Ph.D. Genetics University of Missouri-Columbia, 1978
B.S. Biology Illinois State University, 1973
We study plant reproduction using biochemistry, cell biology, genetics and molecular biology, in 3 projects: 1) Pollen tube growth: we characterize signal transduction pathways mediated through pollen-specific receptor kinases; 2) Pollen development and function: we characterize mutations that affect transmission through the male parent; and 3) Gamete biology: we characterize sperm, egg, or embryo sac-expressed genes that may play roles in pollen tube guidance, gamete recognition or fusion.
Molecular Biology of Plant Reproduction
Pollen Tube Growth
We study pollen-specific receptor kinases and how they perceive and transduce signals for pollen tube growth. We used yeast two hybrid screens to identify potential ligands; these include LAT52 and LeSHY, pollen proteins, and LeSTIG1, a stigma-specific protein. We think that the receptor kinases interact with different ligands during different phases of pollen tube growth. We also used yeast two hybrid screens to identify cytoplasmic partners for these receptor kinases; one partner, called KPP, is a guanine nucleotide exchange factor for Rops. Rops are small GTPases. Thus our work provides a link from receptor kinases to the Rop-mediated cytoplasmic dynamics that are needed for pollen tube growth.
Pollen tubes (stained with decolorized aniline blue) growing through a tomato style.
Pollen development and function
About 10% of the genes in plants are specifically or selectively expressed in pollen, but the functions of most are not understood. We use Arabidopsis to identify mutants that are defective at a stage of pollen development, or during pollen hydration, pollen tube growth, pollen tube guidance, or fertilization. Usually such mutants have altered transmission through the male parent, but do not affect the female.
The giftwrap pollen mutant has what appears to be ribbons tied in bows inside the pollen grain (stained with decolorized aniline blue).
We are interested in double fertilization, specifically in how the two sperm and their fusion partners, the egg and the central cell, recognize and fuse with each other. To develop tools for this objective, we generated cDNA libraries from maize sperm, eggs, and embryo sacs, sequenced ~20,000 ESTs, then used these datasets as starting points to identify gamete-specific genes. We identified promoter elements that will drive gamete-specific gene expression. We then use Arabidopsis to identify T-DNA insertions in gamete-expressed genes, and test whether there is a phenotype. We have evidence that fertilization fails when some of these genes are disrupted.
For pdfs of these and other papers, see the McCormick web site.
McCormick, S. 2013. Pollen (Quick Guide). Current Biology 23: R988-R990.
Zhao, X-Y., Wang, Q., Li., S., Ge., F-R., Zhou, L-Z., McCormick, S. and Zhang, Y. 2013. The juxtamembrane and carboxy-terminal domains of Arabidopsis PRK2 are critical for ROP-induced growth in pollen tubes. J. Experimental Botany (in press, accepted August 30; doi: 10.1093/jxb/ert323).
Boavida, L.C., Qin, P., Broz, M., Becker, J.D. and McCormick, S. 2013. Arabidopsis tetraspanins are confined to discrete expression domains and cell types in reproductive tissues and form homo- and hetero-dimers when expressed in yeast. Plant Physiology 163: 696-712; doi: 10.1104/pp.113.216598.Li, S., Zhou, L-Z., Feng, Q-N., McCormick, S. and Zhang, Y. 2013. The C-terminal hypervariable domain targets Arabidopsis ROP9 to the invaginated pollen tube plasma membrane.
Ron, M., Alandete-Saez, M., Williams, L., Fletcher, J. and McCormick, S. 2010. Proper regulation of a sperm-specific cis-nat-siRNA is essential for double fertilization in Arabidopsis. Genes & Development 24:1010-1021, doi:10.1101/gad.1882810.
Muschietti, J. and McCormick, S. 2010. Abscisic acid (ABA) receptors: light at the end of the tunnel. F1000 Biology Reports 2:15 (http://f1000biology.com/reports/10.3410/B2-15/).
