title: FW2.2 and cell cycle control in developing tomato fruit: a possible example of gene co-option in the evolution of a novel organ.
abstract: fw2.2 is one of the few QTLs thus far isolated from plants and the first one known to control fruit size. While it has been established that FW2.2 is a regulator (either directly or indirectly) of cell division, FW2.2 does not share sequence homology to any protein of known function (Frary et al. Science 289:85-88, 2000; Cong et al. Proc Natl Acad Sci USA 99:13606-13611, 2002; Liu et al. Plant Physiol 132:292-299, 2003). Thus, the mechanism by which FW2.2 mediates cell division in developing fruit is currently unknown. In an effort to remedy this situation, a combination of yeast two-hybrid screens, in vitro binding assays and cell bombardment studies were performed. The results provide strong evidence that FW2.2 physically interacts at or near the plasma membrane with the regulatory (beta) subunit of a CKII kinase. CKII kinases are well-studied in both yeast and animals where they form part of cell cycle related signaling pathway. Thus while FW2.2 is a plant-specific protein and regulates cell division in a specialized plant organ (fruit), it appears to participate in a cell-cycle control signal transduction pathway that predates the divergence of single- and multi-cellular organisms. These results thus provide a glimpse into how ancient and conserved regulatory processes can be co-opted in the evolution of novel organs such as fruit.
authors.affiliation: Department of Plant Breeding and Genetics, Cornell University, Emerson Hall 240, Ithaca, NY, 14853, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Cong
authors.forename: Steven D
authors.initials: SD
authors.lastname: Tanksley
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D019470:Biolistics / Q000379:methods; D047390:Casein Kinase II / Q000235:genetics / Q000378:metabolism; D002453:Cell Cycle / Q000235:genetics*; D002462:Cell Membrane / Q000378:metabolism; D002874:Chromosome Mapping; D018076:DNA, Complementary / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D005638:Fruit / Q000235:genetics* / Q000254:growth & development; D018628:Gene Dosage; D018506:Gene Expression Regulation, Plant; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D018551:Solanum lycopersicum / Q000235:genetics* / Q000254:growth & development; D018613:Microscopy, Confocal; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D019697:Onions / Q000166:cytology / Q000378:metabolism; D010802:Phylogeny; D011485:Protein Binding; D040641:Quantitative Trait Loci / Q000235:genetics*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D020798:Two-Hybrid System Techniques
chemical_list: D018076:DNA, Complementary; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D047390:Casein Kinase II