Isolation and functional characterization of SVP-like genes in Prunus mume

- We describe isolation and functionally analysis of PmSVP1 and PmSVP2 in Prunus mume.
- PmSVP1 and PmSVP2 were generally expressed in vegetative tissues in Prunus mume.
- Expression analysis during flower bud differentiation suggested their involvement in floral initiation.
- Overexpression of PmSVP1 in Arabidopsis delayed flowering and led to abnormal flower organ.

The MADS-box gene SVP (SHORT VEGETATIVE PHASE) mediates the integration of signals involved in the control of flowering time and flower development by interacting with MADS-box proteins. Although SVP-like genes have been isolated from a wide range of plant species, their orthologs are not well-characterized in Prunus mume (mei), an important ornamental and fruit plant in the East Asia. To determine the role of SVP-like genes in mei flowering, two MADS-box genes with homology to Arabidopsis SVP, PmSVP1 and PmSVP2, have been identified and analyzed in mei and functionally characterized in Arabidopsis. Phylogenetic analyses revealed that PmSVP1 and PmSVP2 fall into different sub-groups within the SVP-like gene group, which suggests distinct functions. Furthermore, expression was generally found in vegetative tissues, and decreased during flower bud differentiation development suggesting a role for these genes in the transition from the vegetative to reproductive phase. Overexpression of PmSVP1 and PmSVP2 in Arabidopsis led to a range of floral phenotype changes including additional trichomes, leaf-like sepals and increased rosette branches, whereas only PmSVP1 expression delayed flowering through down-regulation of FLOWERINGLOCUST (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). These results suggested that SVP-like genes in mei might have distinct roles during development of flowering. Our findings will help elucidate the molecular mechanisms important for the transition from vegetative to reproductive development in mei.