TEOSINTE BRANCHED1 and Wheat Inflorescence Architecture

Dixon et al. (2018) investigate the regulation of wheat inflorescence architecture by TEOSINTE BRANCHED1. Plant Cell https://doi.org/10.1105/tpc.17.00961

Background: Grass inflorescences are composed of many seed-producing flowers (or florets) that are arranged on branches called spikelets. The number and arrangement of spikelets that form on an inflorescence, and the rate of inflorescence development, contribute significantly to the grain yield of major cereals (including wheat, rice and maize). However, while bread wheat (Triticum aestivum L.) provides 20% of the world’s calories and protein, very little is known about the genes that control its inflorescence development. To identify genes that regulate spikelet development in wheat, we investigated a trait known as paired spikelets, which are characterized by the formation of two spikelets at a position where usually only one spikelet forms.

Question: The aim of our study was to investigate genes that regulate inflorescence development in bread wheat, and to increase our understanding of the molecular processes involved in generating the different morphologies of cereal grass inflorescences.

Findings: We demonstrated that TEOSINTE BRANCHED1 (TB1) is a gene that regulates inflorescence architecture and development of bread wheat in a dosage-dependent manner. We show that increased levels of TB1 promote development of paired spikelets in a process that involves an interaction with FLOWERING LOCUS T (FT) protein (a key regulator of flowering), and reduced expression of meristem identity genes during early inflorescence development. We have also found that variant alleles of TB1 contribute to diversity for inflorescence architecture in cultivated wheat.

Next Steps: An important step now will be to determine the ideal combination of TB1 and FT alleles (alternative forms of these genes) that could be used to optimize inflorescence development and grain production in bread wheat, and to investigate the contribution of variant TB1 alleles to other agronomically important traits such as tiller number, plant height, and floret fertility.

Laura E. Dixon, Julian R. Greenwood, Stefano Bencivenga, Peng Zhang, James Cockram, Gregory Mellers, Kerrie Ramm, Colin Cavanagh, Steve M. Swain, Scott A. Boden. (2018). TEOSINTE BRANCHED1 Regulates Inflorescence Architecture and Development in Bread Wheat (Triticum aestivum). Plant Cell 30: 563-581; DOI: https://doi.org/10.1105/tpc.17.00961.