Minisymposium 17: Evolution of Plant Development

Abs # 31004: Comparative analyses of Poppy MADS-box genes expressed during flower development

Presenter:	Zahn, Laura M, lmz2@psu.edu
Authors	Zahn, Laura M (A)   Hu, Yi  (A)   Arrington, Jenny M (A)   Landherr, Lena  (A)   Chiorean, Stephanie A (A)   Leebens-Mack, Jim  (A)   dePamphilis, Claude W (A)   Becker, A  (B)   Theissen, G.  (B)   Ma, Hong  (A)
Affiliations:	(A): The Pennsylvania State University (B): University of Jena

Molecular genetic studies in Arabidopsis and other model plants have uncovered a large number of genes that play critical roles in controlling flower development. These include the ABC genes and other members of the MADS-box gene family. Although homologs of many MADS-box genes have been isolated and analyzed from many eudicots and some monocots, it is not clear how conserved these genes are among divergent angiosperm lineages, particularly in basal eudicots and basal angiosperms. The Floral Genome Project was initiated to identify and examine components of the genetic architecture of floral development using comparative genomic approaches. One of the goals of the FGP is to identify and study the evolutionary history of genes homologous to genes of known function in Arabidopsis and other model plant species. Several thousand cDNAs are to be sequenced from libraries constructed with mRNA from young floral buds or young reproductive shoots. Fifteen species, thirteen angiosperms and 2 gymnosperms will be studied, including the basal eudicot Eschscholzia californica (California poppy). A cDNA library was constructed from pre-meiotic floral buds and random EST sequencing has identified five MADS-box genes. These MADS-box genes share homology with several Arabidopsis genes with known floral functions. The phylogenetic placements of these genes are being investigated and in situ RNA hybridizations are being performed with young floral buds to determine the expression patterns of these genes. Similar expression patterns in poppy to their Arabidopsis homologs would support functional conservation, whereas differences in expression may point to possible divergence. Preliminary in situ hybridization results reveal that these five genes have different expression patterns that support the hypothesis that they are functional homologs of known A, B, C, and/or E genes. The expression of these genes in developing floral whorls suggests that they are involved in regulating the development of floral organs. The expression patterns of two of these genes are similar to known Arabidopsis and Antirrhinum genes. Because of the basal position of Eschscholzia in eudicot history, this suggests that some floral homologs may have retained common gene functions throughout the major eudicot lineages. This work was supported by the US National Science Foundation Plant Genome Program.