Targeted Knockdown ofGDCHin Rice Leads to a Photorespiratory-Deficient Phenotype Useful as a Building Block for C4Rice

Lin, HsiangChun and Karki, Shanta and Coe, Robert A. and Bagha, Shaheen and Khoshravesh, Roxana and Balahadia, C Paolo and Ver Sagun, Julius and Tapia, Ronald and Israel, W Krystler and Montecillo, Florencia and de Luna, Albert and Danila, Florence R and Lazaro, Andrea and Realubit, Czarina M and Acoba, Michelle G and Sage, Tammy L. and von Caemmerer, Susanne and Furbank, Robert T. and Cousins, Asaph B. and Hibberd, Julian M. and Quick, W. Paul and Covshoff, Sarah (2016) Targeted Knockdown ofGDCHin Rice Leads to a Photorespiratory-Deficient Phenotype Useful as a Building Block for C4Rice. Plant and Cell Physiology, 57 (5). pp. 919-932. ISSN 0032-0781

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The glycine decarboxylase complex (GDC) plays a critical role in the photorespiratory C2 cycle of C3 species by recovering carbon following the oxygenation reaction of ribulose-1,5-bisphosphate carboxylase/oxygenase. Loss of GDC from mesophyll cells (MCs) is considered a key early step in the evolution of C4 photosynthesis. To assess the impact of preferentially reducing GDC in rice MCs, we decreased the abundance of OsGDCH (Os10g37180) using an artificial microRNA (amiRNA) driven by a promoter that preferentially drives expression in MCs. GDC H- and P-proteins were undetectable in leaves of gdch lines. Plants exhibited a photorespiratory-deficient phenotype with stunted growth, accelerated leaf senescence, reduced chlorophyll, soluble protein and sugars, and increased glycine accumulation in leaves. Gas exchange measurements indicated an impaired ability to regenerate ribulose 1,5-bisphosphate in photorespiratory conditions. In addition, MCs of gdch lines exhibited a significant reduction in chloroplast area and coverage of the cell wall when grown in air, traits that occur during the later stages of C4 evolution. The presence of these two traits important for C4 photosynthesis and the non-lethal, down-regulation of the photorespiratory C2 cycle positively contribute to efforts to produce a C4 rice prototype.

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Journal Article
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Plant and Cell Physiology
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11 Jan 2022 15:50
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19 Sep 2023 02:44