Radish, a member of the Brassicaceae family, has been a popular root vegetable grown for centuries. However, the timing of radish flowering is crucial for successful cultivation. Radish plants that flower too early may not produce a substantial yield of roots, while late-flowering plants can lead to overgrowth and lower-quality roots. Yuki Mitsui, from Tokyo University of Agriculture, and colleagues have recently found that complex interactions among replicated FLC genes determine the flowering time of radishes.
Researchers used RNA sequencing analysis to examine the regulatory roles and interactions of radish FLOWERING LOCUS C (RsFLC) genes, the main flowering repressor candidates, and other flowering-related genes. They found that some genes related to flowering, cool temperature and day length sensing, and other flowering pathways were differentially expressed in early-bolting and late-bolting radish cultivars under different flowering-inducing cold conditions.
Among the flowering integrator genes, the four RsSOC1 copies, which are flowering inducers, were downregulated. The three RsFLC copies, which are flowering repressors, were upregulated in the late bolting cultivar compared to the early bolting cultivar in flowering-inducing cold conditions.
The scientists also looked at how some small pieces of DNA in two important genes (RsFLC1 and RsFLC2) could affect when radish plants flower. They found that adding these pieces of DNA to the genes can make the plants flower later than usual. They also found that one of these pieces of DNA in RsFLC2 affects not only that gene, but all three RsFLC genes, which means that controlling when radishes flower is complex and involves lots of different genes working together. Mitsui and colleagues write:
Our results suggest that the flowering time of radish is determined by epistatic interactions among replicated FLC genes. This provides a unique system for investigating regulatory interactions among evolutionary divergent loci originating from orthologous genomes. As the same RsFLC1 and RsFLC2 insertion alleles are found in several radish cultivars, our results will be helpful for further breeding improvements.Mitsui et al. 2023
READ THE ARTICLE
Mitsui Y., Yokoyama H., Nakaegawa W., Tanaka K., Komatsu K., Koizuka N., Okuzaki A., Matsumoto T., Takahara M. and Tabei Y. (2023) “Epistatic interactions among multiple copies of FLC genes with naturally occurring insertions correlate with flowering time variation in radish” AoB PLANTS, 15(2), p. lac066. Available at: https://doi.org/10.1093/aobpla/plac066