Abstract
BackgroundChrysanthemum is a leading cut flower species. Most conventional cultivars flower during the fall, but the Chrysanthemum morifolium ‘Yuuka’ flowers during the summer, thereby filling a gap in the market. To date, investigations of flowering time determination have largely focused on fall-flowering types. Little is known about molecular basis of flowering time in the summer-flowering chrysanthemum. Here, the genome-wide transcriptome of ‘Yuuka’ was acquired using RNA-Seq technology, with a view to shedding light on the molecular basis of the shift to reproductive growth as induced by variation in the photoperiod.ResultsTwo sequencing libraries were prepared from the apical meristem and leaves of plants exposed to short days, three from plants exposed to long days and one from plants sampled before any photoperiod treatment was imposed. From the ~316 million clean reads obtained, 115,300 Unigenes were assembled. In total 70,860 annotated sequences were identified by reference to various databases. A number of transcription factors and genes involved in flowering pathways were found to be differentially transcribed. Under short days, genes acting in the photoperiod and gibberellin pathways might accelerate flowering, while under long days, the trehalose-6-phosphate and sugar signaling pathways might be promoted, while the phytochrome B pathway might block flowering. The differential transcription of eight of the differentially transcribed genes was successfully validated using quantitative real time PCR.ConclusionsA transcriptome analysis of the summer-flowering cultivar ‘Yuuka’ has been described, along with a global analysis of floral transition under various daylengths. The large number of differentially transcribed genes identified confirmed the complexity of the regulatory machinery underlying floral transition.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-3024-4) contains supplementary material, which is available to authorized users.
Highlights
Chrysanthemum is a leading cut flower species
The outputs of the various pathways are integrated by the products of the floral integrator genes FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS (SOC1), which promote flowering by inducing the expression of the floral meristem identity genes LEAFY (LFY) and APETALA1(AP1) [4,5,6]
Transcriptome sequencing and read assembly To generate a broad survey of genes involved in floral transition induced by different photoperiod, six mRNA libraries were constructed respectively from six different samples of leaves and shoots apical meristem, and denoted CK, S1, S2, L1, L2 and L3 (Fig. 1)
Summary
Chrysanthemum is a leading cut flower species. Most conventional cultivars flower during the fall, but the Chrysanthemum morifolium ‘Yuuka’ flowers during the summer, thereby filling a gap in the market. Little is known about molecular basis of flowering time in the summer-flowering chrysanthemum. In the model plant Arabidopsis thaliana, floral transition is controlled by an intricate regulatory network comprising six distinct pathways, namely the photoperiod, the autonomous, the vernalization, the gibberellin (GA), the ambient temperature and the age pathways [2, 4]. The autonomous and vernalization pathways activate flowering by down-regulating the floral repressor gene FLC, which encodes a MADS-box transcription factor acting to repress the floral integrators [1, 10]. SQUAMOSA PROMOTER BINDING LIKE (SPL) transcription factors promote flowering by inducing the expression of the floral integrators LFY, FRUITFULL (FUL) and SOC1 [4]. In addition to photoperiod and ambient temperature, flowering time can be affected by the content of trehalose-6-phosphate (T6P), acting through the sugar signaling pathway [13, 14]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
