The TCP transcription factor HvTB2 heterodimerizes with VRS5 and controls spike architecture in barley

Abstract

Key message Understanding the molecular network, including protein-protein interactions, of VRS5 provide new routes towards the identification of other key regulators of plant architecture in barley. Abstract The TCP transcriptional regulator TEOSINTE BRANCHED 1 (TB1) is a key regulator of plant architecture. In barley, an important cereal crop, HvTB1 (also referred to as VULGARE SIX-ROWED spike (VRS) 5), inhibits the outgrowth of side shoots, or tillers, and grains. Despite its key role in barley development, there is limited knowledge on the molecular network that is utilized by VRS5. In this work, we performed protein–protein interaction studies of VRS5. Our analysis shows that VRS5 potentially interacts with a diverse set of proteins, including other class II TCP’s, NF-Y TF, but also chromatin remodelers. Zooming in on the interaction capacity of VRS5 with other TCP TFs shows that VRS5 preferably interacts with other class II TCP TFs in the TB1 clade. Induced mutagenesis through CRISPR–Cas of one of the putative VRS5 interactors, HvTB2 (also referred to as COMPOSITUM 1 and BRANCHED AND INDETERMINATE SPIKELET 1), resulted in plants that have lost their characteristic unbranched spike architecture. More specifically, hvtb2 mutants exhibited branches arising at the main spike, suggesting that HvTB2 acts as inhibitor of branching. Our protein–protein interaction studies of VRS5 resulted in the identification of HvTB2 as putative interactor of VRS5, another key regulator of spike architecture in barley. The study presented here provides a first step to underpin the protein–protein interactome of VRS5 and to identify other, yet unknown, key regulators of barley plant architecture.

Flowering time genes branching out

“…In addition, TCPs are implicated in different hormonal signalling pathways ( Nicolas and Cubas, 2016a ). TCPs have also been shown to be involved in developmental processes such as flowering time, whole-plant and inflorescence architecture ( Ramsay et al , 2011 ; Bai et al , 2012 ; S. Wang et al ., 2015 ; Nicolas and Cubas, 2016b ; Dixon et al , 2018 ; de Souza Moraes et al , 2022 ), and fertility ( Jin et al , 2011 ; Jiao et al , 2018 ; Gladman et al , 2019 ; de Souza Moraes et al , 2022 ). TCP members are additionally engaged in drought tolerance ( Ding et al , 2019 ; Urano et al , 2022 ; Gull et al , 2023 ; Jiao et al , 2023 ) and plant defence ( Kim et al , 2014 ; X. Wang et al ., 2015 ; Bao et al , 2019 ; Wang et al ., 2019 ).…”

Advances in Research on the Regulation of Floral Development by CYC-like Genes

“…The TCP family members contain a highly conserved TCP domain, which forms a basic helix–loop–helix (bHLH) structure associated with DNA binding and protein dimerization [ 10 , 11 ]. TB1 is a major regulator of stem and lateral bud growth and the male flower formation of maize, rice, wheat, and other crops [ 12 , 13 , 14 ], whereas CYC controls the floral dorsal organ characteristics in snapdragon [ 1 , 15 ], and both PCF1 and PCF2 bind to the promoter of PROLIFERATING CELL NUCLEAR ANTIGEN (PCNA), which is crucial for DNA replication and repair, chromatin structure maintenance, chromosome isolation, and the cell cycle in rice [ 3 ]. According to their different domains, the members of the TCP family have been divided into the following two categories: TCP-P and TCP-C [ 16 , 17 , 18 ].…”