Interactions between SQUAMOSA and SHORT VEGETATIVE PHASE MADS-box proteins regulate meristem transitions during wheat spike development. Issue 12 (2nd November 2021)

• Record Type: Journal Article
• Authors: Li, Kun; Debernardi, Juan M; Li, Chengxia; Lin, Huiqiong; Zhang, Chaozhong; Jernstedt, Judy; Korff, Maria von; Zhong, Jinshun; Dubcovsky, Jorge
• Is Part Of: The Plant Cell. Volume 33:Issue 12(2021)
• Page Start: 3621
• Page End: 3644
• Publication Date: 2021-11-02
• DOI: 10.1093/plcell/koab243
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract: Inflorescence architecture is an important determinant of crop productivity. The number of spikelets produced by the wheat inflorescence meristem (IM) before its transition to a terminal spikelet (TS) influences the maximum number of grains per spike. Wheat MADS-box genes VERNALIZATION 1 ( VRN1 ) and FRUITFULL 2 ( FUL2 ) (in the SQUAMOSA -clade) are essential to promote the transition from IM to TS and for spikelet development. Here we show that SQUAMOSA genes contribute to spikelet identity by repressing MADS-box genes VEGETATIVE TO REPRODUCTIVE TRANSITION 2 ( VRT2 ), SHORT VEGETATIVE PHASE 1 ( SVP1 ), and SVP3 in the SVP clade. Constitutive expression of VRT2 resulted in leafy glumes and lemmas, reversion of spikelets to spikes, and downregulation of MADS-box genes involved in floret development, whereas the vrt2 mutant reduced vegetative characteristics in spikelets of squamosa mutants. Interestingly, the vrt2 svp1 mutant showed similar phenotypes to squamosa mutants regarding heading time, plant height, and spikelets per spike, but it exhibited unusual axillary inflorescences in the elongating stem. We propose that SQUAMOSA–SVP interactions are important to promote heading, formation of the TS, and stem elongation during the early reproductive phase, and that downregulation of SVP genes is then necessary for normal spikelet and floral development. Manipulating SVP and SQUAMOSA genes can contribute to engineering spike architectures with improved productivity. Abstract : Functional characterization of developmental genes reveals ways to modify the wheat spike architecture to increase the number of grains and improve productivity.