FLOWERING LOCUS T4delays flowering and decreases floret fertility in barley

Abstract

FLOWERING LOCUS T-like genes (FT-like) control the photoperiodic regulation of flowering in many angiosperm plants. The family of FT-like genes is characterised by extensive gene duplication and subsequent diversification of FT functions which occurred independently in modern angiosperm lineages. In barley, there are 12 known FT-like genes (HvFT) but the function of most of them remains uncharacterised. This study aimed to characterise the role of HvFT4 in flowering time control and development in barley. The overexpression of HvFT4 in the spring cultivar Golden Promise delayed flowering time under long-day conditions. Microscopic dissection of the shoot apical meristem (SAM) revealed that overexpression of HvFT4 specifically delayed spikelet initiation and reduced the number of spikelet primordia and grains per spike. Furthermore, ectopic overexpression of HvFT4 was associated with floret abortion and with the downregulation of the barley MADS-box genes VRN-H1, HvBM3 and HvBM8 which promote floral development. This suggests that HvFT4 functions as a repressor of reproductive development in barley. Unraveling the genetic basis of FT-like genes can contribute to the identification of novel breeding targets to modify reproductive development and thereby spike morphology and grain yield.

Asymmetric expansions of FT and TFL1 lineages characterize differential evolution of the EuPEBP family in the major angiosperm lineages

“…5 ). While [ 28 ] previously identified 12 FT genes in Hordeum vulgare (barley) and Triticum aestivum (bread wheat), our 12 clades are not completely co-equal to these. For instance, the FT13 and FT14 clades that we define for the first time here appear to have been lost from the Triticeae, so do not appear in previous analyses of wheat and barley.…”

“…In eudicots, FT genes are generally present either as a single copy, or as a pair of recent paralogs (e.g. FT/TSF in Arabidopsis), but it is clear that large numbers of FT paralogs are present in the genomes of the Poaceae [ 28 ]. To understand the events that led to this dramatic difference in FT composition, we reconstructed the evolution of the FT lineage in angiosperms, this time including all angiosperm sequences.…”

“…In Brachypodium distyachon , FT9 promotes flowering in response to short-day length [ 30 , 55 ]. In wheat and barley, FT3 is expressed in response to short-day lengths [ 28 ], and it has been identified in barley that it may only promote part of reproductive development, rather than flowering per se [ 56 ]. Barley FT4 represses flowering under long days, which is consistent with its amino acid sequence [ 29 ].…”

“…A similar situation is found in onion, where one FT paralogue promotes flowering, one promotes bulb formation, and another represses bulb formation [ 26 , 27 ]. There has also been an expansion of the FT family in grasses [ 28 ], and these duplicated paralogues play many different roles, including determining floral meristem transition stages [ 29 , 30 ] and the integration of specific environmental signals [ 31 ]. Thus, while EuPEBPs are crucial in the regulation of flowering time, they also have a larger range of regulatory functions in developmental transitions beyond this, e.g.…”

Molecular Insights into Inflorescence Meristem Specification for Yield Potential in Cereal Crops

“…Wheat VRN3 (VERNALIZATION 3) gene encodes an ortholog of FT protein, and mutations of this gene in bread and tetraploid wheat delay the transition to reproductive growth, prolong the duration of spike development, and increases the number of spikelets [70,71]. Overexpression of a barley FT-like gene (HvFT4) specifically delayed spikelet initiation and reduced the number of spikelet primordia and grains per spike [72]. Significantly, both wheat and barley have a major QTL contributing to photoperiodic regulation of flowering called Photoperiod-1 (Ppd-1) [73,74].…”