Barbara Ambrose

Assistant Curator of Plant Genomics, The New York Botanical Garden

Ph.D., UCSD
San Diego, CA (2000)
Floral Organ Specification in Zea mays.
Expertise: Plant genomics, morphology, evolution and development

Profile

My main research interest is in understanding the molecular genetic basis of plant morphological diversity. My work includes investigations of the development of morphology using scanning electron microscopy and histological sections as well investigations of gene function in development. I started my research career working with angiosperms particularly the monocots, Zea mays and Lacandonia schismatica, and used a variety of approaches to understand distinct morphological features within these two species. Research in both species involved the investigation of the role of MADS-box genes in the development of these plants. These evolutionary developmental (evo-devo) studies have provided molecular genetic evidence to support the homology between the grass specific lodicule in Zea mays and petals and to understand the inverted reproductive structures in Lacandonia schismatica. Although I have a few projects investigating floral MADS-box genes in diverse species, the vast majority of my research has recently moved away from the angiosperms to understanding the morphology of lycophytes and ferns. My evolutionary developmental research at NYBG is synergistic and enhanced by the expertise of garden scientists in the morphology of lycophytes and ferns.

Evolution and development in lycophytes and ferns

Lycophytes occupy a key phylogenetic position within the land plants as sister to all other vascular plants. The morphology of lycophytes has shown little change for more than 350 million years. There are key morphological features found in lycophytes such as microphylls, heterospory, endosporic gametophyte development, as well as the origin of vasculature and a sporophyte dominant life cycle. In addition, the lycophytes have several enigmatic features including the rhizophore and ligule. Given these features, it is necessary to elucidate the molecular genetic networks underlying the development of these key structures in lycophytes because they are integral to understanding the evolution and development of all vascular plants, the dominant component of the land flora and economic botany. In collaboration with Dr. Dennis Stevenson, we are working on generating a functional model organism in lycophytes. We have chosen Selaginella apoda due to its short life cycle and well studied biology. In addition, its genome has recently been sequenced.

The evolution and development of leaves has intrigued botanists for more than two centuries. Recent advances in developmental genetics in angiosperms have provided new tools to investigate hypotheses of leaf homology and evolution. Comparatively little is known about the developmental genetics of fern or lycophyte leaf development yet ferns and lycophytes occupy key phylogenetic positions in the land plants and data in these groups are important for understanding larger questions of leaf homology and evolution. In collaboration with garden scientists, Drs. Robbin Moran and Alejandra Vasco, we are investigating the development of leaves in Elaphoglossum section Squamipedia. Dr. Moran’s taxonomic and phylogenetic studies have shown that at least three of the species in Elaphoglossum section Squamipedia appear to have reverted from a simple leaf to a dissected leaf morphology. We are investigating the molecular genetic basis of Elaphoglossum fern leaf diversity and evolution by cloning and analyzing the expression of candidate genes (namely KNOX and Class III HD-Zip genes) and studying leaf development in our study species. This research is supported by the National Science Foundation and combines an investigation into the taxonomy and phylogeny of Elaphoglossum section Squamipedia with an evo-devo study of its leaves. In addition, we are cloning and investigating the expression and phylogeny of leaf development genes in lycophytes and ferns. These data should help us to better understand the evolution and development of microphylls and megaphylls in the land plants.

MADS-box genes in land plant evolution

MADS-box genes are most well known for their role in floral organ specification. We are studying the role of MADS-box genes in plants that do not form flowers, namely mosses and lycophytes. The entire complement of MADS-box genes is known from the sequenced genomes of Physcomitrella patens, Selaginella moellendorffii and S. apoda. Our molecular genetic studies will help to understand the role MADS-box genes played in the evolution and development of land plants.

Acknowledgements

My research is funded by Lewis B. and Dorothy Cullman and the National Science Foundation.

Selected publications

E.R. Álvarez-Buylla*, B.A. Ambrose*, E. Flores-Sandoval*, F. Vergara-Silva*, M. Englund, A. Garay-Arroyo, B. García-Ponce, E. de la Torre-Bárcena, S. Espinosa-Matías, E. Martínez, A. Piñeyro-Nelson, P. Engström and E.M. Meyerowitz (2010) B-function expression in the flower center underlies the homeotic phenotype of Lacandonia schismatica (Triuridaceae). Plant Cell 22: 3543-3559. *These authors contributed equally.

K. Prasad, X. Zhang, E. Tobón and B.A. Ambrose. (2010) The Arabidopsis B-sister MADS-box protein, GORDITA, represses fruit growth and contributes to integument development. The Plant Journal 62: 203-214.

Ambrose, B.A. (2010) MADS-Box Genes in Plant Evolution and Development. International Journal of Plant Developmental Biology 4: 30-37.

B.A. Ambrose, S. Espinosa-Matías, S. Vázquez-Santana, F. Vergara-Silva, E. Martínez, J. Márquez-Guzmán and E. Alvarez-Buylla. (2006) Comparative developmental series of the Mexican triurids support an euanthial interpretation for the unusual reproductive axes of Lacandonia schismatica (Triuridaceae). Am. J. Bot. 93: 15-35.

Websites

http://sweetgum.nybg.org/elaphoglossum/index.php