A single amino acid change led to structural and functional differentiation of PvHd1 to control flowering in switchgrass

Soyeon Choi, Pradeep K. Prabhakar, Ratul Chowdhury, Thomas H. Pendergast, Breeanna R. Urbanowicz, Costas Maranas, Katrien M. Devos

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)5532-5546
Number of pages15
JournalJournal of experimental botany
Issue number18
StatePublished - Sep 29 2023

All Science Journal Classification (ASJC) codes

  • Physiology
  • Plant Science

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