Zhang, Y.*, He, J.*, Lee, D. and McCormick, S. 2010. Interdependence of endomembrane trafficking and actin dynamics during polarized growth of Arabidopsis pollen tubes. Plant Physiology 152:2200-2210. doi:10.1104/pp.109.142349. * co-first authors.
Wengier, D.L., Mazzella, M.A., Salem, T.M., McCormick, S. and Muschietti, J.P. 2010. STIL, a peculiar molecule from styles, specifically dephosphorylates the pollen receptor kinase LePRK2 and stimulates pollen tube growth in vitro. BMC Plant Biology 10:33 (http://www.biomedcentral.com/1471-2229/10/33)
Zhang, Y. and McCormick, S. 2009. The regulation of vesicle trafficking by small GTPases and phospholipids during pollen tube growth. Sexual Plant Reprod. 23:87-93; doi:10.1007/s00497-009-0118-z.
Zhang, Y. and McCormick, S. 2009. AGC VIII kinases: at the crossroads of cellular signaling. Trends Plant Sci. 14: 689-695.
Boavida, L.C., Shuai, B., Yu, H-J., Pagnussat, G. C., Sundaresan, V. and McCormick, S. 2009. A collection of Ds insertions associated with defects in male gametophyte development and function in Arabidopsis thaliana. Genetics 181: 1369-1385; doi:10.1534/genetics.108.090852.
Zhang, Y., He, J. and McCormick,S. 2009. Two Arabidopsis AGC kinases are critical for the polarized growth of pollen tubes. Plant Journal 58: 474-484; 10.1111/j.1365-313X2009.03792.x.
Wang, H., Boavida, L.C., Ron, M. and McCormick, S. 2008. Truncation of a protein disulfide isomerase, PDIL2-1, delays embryo sac maturation and disrupts pollen tube guidance in Arabidopsis thaliana. Plant Cell 20: 3300-3311; 10.1105/tpc.108.062919.
Zhang, D., Wengier, D., Shuai, B., Gui, C.P., Muschietti, J., McCormick, S. and Tang,W.H. 2008. The pollen receptor kinase LePRK2 mediates growth-promoting signals and positively regulates pollen germination and tube growth. Plant Physiology 148: 1368-1379; 10.1104/pp.108.124420.
Blanvillain, R., Boavida, L.C., McCormick, S. and Ow, D.W. 2008. Exportin1 genes are essential for development and function of the gametophytes in Arabidopsis thaliana. Genetics 180: 1493-1500; 10.1534/genetics.108.094896.
Borges, F., Gomes, G., Gardner,R., Moreno, N., McCormick, S., Feijo, J.A. and Becker, J.D. 2008. Comparative transcriptomics of Arabidopsis thaliana sperm cells. Plant Physiology 148: 1168-1181; 10.1104/pp.108.125229.
Alandete-Saez, M., Ron, M. and McCormick, S. 2008. GEX3, expressed in the male gametophyte and in the egg cell of Arabidopsis thaliana, is essential for micropylar pollen tube guidance and plays a role during early embryogenesis. Molecular Plant 1: 586-598.
Zhang, Y and McCormick, S. 2007. A distinct mechanism regulating a pollen-specific guanine nucleotide exchange factor for the small GTPase Rop in Arabidopsis thaliana. Proc. Natl. Acad. Sci. USA 104: 18830-18835.
Boavida, L.C. and McCormick, S. 2007. Temperature as a determinant factor for increased and reproducible in vitro pollen germination in Arabidopsis thaliana. Plant Journal 52: 570-582.
McCormick, S. 2007. Reproductive dialog. Science 317: 606-607.
Yang, H., Kaur, N., Kiriakopolos, S. and McCormick, S. 2006. EST generation and analyses towards identifying female gametophyte-specific genes in Zea mays L. Planta 224: 1004-1014.
Holmes-Davis, R., Tanaka, C.K., Vensel, W., Hurkman, W. and McCormick, S. 2005. Proteome mapping of mature pollen of Arabidopsis thaliana. Proteomics 5: 4864-4884.
Engel, M.L., Holmes-Davis, R. and McCormick, S. 2005. Green sperm. Identification of male gamete promoters in Arabidopsis thaliana. Plant Physiology 138: 2124-2133.
