| Carrot (Daucus carota L.) ranks among the top ten most popular vegetable crops in the world. It isa biennial plant with an obligatory vernalization requirement. Spring cultivation makes them vulnerableto vernalization and hence bolting, which involves interaction between low temperature and light.Premature bolting has become the bottleneck in winter and early spring carrot production. It is useful tounderstand the mechanism of premature bolting regulation for breeding anti-bolting carrot varieties. SongZi‘wild carrot (P1) and Amsteram‘carrot (P4) was used to understand environmental regulationof carrot bolting. It was demonstrated that vernalization is indispensable for carrot initiating to flower,and that long day condition after vernalization had a promotive effect on bolting. RNA-seq wasperformed during bolting induction using P1and P4. de novo assembly of transcriptome sequencegenerated76997unigenes with a mean length of666bp. Of these,47796were annotated againstpublic protein databases.47gene homologues were putatively correspond to genes of all known geneticflowering pathways, such as GI, COL and FRI, FLC, the key regulation genes in photoperiod pathwayand vernalization pathway, respectively. Flowering signals intergrator SOC1also been detected in ourstudy. There were three FLC homologs in carrot (DcFLC1, DcFLC2and DcFLC3), of these, DcFLC3only expressed in late-flowering cultivar P4. The results of RT-PCR in seven carrot germplasmsconfirmed that DcFLC3may be in connection with sensitivity to temperature. Phylogeneticrelationships among FLC genes showed that DcFLCs clustered with perennial plants, and DcFLC2hasan earlier differentiation during envolution. qPCR experiments revealed that DcFLC1and DcFLC3were mainly induced by vernalization, while light influnced DcFLC2expression most, especially in P1.The distinctive expression profiles of DcFLCs in response to cold and light suggested a different role inflowering pathway. |
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