title: Genome-wide analysis of the MADS-box gene family in Populus trichocarpa.
abstract: Populus trichocarpa (poplar) is distinguished from its herbaceous counterparts Arabidopsis and rice by its woody structure, perennial life cycle, and dioecious, two-whorled flowers. MADS-box genes are known to be involved in many important processes during plant development. Investigation of the poplar genome revealed 105 putative functional MADS-box genes and 12 pseudogenes. These numbers are comparable to those in Arabidopsis. However, poplar has 64 type II MADS-box genes, implying a higher birth rate when compared with Arabidopsis (64 vs.47). In addition to duplications for floral organ identity genes, TM3-like, StMADS11, ANR1 and Bs clades were significantly increased. As indicated by the phylogenetic analysis, there exist at least two MIKC* MADS-box genes in the poplar genome. In contrast, only 41 putative functional type I genes and 9 pseudogenes were found, suggesting that the poplar type I MADS-box genes have experienced a lower rate in both birth and death. Poplar MADS-box genes were distributed on all linkage groups (LGs), except LG XIX. Like other gene families, poplar MADS-box gene family has expanded through tandem gene duplication and segmental duplication events as demonstrated by two genomic regions where clustered MADS-box genes exhibited high similarities in the MADS-box domains. A survey of poplar EST sequences showed that MADS-box genes were expressed in wood and cambium tissues, which are specific to woody plants. The expression of common MADS-box gene in tree-specific tissues suggests that the novel function combinations of a set of genes similar to those in herbaceous plants may account for the development of woody characteristics in poplar.
authors.affiliation: Department of Biological Sciences, Northern Illinois University, DeKalb, IL 60115, USA.
authors.forename: Charles H
authors.initials: CH
authors.lastname: Leseberg
authors.forename: Aili
authors.initials: A
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Kang
authors.forename: Melvin
authors.initials: M
authors.lastname: Duvall
authors.forename: Long
authors.initials: L
authors.lastname: Mao
mesh_terms: D017360:Arabidopsis / Q000235:genetics; D019143:Evolution, Molecular; D020440:Gene Duplication; D017343:Genes, Plant; D018745:Genome, Plant; D026161:MADS Domain Proteins / Q000235:genetics; D008957:Models, Genetic; D005810:Multigene Family; D012275:Oryza / Q000235:genetics; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics; D032107:Populus / Q000235:genetics* / Q000254:growth & development; D011544:Pseudogenes; D013045:Species Specificity
chemical_list: D026161:MADS Domain Proteins; D010940:Plant Proteins