Bidirectional feedforward regulatory loop of Dicer-like 4 and flavonoids causes floral bicolor patterning in petunia and dahlia
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ABSTRACT: Floral bicolor pigmentation is caused by naturally occurring RNA interference (RNAi) in some cultivars of petunia and dahlia. In both plants, the chalcone synthase gene is highly expressed only in the pigmented region of bicolor petals. However, it remains unknown why RNAi is induced only in the unpigmented region. To elucidate the mechanism of this bicolor pattern formation, we examined the dicing activity of Dicer-like 4 (DCL4), which produces small interfering RNAs essential for RNAi. We showed that the crude extract in the pigmented region inhibits DCL4 activity, but not when flavonoids were depleted from the extract. Moreover, we showed the inhibitory activity was associated with flavonoid aglycons. The in vivo dicing activities were detected in the intact protoplasts prepared from the unpigmented region but not from the pigmented region. These results suggest that in the unpigmented region, flavonoids that inhibit DCL4 are not synthesized, and RNAi is maintained, whereas in the pigmented region, DCL4 (RNAi) is inhibited by flavonoids and anthocyanin biosynthesis is maintained. The results of small RNA-seq analyses of bicolor petals and exogenous flavonoid application experiments support this conclusion. Therefore, a clear bicolor pattern is generated by the bidirectional feedforward mechanism of antagonizing DCL4 and flavonoids.
ORGANISM(S): Dahlia pinnata
PROVIDER: GSE302198 | GEO | 2025/07/09
REPOSITORIES: GEO
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