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Engineering chloroplast development in rice through cellā€specific control of endogenous genetic circuits

Published version
Peer-reviewed

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Authors

Lee, Dongā€Yeon 
Hua, Lei 
Khoshravesh, Roxana 
Giuliani, Rita 
Kumar, Indrajit 

Abstract

Summary: The engineering of C4 photosynthetic activity into the C3 plant rice has the potential to nearly double rice yields. To engineer a twoā€cell photosynthetic system in rice, the rice bundle sheath (BS) must be rewired to enhance photosynthetic capacity. Here, we show that BS chloroplast biogenesis is enhanced when the transcriptional activator, Oryza sativa Cytokinin GATA transcription factor 1 (OsCGA1), is driven by a vascular specific promoter. Ectopic expression of OsCGA1 resulted in increased BS chloroplast planar area and increased expression of photosynthesisā€associated nuclear genes (PhANG), required for the biogenesis of photosynthetically active chloroplasts in BS cells of rice. A further refinement using a DNAse dead Cas9 (dCas9) activation module driven by the same cellā€type specific promoter, directed enhanced chloroplast development of the BS cells when gRNA sequences were delivered by the dCas9 module to the promoter of the endogenous OsCGA1 gene. Single gRNA expression was sufficient to mediate the transactivation of both the endogenous gene and a transgenic GUS reporter fused with OsCGA1 promoter. Our results illustrate the potential for tissueā€specific dCas9ā€activation and the coā€regulation of genes needed for multistep engineering of C4 rice.

Description

Keywords

Original Article, Original Articles, C4 photosynthesis, dCas9ā€mediated transcriptional activation, rice bundle sheath, chloroplast development

Journal Title

Plant Biotechnology Journal

Conference Name

Journal ISSN

1467-7644
1467-7652

Volume Title

Publisher

Sponsorship
Bill and Melinda Gates Foundation (Grant ID#51586, OPP1129902)
NSF (MCBā€1546882)