title: Molecular and Functional Characterization of GR2-R1 Event Based Backcross Derived Lines of Golden Rice in the Genetic Background of a Mega Rice Variety Swarna.
abstract: Homozygous Golden Rice lines developed in the background of Swarna through marker assisted backcross breeding (MABB) using transgenic GR2-R1 event as a donor for the provitamin A trait have high levels of provitamin A (up to 20 ppm) but are dwarf with pale green leaves and drastically reduced panicle size, grain number and yield as compared to the recurrent parent, Swarna. In this study, we carried out detailed morphological, biochemical and molecular characterization of these lines in a quest to identify the probable reasons for their abnormal phenotype. Nucleotide blast analysis with the primer sequences used to amplify the transgene revealed that the integration of transgene disrupted the native OsAux1 gene, which codes for an auxin transmembrane transporter protein. Real time expression analysis of the transgenes (ZmPsy and CrtI) driven by endosperm-specific promoter revealed the leaky expression of the transgene in the vegetative tissues. We propose that the disruption of OsAux1 disturbed the fine balance of plant growth regulators viz., auxins, gibberellic acid and abscisic acid, leading to the abnormalities in the growth and development of the lines homozygous for the transgene. The study demonstrates the conserved roles of OsAux1 gene in rice and Arabidopsis.
authors.affiliation: Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, Delhi, India.
authors.forename: Haritha
authors.initials: H
authors.lastname: Bollinedi
authors.affiliation: Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, Delhi, India.
authors.forename: Gopala Krishnan
authors.initials: GK
authors.lastname: S
authors.affiliation: Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, Delhi, India.
authors.forename: Kumble Vinod
authors.initials: KV
authors.lastname: Prabhu
authors.affiliation: ICAR-National Research Centre on Plant Biotechnology, Pusa Campus, New Delhi, Delhi, India.
authors.forename: Nagendra Kumar
authors.initials: NK
authors.lastname: Singh
authors.affiliation: Department of Plant Molecular Biology, University of Delhi, South Campus, New Delhi, Delhi, India.
authors.forename: Sushma
authors.initials: S
authors.lastname: Mishra
authors.affiliation: Department of Plant Molecular Biology, University of Delhi, South Campus, New Delhi, Delhi, India.
authors.forename: Jitendra P
authors.initials: JP
authors.lastname: Khurana
authors.affiliation: Division of Genetics, ICAR-Indian Agricultural Research Institute, New Delhi, Delhi, India.
authors.forename: Ashok Kumar
authors.initials: AK
authors.lastname: Singh
mesh_terms: D001947:Breeding; D002734:Chlorophyll; D003433:Crosses, Genetic; D000068617:Genetic Background; D018525:Germination; D006720:Homozygote; D012275:Oryza / Q000235:genetics*; D010641:Phenotype; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic; D059467:Transcriptome; D019076:Transgenes; D015053:Zygote
chemical_list: D002734:Chlorophyll