Total FLC transcript dynamics from divergent paralogue expression explains flowering diversity in Brassica napus

Area of Science:

• Plant genetics
• Agronomy
• Molecular biology

Background:

• Flowering time is crucial for plant adaptation and crop yield.
• FLOWERING LOCUS C (FLC) is a key floral repressor influencing flowering time.
• Brassica napus possesses nine FLC paralogues, complicating the understanding of vernalization response.

Purpose of the Study:

• To investigate how multiple FLC paralogues collectively regulate vernalization requirement in Brassica napus.
• To analyze the dynamics of FLC gene expression in response to cold treatment across different crop types.

Main Methods:

• Transcriptome time-series analysis of Brassica napus spring, winter, semi-winter, and Siberian kale.
• Mathematical modeling to correlate FLC expression dynamics with floral response after vernalization.

Main Results:

• Divergent expression of FLC paralogues was observed due to relaxed selection pressure, leading to variations between paralogues and accessions.
• Total FLC expression dynamics, rather than individual paralogue expression, significantly explains differences in cold requirement among cultivars.
• Multiple FLC paralogues with distinct expression patterns create complex responses to cold, resulting in a broad spectrum of vernalization needs in B. napus.

Conclusions:

• The collective expression of multiple FLC paralogues provides a sophisticated mechanism for regulating vernalization in Brassica napus.
• Different winter rapeseed accessions exhibit diverse strategies for managing cold-induced flowering responses.
• Understanding FLC paralogue systems is key to breeding crops with tailored flowering times and vernalization sensitivities.