I joined the Institute for Genomic Diversity in November of 2003 as a Post-Doc associate working with Stephen Kresovich on a NSF funded project (NSF grant DBI-0321467,Molecular and Functional Diversity of the Maize Genome).

At the IGD, I am working on Maize Diversity-Based Genomics. Specifically I'm working on the dissection of the inflorescence architecture in maize (maize tassel and ear) and the rapidly evolving ZmCLE gene family. In the near future we are also looking forward to work on the maize kernel mineral components.
The dissection of complex traits in maize is done by utilizing both association and linkage based approaches. To conduct these analyses, we are developing linkage and association populations that capture much of the natural variation inherent in the maize genome. Extensive phenotypic data and surveys of candidate gene sequences is employed. This approach should allow the rapid dissection of complex traits down to the gene level.

Rapidly evolving genes:
ZmCLE genes and the evolution of inflorescence architecture in maize
 
It is a difficult challenge to study the molecular basis of the long-term selection response because of the duration of the experiments that are required. When man tries to transform plants, generation after generation, so that they adapt to the cultivation techniques and ideotypes that he imposes, he achieves over long period of time such an experiment. Inflorescence architecture went through strong diversifying selection during maize domestication. We are developing a platform to rapidly dissect complex traits, such as inflorescence architecture, in maize by utilizing both association and linkage based approaches. Genes of the CLE family are essential to restrict the expression domain of regulatory genes that allow the maintenance of stem cells in the meristem. Such pathways are thought to be responsible for differences in organ shape. Unlike the sequences from the other genes involved in these pathways, CLE sequences are poorly conserved across species. We think that these genes could play a major role in plant phenotypic adaptation. CLE genes are being sequenced across a set of 300 maize lines and 16 lines of its wild relative teosinte. These lines capture most of the species' allelic diversity. Sequencing will also be done in closely related species. These genes will be tested for selection across the related species and subspecies. In addition, SNP and indel variation in these genes will be tested for phenotypic association in Maize.

In a few words, we will try for that gene family to answer the two following questions:

How has selection shaped molecular diversity?

How does the molecular diversity relate to functional trait variation?

In addition to the ZmCLE gene family we will be looking at other inflorescence architecture candidates genes.

Identifying genes involved in the phenotypic variation for inflorescence architecture in maize.

Candidate genes are chosen based on homology to genes of known function from other plants (rice or Arabidopsis) and from genes identified by the "Inflorescence Architecture in Maize" project (Sarah Hake). We also carry on a more extensive study of the ZmCLE gene family (many of them being potentially involved in the inflorescence architecture). These genes will be sequenced across a set of 300 diverse maize inbreds and tested for association(s) between their SNPs and indels and the phenotypic variation (that of our favorite trait).

Who am I (as I just joined the IGD, this is what I did in the years before)

Academic degrees:

PhD research. Conducted from December 1999 to present as a PhD from the School of Agronomy of Montpellier (ENSAM) In collaboration with the french Research Institute for Development (IRD). Advisor: Dr. Julien Berthaud

(French National Service. February 1998 to June 1999)

DEA (MSc). Obtained in September 1997 in quantitative genetics, plant breeding theory and population genetics. Dissertation advisor: Dr. Alain Ghesquiére

Maîtrise (Bachelor) in population Biology. Obtained in June 1996

Research work (see detailed resume of research work):

PhD Dissertation: The impact of farmer management practices on maize landrace genetic diversity in the Central Valleys of Oaxaca, Mexico

DEA (MSc) Dissertation: Characterization of rice polygenic resistance to the rice yellow mottle virus.

Fellowships and Scholarships:

Research Fellowship from the International Maize and Wheat improvement Center (CIMMYT). November 2002 to February 2003

Research Fellowship from the french Secretary of Science and Education. November 1999 to October 2002

Research Fellowship from the french Research Institute for Development (IRD). November 1999 to October 2002

Received a full Scholarship from the french Secretary of Science and Education as an undergraduate student from 1993 to 1997 when I graduated from the DEA (MSc)

Publications:

Pressoir G. And J. Berthaud. Effect of kernel color in structuring genetic diversity in maize landraces. (in preparation)

Pressoir G. And J. Berthaud. Population structure and strong divergent selection shape phenotypic diversification in maize landraces. Heredity (2004) 92, 95-101

Pressoir G. And J. Berthaud. Patterns of population structure in maize landraces from the Central Valleys of Oaxaca in Mexico. Heredity(2004) 92,

Ahmadi N., Albar L, Pressoir G., Pinel A., Fargette D. and A. Ghesquiére. Genetic basis and mapping of the resistance to Rice yellow mottle virus. III. Analysis of QTL efficiency in introgressed progenies confirmed the hypothesis of complementary epistasis between two resistance QTLs. Theor Appl Genet (2001) 103:1084-1092.

Pressoir G., Albar L., Ahmadi N., Rimbault I., Lorieux M., Fargette D. and A. Ghesquiére. Genetic basis and mapping of the resistance to rice yellow mottle virus. II. Evidence of a complementary epistasis between two QTLs. Theor Appl Genet(1998) 97:1155-1161.

Presentations and posters:

Pressoir G, Krill A, Vroh Bi I, Brown P, Buckler E and Kresovich E, 2004. Identifying the allelic variation associated with the maize inflorescence architecture. The Quest for ZmCLV3. Poster at the Maize Genetics Conference, Mexico City, Mexico.

Pressoir G and Berthaud J. 2003. Impact de la gestion paysanne sur la differenciation phenotypique des populations de ma•s dans les Vallees Centrales de Oaxaca au Mexique. Presentation given at the XXV^i�me Reunion Annuelle du Groupe de Biologie et Genetique des Populations. Toulouse, France

Pressoir G and Berthaud J, 2003. The impact of farmer management practices on maize landrace genetic diversity. Poster at the Maize Genetics Conference, Lake Geneva, WI.

Pressoir G and Berthaud J, 2002. Population structure and strong divergent selection shape phenotypic evolution in maize landraces. Poster at the Maize Genetic Conference, Orlando, FL.

Pressoir G and Berthaud J, 2001. Diversifying selection among maize landraces: Farmer management of maize gentic diversity. Presentation given at Evolution 2001, Knoxville, TN.

Albar L, Pressoir G, Ahmadi N, Fargette D, Lorieux M and A Ghesquiére, 1998. Mapping of quantitative trait loci controlling resistance to rice yellow mottle virus in an indica « japonica double haploid population. Poster at the Plant & Animal Genome VI conference, San Diego, CA.