Narcissus tazetta SVP-like gene NSVP1 affects flower development in Arabidopsis

SHORT VEGETATIVE PHASE (SVP) related genes have important functions in regulating floral transition and inflorescence structure in many plant species. Some SVP related genes have been shown associated with dormancy transition. Narcissus tazetta var. chinensis exhibits summer dormancy release and floral transition promoted by extended high temperature exposure. However, the molecular mechanism underlying such development remains unknown. In this study, we isolated and characterized one SVP-like gene, NSVP1 from N. tazetta var. chinensis. The results of RT-PCR and in situ hybridization assay showed that NSVP1 was expressed in both vegetative and floral tissues. The highest level of NSVP1 in the bulb apices was detected when the above-ground just senesced and its transcripts declined gradually during endo-dormany. The lowest level was found at the beginning of flower differentiation and the release of endo-dormancy. These data suggest that NSVP1 is differentially regulated coordinately with endo-dormancy induction and release. Ectopic expression of NSVP1 neither complemented the early flowering phenotype of svp mutant nor altered the rosette leaf number in Col background. However, NSVP1 in svp mutant and Ler plants increased the number of lateral inflorescence and caused abnormal floral morphologies. In addition, strong expression of NSVP1 in Ler background affected plastochron. These results suggest that NSVP1 might play a role in the regulation of flower development.