Arabidopsis VERNALIZATION2 （VRN2）, EMBRYONIC FLOWER2 （EMF2）, and FERTILIZATION-INDEPENDENT SEED2 （FIS2） are involved in vernalization-mediated flowering, vegetative development, and seed development, respectivel...Arabidopsis VERNALIZATION2 （VRN2）, EMBRYONIC FLOWER2 （EMF2）, and FERTILIZATION-INDEPENDENT SEED2 （FIS2） are involved in vernalization-mediated flowering, vegetative development, and seed development, respectively. Together with Arabidopsis VEF-L36, they share a VEF domain that is conserved in plants and animals. To investigate the evolution of VEF-domain-containing genes （VEF genes）, we analyzed sequences related to VEF genes across land plants. To date, 24 full-length sequences from 11 angiosperm families and 54 partial sequences from another nine families were identified. The majority of the full-length sequences identified share greatest sequence similarity with and possess the same major domain structure as Arabidopsis EMF2. EMF2-1ike sequences are not only widespread among angiosperms, but are also found in genomic sequences of gymnosperms, lycophyte, and moss. No FIS2- or VEF-L36-1ike sequences were recovered from plants other than Arabidopsis, including from rice and poplar for which whole genomes have been sequenced. Phylogenetic analysis of the full-length sequences showed a high degree of amino acid sequence conservation in EMF2 homologs of closely related taxa. VRN2 homologs are recovered as a clade nested within the larger EMF2 clade. FIS2 and VEF-L36 are recovered in the VRN2 clade. VRN2 clade may have evolved from an EMF2 duplication event that occurred in the rosids prior to the divergence of the eurosid I and eurosid II lineages. We propose that dynamic changes in genome evolution contribute to the generation of the family of VEF-domain-containing genes, Phylogenetic analysis of the VEF domain alone showed that VEF sequences continue to evolve following EM F2NRN2 divergence in accordance with species relationship. Existence of EMF2-1ike sequences in animals and across land plants suggests that a prototype form of EMF2 was present prior to the divergence of the plant and animal lineages. A proposed sequence of events, based on domain organization and occurrence of intermediate sequences throughout angiosperms, could explain VRN2 evolution from an EMF2-1ike ancestral sequence, possibly following duplication of the ancestral EMF2. Available data further suggest that VEF-L36 and FIS2 were derived from a VRN2-1ike ancestral sequence. Thus, the presence of VEF-L36 and FIS2 in a genome may ultimately be dependent upon the presence of a VRN2-1ike sequence.展开更多
基金ACKNOWLEDGMENTS The authors thank Dr Hong Ma （Pennsylvania State University）, the Floral Genome Project, the and the SOL Genomics Network （www.sgn.cornell.edu/） for providing EMF2 homologous eDNA clones, Kazusa DNA Research Institute for providing Lotus japonica EMF2 sequence to Dr Rieko Nishimura, Dr Jo Ann Banks （National Science Foundation/Purdue University） for providing Selaginella EMF2 homologous ESTsequences0 Dr Ralph Quatrano （Washington University） for providing access to the Physcomitrella website, Drs Hong Ma and Damon R. Lisch （UC Berkeley） for comments of the manuscript, Steve Ruzin and Denise Schichnes （Bioimaging Facility, CNR, UC Berkeley） for image processing, and our laboratory members Myriam Calonje, Tiffany Tirtadinata, Robert Luan, Heather Driscoll, and Rosario Sanchez for help and support in preparation of this work. No conflict of interest declared.
文摘Arabidopsis VERNALIZATION2 （VRN2）, EMBRYONIC FLOWER2 （EMF2）, and FERTILIZATION-INDEPENDENT SEED2 （FIS2） are involved in vernalization-mediated flowering, vegetative development, and seed development, respectively. Together with Arabidopsis VEF-L36, they share a VEF domain that is conserved in plants and animals. To investigate the evolution of VEF-domain-containing genes （VEF genes）, we analyzed sequences related to VEF genes across land plants. To date, 24 full-length sequences from 11 angiosperm families and 54 partial sequences from another nine families were identified. The majority of the full-length sequences identified share greatest sequence similarity with and possess the same major domain structure as Arabidopsis EMF2. EMF2-1ike sequences are not only widespread among angiosperms, but are also found in genomic sequences of gymnosperms, lycophyte, and moss. No FIS2- or VEF-L36-1ike sequences were recovered from plants other than Arabidopsis, including from rice and poplar for which whole genomes have been sequenced. Phylogenetic analysis of the full-length sequences showed a high degree of amino acid sequence conservation in EMF2 homologs of closely related taxa. VRN2 homologs are recovered as a clade nested within the larger EMF2 clade. FIS2 and VEF-L36 are recovered in the VRN2 clade. VRN2 clade may have evolved from an EMF2 duplication event that occurred in the rosids prior to the divergence of the eurosid I and eurosid II lineages. We propose that dynamic changes in genome evolution contribute to the generation of the family of VEF-domain-containing genes, Phylogenetic analysis of the VEF domain alone showed that VEF sequences continue to evolve following EM F2NRN2 divergence in accordance with species relationship. Existence of EMF2-1ike sequences in animals and across land plants suggests that a prototype form of EMF2 was present prior to the divergence of the plant and animal lineages. A proposed sequence of events, based on domain organization and occurrence of intermediate sequences throughout angiosperms, could explain VRN2 evolution from an EMF2-1ike ancestral sequence, possibly following duplication of the ancestral EMF2. Available data further suggest that VEF-L36 and FIS2 were derived from a VRN2-1ike ancestral sequence. Thus, the presence of VEF-L36 and FIS2 in a genome may ultimately be dependent upon the presence of a VRN2-1ike sequence.