McCormick, S. and Yang, H. 2005. Is there more than one way to attract a pollen tube? Trends Plant Sciences 10: 260-263.
Kaothien, P., Ok, S.H., Shuai, B., Wengier, D., Cotter, R., Kelley, D., Kiriakopolos, S., Muschietti, J. and McCormick, S. 2005. Kinase partner protein interacts with the LePRK1 and LePRK2 receptor kinases and plays a role in polarized pollen tube growth. Plant Journal 42: 492-503.
Wang, Y., Magnard, J-L., McCormick, S. and Yang, M. 2004. Progression through meiosis I and meiosis II in Arabidopsis thaliana anthers is regulated by an A-type cyclin predominately expressed in prophase I. Plant Physiology 136: 4127-4135.
Johnson-Brousseau, S.A. and McCormick, S. 2004. A compendium of methods useful for characterizing Arabidopsis pollen mutants and gametophytically-expressed genes. Plant Journal 39: 761-775.
Guyon, V., Tang, W., Monti., M., Raiola, A., DeLorenzo, G., McCormick, S. and Taylor, L. 2004. Antisense phenotypes reveal a role for SHY, a pollen-specific leucine-rich repeat protein, in pollen tube growth. Plant Journal 39: 643-654.
Tang, W., Kelley, D., Ezcurra, I., Cotter, R. and McCormick, S. 2004. LeSTIG1, an extracellular binding partner for the pollen receptor kinases LePRK1 and LePRK2, promotes pollen tube growth in vitro. Plant Journal 39: 343-353.
McCormick, S. 2004. Control of male gametophyte development. Plant Cell 16: S142-153.
Wengier, D., Valsecchi, I., Cabanas, M.L., Tang, W., McCormick, S. and Muschietti, J. 2003. The receptor kinases LePRK1 and LePRK2 associate in pollen and when expressed in yeast, but dissociate in the presence of style extract. Proc. Natl. Acad. Sci. USA 100:6860-6865.
Engel, M.L., Chaboud, A., Dumas, C. and McCormick, S. 2003. Sperm cells of Zea mays have a complex complement of mRNAs. Plant Journal 34:697-707.
Tang, W., Ezcurra, I., Muschietti, J. and McCormick, S. 2002. A cysteine-rich extracellular protein, LAT52, interacts with the extracellular domain of the pollen receptor kinase LePRK2. Plant Cell 14: 2277-2287.
Yang, M. and McCormick, S. 2002. The Arabidopsis thaliana MEI1 gene likely encodes a protein with BRCT domains. Sexual Plant Reproduction 14:355-357.
Kim, H-Y., Cotter, R., Johnson, S., Senda, M., Dodds, P., Kulikauskas, R., Tang, W., Ezcurra, I., Herzmark, P. and McCormick, S. 2002. New pollen-specific receptor kinases identified in tomato, maize and Arabidopsis: the tomato kinases show overlapping but distinct localization patterns on pollen tubes. Plant Molecular Biology 50:1-16.
Cock, J.M. and McCormick, S. 2001. A large family of genes that share homology with CLAVATA3. Plant Physiology 126: 939-943.
Magnard, J-L., Yang, M., Chen, Y-C. S., Leary, M. and McCormick, S. 2001 The Arabidopsis thaliana gene Tardy Asynchronous Meiosis (TAM) is required for the normal pace and synchrony of cell division during male meiosis. Plant Physiology 127:1157-1166.
Johnson, S. and McCormick, S. 2001. Pollen germinates precociously in the anthers of raring-to-go, an Arabidopsis thaliana gametophytic mutant. Plant Physiology 126: 685-695.
Honors and Awards
Fellow - AAAS - 2011
Fellow - American Society of Plant Biologists - 2011
Luso-American Award for Sabbatical, Lisbon, Portugal, 2003
Judith Pool Award for Mentoring - Northern California Chapter, Assoc.Women in Science - 2002
Fulbright Award for Sabbatical, Lyon, France, 1997