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Gann PJI, Dharwadker D, Cherati SR, Vinzant K, Khodakovskaya M, Srivastava V. Targeted mutagenesis of the vacuolar H + translocating pyrophosphatase gene reduces grain chalkiness in rice. Plant J 2023; 115:1261-1276. [PMID: 37256847 DOI: 10.1111/tpj.16317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 05/12/2023] [Accepted: 05/18/2023] [Indexed: 06/02/2023]
Abstract
Grain chalkiness is a major concern in rice production because it impacts milling yield and cooking quality, eventually reducing market value of the rice. A gene encoding vacuolar H+ translocating pyrophosphatase (V-PPase) is a major quantitative trait locus in indica rice, controlling grain chalkiness. Higher transcriptional activity of this gene is associated with increased chalk content. However, whether the suppression of V-PPase could reduce chalkiness is not clear. Furthermore, natural variation in the chalkiness of japonica rice has not been linked with V-PPase. Here, we describe promoter targeting of the japonica V-PPase allele that led to reduced grain chalkiness and the development of more translucent grains. Disruption of a putative GATA element by clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 suppressed V-PPase activity, reduced grain chalkiness and impacted post-germination growth that could be rescued by the exogenous supply of sucrose. The mature grains of the targeted lines showed a much lower percentage of large or medium chalk. Interestingly, the targeted lines developed a significantly lower chalk under heat stress, a major inducer of grain chalk. Metabolomic analysis showed that pathways related to starch and sugar metabolism were affected in the developing grains of the targeted lines that correlated with higher inorganic pyrophosphate and starch contents and upregulation of starch biosynthesis genes. In summary, we show a biotechnology approach of reducing grain chalkiness in rice by downregulating the transcriptional activity of V-PPase that presumably leads to altered metabolic rates, including starch biosynthesis, resulting in more compact packing of starch granules and formation of translucent rice grains.
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Affiliation(s)
- Peter James Icalia Gann
- Cell and Molecular Biology Program, University of Arkansas, 115 Plant Science Building, Fayetteville, AR, 72701, USA
- Department of Crop, Soil and Environmental Sciences, University of Arkansas Division of Agriculture, 115 Plant Science Building, Fayetteville, AR, 72701, USA
| | - Dominic Dharwadker
- Department of Chemistry and Biochemistry, University of Arkansas, 119 Chemistry Building, Fayetteville, West Maple Street, AR, 72701, USA
| | - Sajedeh Rezaei Cherati
- Department of Biology, University of Arkansas Little Rock, 2801 S University Avenue, Little Rock, AR, 727704, USA
| | - Kari Vinzant
- Department of Biology, University of Arkansas Little Rock, 2801 S University Avenue, Little Rock, AR, 727704, USA
| | - Mariya Khodakovskaya
- Department of Biology, University of Arkansas Little Rock, 2801 S University Avenue, Little Rock, AR, 727704, USA
| | - Vibha Srivastava
- Cell and Molecular Biology Program, University of Arkansas, 115 Plant Science Building, Fayetteville, AR, 72701, USA
- Department of Crop, Soil and Environmental Sciences, University of Arkansas Division of Agriculture, 115 Plant Science Building, Fayetteville, AR, 72701, USA
- Department of Horticulture, University of Arkansas Division of Agriculture, 315 Plant Science Building, Fayetteville, AR, 72701, USA
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