FLOWERING LOCUS T3 Controls Spikelet Initiation But Not Floral Development

Area of Science:

• Plant genetics and molecular biology
• Reproductive development in angiosperms
• Crop science and yield improvement

Background:

• FLOWERING LOCUS T (FT)-like genes are crucial for plant reproduction, often undergoing duplication and functional divergence.
• Barley (Hordeum vulgare) possesses multiple FT-like genes, but their specific roles in development remain largely uncharacterized.
• Understanding these genes is key to improving crop adaptation and yield.

Purpose of the Study:

• To elucidate the function of the HvFT3 gene in barley's vegetative and reproductive development.
• To investigate HvFT3's role in spikelet initiation, floral development, and its interaction with photoperiod and vernalization pathways.
• To identify downstream targets of HvFT3 in barley shoot apex development.

Main Methods:

• Overexpression of the HvFT3 gene in spring barley.
• Analysis of a nonfunctional HvFT3 allele.
• Transcriptome analysis of developing main shoot apices in transgenic barley lines.
• Gene expression analysis of VERNALIZATION1 (VRN-H1) and key developmental genes.

Main Results:

• HvFT3 overexpression accelerated spikelet primordia initiation and early reproductive development, independent of photoperiod.
• HvFT3 did not accelerate floral development, with inflorescences aborting under short days, indicating a role in spikelet initiation only.
• HvFT3 up-regulated VERNALIZATION1 (VRN-H1) alleles in nonvernalized plants, overriding vernalization pathway repression.
• Transcriptome analysis revealed HvFT3 influences genes related to hormone synthesis/response, floral homeotics, and barley row-type genes (VRS1, VRS4).

Conclusions:

• HvFT3 specifically controls barley spikelet initiation, independent of photoperiod and dominant over vernalization pathways.
• HvFT3's function in spikelet initiation is distinct from its role in floral development.
• Modulating HvFT3 and other FT-like genes offers potential for tailoring preanthesis development for improved crop adaptation and yield.