Project description: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.
Project description:Transcript profiles of Laccaria bicolor S238N mycelium on various media were analyzed. The array probes were designed from gene models taken from the Joint Genome Institute (JGI, department of energy) Laccaria bicolor genome sequence version 1. One goal was to evaluate the effect of nutrient deprivation on the transcriptome of Laccaria bicolor.
Project description:Transcript profiles of Laccaria bicolor S238N mycelium on various media were analyzed. The array probes were designed from gene models taken from the Joint Genome Institute (JGI, department of energy) Laccaria bicolor genome sequence version 1. One goal was to evaluate the effect of nutrient deprivation on the transcriptome of Laccaria bicolor. We performed 15 hybridizations (Roche-NimbleGen) with samples derived from Laccaria bicolor free-living mycelium grown on MMN medium, on MMN with a 10 times reduction in all major macro-elements, on MMN with a 10 times reduction in the quantity of glucose or onto agar medium supplemented with the same nutrients used to fertilize our mycorrhization experiments.