Natural variation in FLOWERING LOCUS C and FLOWERING LOCUS M underlies the weak temperature sensitivity of the Arabidopsis accession Ellershausen
2025
Zeeshan Nasim | Nouroz Karim | Hendry Susila | Ji Hoon Ahn
Natural variants of key floral regulator genes underly the adaptation of plant populations to diverse environmental conditions. We identified Ellershausen (El-0) as an early flowering Arabidopsis (Arabidopsis thaliana) accession with decreased sensitivity to changes in temperature and photoperiod. Expression levels of FLOWERING LOCUS M (FLM), including its major splice variants FLM-β and FLM-δ, were dramatically lower in El-0 than in Col-0 or Killean (Kil-0) accessions at different temperatures. The first intron of FLMEl−0 contains a ∼5.7-kb LINE transposon insertion, as in Kil-0, together with several single-nucleotide polymorphisms. However, El-0 flowered earlier than Kil-0 at 23 °C or 16 °C under long-day conditions and at 23°C under short-day conditions. Introducing a genomic copy of FLMCol−0 into El-0 moderately delayed flowering, suggesting that an additional player(s) is involved in the temperature-insensitive flowering of El-0. Accordingly, expression levels of FLOWERING LOCUS C (FLC) and MADS AFFECTING FLOWERING 5 (MAF5) were lower in El-0. Genome resequencing data revealed polymorphisms including deletions in FLCEl−0 and MAF5El−0. β-Glucuronidase activity was weaker in pFLCCol−0:gFLCEl−0-GUS transgenic seedlings than in pFLCCol−0:gFLCCol−0-GUS seedlings, suggesting that polymorphisms in FLCEl−0 result in lower FLCEl−0 transcript levels. Consistent with low FLC expression levels, El-0 plants did not flower earlier following vernalization. Our results suggest that natural variants of these repressor genes in El-0 may facilitate successful adaptation to relatively cooler climates.
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