Journal
PLANT AND CELL PHYSIOLOGY
Volume 57, Issue 5, Pages 919-932Publisher
OXFORD UNIV PRESS
DOI: 10.1093/pcp/pcw033
Keywords
C-4 rice; Glycine decarboxylase; Oryza sativa (rice); Photorespiration
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Funding
- Bill and Melinda Gates Foundation
- UK Aid
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The glycine decarboxylase complex (GDC) plays a critical role in the photorespiratory C-2 cycle of C-3 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 C-4 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 C-4 evolution. The presence of these two traits important for C-4 photosynthesis and the non-lethal, down-regulation of the photorespiratory C-2 cycle positively contribute to efforts to produce a C-4 rice prototype.
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