Original Article

Planta

, Volume 223, Issue 4, pp 627-636

Light-regulated overexpression of an Arabidopsis phytochrome A gene in rice alters plant architecture and increases grain yield

  • Ajay K. GargAffiliated withDepartment of Molecular Biology and Genetics, Cornell University
  • , Ruairidh J. H. SawersAffiliated withBoyce Thompson Institute, Cornell University
  • , Haiyang WangAffiliated withBoyce Thompson Institute, Cornell University
  • , Ju-Kon KimAffiliated withDivision of Bioscience and Bioinformatics, Myongji University
  • , Joseph M. WalkerAffiliated withDepartment of Genetics, University of Wisconsin-Madison
  • , Thomas P. BrutnellAffiliated withBoyce Thompson Institute, Cornell University
  • , Mandayam V. ParthasarathyAffiliated withDepartment of Plant Biology, Cornell University
  • , Richard D. VierstraAffiliated withDepartment of Genetics, University of Wisconsin-Madison
  • , Ray J. WuAffiliated withDepartment of Molecular Biology and Genetics, Cornell University Email author 

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Abstract

The phytochromes are a family of red/far-red light absorbing photoreceptors that control plant developmental and metabolic processes in response to changes in the light environment. We report here the overexpression of Arabidopsis thaliana PHYTOCHROME A (PHYA) gene in a commercially important indica rice variety (Oryza sativa L. Pusa Basmati-1). The expression of the transgene was driven by the light-regulated and tissue-specific rice rbcS promoter. Several independent homozygous sixth generation (T5) transgenic lines were characterized and shown to accumulate relatively high levels of PHYA protein in the light. Under both far-red and red light, PHYA-overexpressing lines showed inhibition of the coleoptile extension in comparison to non-transgenic seedlings. Furthermore, compared with non-transgenic rice plants, mature transgenic plants showed significant reduction in plant height, internode length and internode diameter (including differences in cell size and number), and produced an increased number of panicles per plant. Under greenhouse conditions, rice grain yield was 6–21% higher in three PHYA-overexpressing lines than in non-transgenic plants. These results demonstrate the potential of manipulating light signal-transduction pathways to minimize the problems of lodging in basmati/aromatic rice and to enhance grain productivity.

Keywords

Arabidopsis PHYA gene Grain yield Plant architecture Phytochrome A Rice rbcS promoter Transgenic rice