title: Identification of alternatively spliced transcripts of rice phytochelatin synthase 2 gene OsPCS2 involved in mitigation of cadmium and arsenic stresses.
abstract: The OsPCS2 exhibits root- and shoot-specific differential ratios of alternatively spliced transcripts in indica rice under Cd stress, and plays role in Cd and As stress tolerance and accumulation. Enzymatic activity of phytochelatin synthase (PCS) in plant produces phytochelatins, which help in sequestration of heavy metal(loid)s inside the cell vacuole to alleviate toxicity. Here we report that among the two PCS genes-OsPCS1 and OsPCS2 in indica rice (Oryza sativa) cultivar, the OsPCS2 produces an alternatively spliced OsPCS2b transcript that bears the unusual premature termination codon besides the canonically spliced OsPCS2a transcript. Root- and shoot-specific differential ratios of alternatively spliced OsPCS2a and OsPCS2b transcript expressions were observed under cadmium stress. Saccharomyces cerevisiae cells transformed with OsPCS2a exhibited increased cadmium (Cd) and arsenic (As) tolerance and accumulation, unlike the OsPCS2b transformed yeast cells. An intron-containing hairpin RNA-mediated gene silencing was carried out in endosperm-specific manner for efficient down-regulation of OsPCS genes in rice grains. Analysis of the transgenic rice lines grown under metal(loid) stress revealed almost complete absence of both OsPCS1 and OsPCS2 transcripts in the developing seeds coupled with the significant reduction in the content of Cd (~51%) and As (~35%) in grains compared with the non-transgenic plant. Taken together, the findings indicate towards a crucial role played by the tissue-specific alternative splicing and relative abundance of the OsPCS2 gene during heavy metal(loid) stress mitigation in rice plant.
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.
authors.forename: Natasha
authors.initials: N
authors.lastname: Das
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India.|Plant Molecular Biology and Biotechnology Laboratory, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, VIC, 3010, Australia.
authors.forename: Surajit
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Department of Genetics, Bidhan Chandra Krishi Viswavidyalaya, Mohanpur, 741252, India.
authors.forename: Somnath
authors.initials: S
authors.lastname: Bhattacharyya
authors.affiliation: Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, 721302, India. maitimk@hijli.iitkgp.ernet.in.
authors.forename: Mrinal K
authors.identifier: http://orcid.org/0000-0001-7803-4356
authors.initials: MK
authors.lastname: Maiti
mesh_terms: D017398:Alternative Splicing / Q000187:drug effects*; D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000235:genetics / Q000378:metabolism*; D001151:Arsenic / Q000378:metabolism / Q000633:toxicity*; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D003001:Cloning, Molecular; D018744:DNA, Plant; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D018745:Genome, Plant; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018517:Plant Roots / Q000235:genetics / Q000378:metabolism; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D013312:Stress, Physiological / Q000187:drug effects; D015003:Yeasts
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D002104:Cadmium; D019881:Aminoacyltransferases; C093784:glutathione gamma-glutamylcysteinyltransferase; D001151:Arsenic
keywords: Alternative splicing; Arsenic stress; Cadmium stress; Heterologous expression; OsPCS2; Phytochelatin synthase; RNAi; Transgenic rice