins; D053502:Arsenate Reductases; D001151:Arsenic
keywords: Antioxidant activities; As tolerance; OsPCS1; Phosphate transporters; Reciprocal grafting