Increased and ectopic expression of Triticum polonicum VRT-A2 underlies elongated glumes and grains in hexaploid wheat in a dosage-dependent manner

Flower development is a major determinant of yield in crops. In wheat, natural variation for the size of spikelet and floral organs is particularly evident in Triticum polonicum, a tetraploid subspecies of wheat with long glumes, lemmas, and grains. Using map-based cloning, we identified VRT2, a MADS-box transcription factor belonging to the SVP family, as the gene underlying the P1 locus. The causal P1 mutation is a sequence substitution in intron-1 that results in both increased and ectopic expression of the T. polonicum VRT-A2 allele. Based on allelic variation studies, we propose that the intron-1 mutation in VRT-A2 is the unique T. polonicum species defining polymorphism, which was later introduced into hexaploid wheat via natural hybridizations. Near-isogenic lines differing for the T. polonicum long-glume (P1) locus revealed a gradient effect of P1 across florets. Transgenic lines of hexaploid wheat carrying the T. polonicum VRT-A2 allele show that expression levels of VRT-A2 are highly correlated with spike, glume, grain, and floral organ length. These results highlight how changes in expression profiles, through variation in cis-regulation, can impact on agronomic traits in a dosage-dependent manner in polyploid crops.

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  • Name: Adamski, Nikolai M., Type: Corresponding Author,
  • Name: Simmonds, James, Type: Author,
  • Name: Brinton, Jemima F., Type: Author,
  • Name: Backhaus, Anna E., Type: Author,
  • Name: Chen, Yi, Type: Author,
  • Name: Smedley, Mark, Type: Author,
  • Name: Hayta, Sadiye, Type: Author,
  • Name: Florio, Tobin, Type: Author,
  • Name: Crane, Pamela, Type: Author,
  • Name: Scott, Peter, Type: Author,
  • Name: Pieri, Alice, Type: Author,
  • Name: Hall, Olyvia, Type: Author,
  • Name: Barclay, J. Elaine, Type: Author,
  • Name: Clayton, Myles, Type: Author,
  • Name: Doonan, John H., Type: Author,
  • Name: Nibau, Candida, Type: Author,
  • Name: Uauy, Cristobal, Type: Author,
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Article License Type cc-by-nc
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DFW Organisation JIC
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DOI 10.1101/2020.11.09.375154
Date Last Updated 2020-11-17T13:36:19.224217
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