Poster: Evolution

Abs # 783: Moss MADS-box and KNOX Genes Knocked Out

Presenter:	Singer, Stacy D., stacysinger@hotmail.com
Authors	Singer, Stacy D. (A)   Ashton, Neil W. (A)
Affiliations:	(A): University of Regina

MADS-box genes are involved in many ontogenetic processes including differentiation of floral meristems and determination of floral organ identities. KNOX genes, a group of plant homeobox genes, are essential for the generation and/or maintenance of shoot apical meristems. Since flowers are the hallmark of angiosperms and all above-ground parts of a flowering plant are derived from the shoot apical meristem, phylogenetic and functional analyses of members of these gene families from non-flowering plants should impart a more profound understanding of the origin and evolution of the various major land plant groups and the structures that characterize each of them. Physcomitrella patens is an attractive system for studying the functions of MADS-box and KNOX gene homologues, as in addition to its phylogenetically basal position, simple life cycle and similarities to higher plants, it is especially amenable to gene targeting. We have generated single and double knock-out strains involving the three known P. patens KNOX genes (MKN1-3, MKN2 and MKN4), and confirmed their knocked out status at the molecular level. We have also confirmed the knocked out status of strains in each of which one of two MADS-box genes (PPM1 and PPM2) has been targeted. The phenotypes of all MKN and most PPM knock-out strains are normal, probably because of functional redundancy within each gene family. However, in a few PPM knock-out strains, the production of sporophytes is delayed. This agrees with the observation that PPM1 antisense strains also exhibit delayed sporophyte production, indicating that PPM1 may function in moss reproductive development. Experiments to generate triple MKN and double PPM knock-out strains are in progress as are expression studies of the individual genes.