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Choi S, Prabhakar PK, Chowdhury R, Pendergast TH, Urbanowicz BR, Maranas C, Devos KM. A single amino acid change led to structural and functional differentiation of PvHd1 to control flowering in switchgrass. J Exp Bot 2023; 74:5532-5546. [PMID: 37402629 PMCID: PMC10540729 DOI: 10.1093/jxb/erad255] [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] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 07/03/2023] [Indexed: 07/06/2023]
Abstract
Switchgrass, a forage and bioenergy crop, occurs as two main ecotypes with different but overlapping ranges of adaptation. The two ecotypes differ in a range of characteristics, including flowering time. Flowering time determines the duration of vegetative development and therefore biomass accumulation, a key trait in bioenergy crops. No causal variants for flowering time differences between switchgrass ecotypes have, as yet, been identified. In this study, we mapped a robust flowering time quantitative trait locus (QTL) on chromosome 4K in a biparental F2 population and characterized the flowering-associated transcription factor gene PvHd1, an ortholog of CONSTANS in Arabidopsis and Heading date 1 in rice, as the underlying causal gene. Protein modeling predicted that a serine to glycine substitution at position 35 (p.S35G) in B-Box domain 1 greatly altered the global structure of the PvHd1 protein. The predicted variation in protein compactness was supported in vitro by a 4 °C shift in denaturation temperature. Overexpressing the PvHd1-p.35S allele in a late-flowering CONSTANS-null Arabidopsis mutant rescued earlier flowering, whereas PvHd1-p.35G had a reduced ability to promote flowering, demonstrating that the structural variation led to functional divergence. Our findings provide us with a tool to manipulate the timing of floral transition in switchgrass cultivars and, potentially, expand their cultivation range.
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Affiliation(s)
- Soyeon Choi
- Department of Genetics, University of Georgia, Athens, GA 30602, USA
| | - Pradeep K Prabhakar
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Ratul Chowdhury
- Chemical Engineering, Penn State University, State College, PA 16801, USA
| | - Thomas H Pendergast
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
- Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30602, USA
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Athens, GA 30602, USA
| | - Breeanna R Urbanowicz
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
| | - Costas Maranas
- Chemical Engineering, Penn State University, State College, PA 16801, USA
| | - Katrien M Devos
- Department of Plant Biology, University of Georgia, Athens, GA 30602, USA
- Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30602, USA
- Institute of Plant Breeding, Genetics and Genomics, University of Georgia, Athens, GA 30602, USA
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