Professor of Biology
B.S. University of Wisconsin, Madison
Ph.D. University of California, Los Angeles
Gary Drews' Lab Page
Gary Drews' PubMed Literature Search
Molecular Biology Program
Our lab studies the control of seed development. Our current focus is on development of the endosperm, which surrounds the embryo within the seed. Endosperm is an important component of the seed because it provides nutrients and developmental signals to the embryo during seed development. Furthermore, endosperm is an important source of food, as approximately two-thirds of human calories are derived from endosperm. In addition, endosperm is used as a raw material for numerous industrial products including ethanol.
Our goal is to understand the gene regulatory networks (GRNs) controlling endosperm development in maize. Maize endosperm initially develops as a coenocyte (mitosis without cellularization) and then becomes cellularized when the coenocyte consists of ~128 nuclei. Soon after cellularization, the endosperm differentiates into four different cell types: the starchy endosperm (SE), which synthesizes and accumulates starch and storage proteins; the basal transfer layer (BETL), which transports nutrient solutes from the maternal vascular tissue to the SE; the aleurone (AL), a single peripheral layer of cells that functions in germination; and the embryo surrounding region (ESR), which has unknown function but may be involved in signaling to and/or pathogenic defense of the developing embryo.
One of our main goals is to understand the GRNs operating in each of the endosperm cell types that activate specific gene sets necessary for cell differentiation and establishment of the unique functions of each cell type. This project is carried out in collaboration with the Yadegari lab at the University of Arizona (http://cals.arizona.edu/spls/content/ramin). We first identified the genes expressed in the individual cell types using laser capture microdissection (LCM) in combination with RNA-Seq. Analysis of the LCM dataset identified gene sets expressed predominantly in each of the cell types. For each these cell-specific gene sets, we are determining which transcription factors regulate which genes.
We currently are analyzing the BETL gene set, which contains ~600 genes. MEME analysis identified 10 short (~12 bp) sequence motifs overrepresented in the promoters of the genes in this gene set. We are using directed yeast one-hybrid assays (Y1H) assays to determine which transcription factors bind to which genes in the BETL gene set. For example, one of the transcription factors present in the BETL gene set is MYBR1 and Y1H assays showed that MYBR1 binds to three of these motifs. These three motifs are present in the promoters of ~75 genes within the BETL gene set, suggesting that these genes are direct targets of MYBR1. Consistent with this, we have shown, using Y1H assays, that MYBR1 binds to the promoters of 35 of these genes. Over the next few years, we will be identifying the targets of the other transcription factors in the BETL gene set, as well as in the other cell-specific gene sets.
Fluorescence microscopy of transgenic plants containing promoter: GFP constructs expressed specifically in the egg cell (upper left), synergid cells (lower left), antipodal cells (upper middle), central cell (lower middle), developing embryo (upper right), and developing endosperm (lower right).
- Zhan, J., Thakare, D., Ma, C., Lloyd, A., Nixon, N.M., Arakaki, A.M., Burnett, W.J., Logan, K.O., Wang, D., Wang, X., Drews, G.N., Yadegari, R. (2015) RNA sequencing of laser-capture microdissected compartments of the maize kernel identifies regulatory modules associated with endosperm cell differentiation. Plant Cell 27, 513-31.
- Li, G., Wang, D., Yang, R., Logan, K., Chen, H., Zhang, S., Skaggs, M.I., Lloyd A., Burnett, W.J., Laurie, J.D., Hunter, B.G., Dannenhoffer, J.M., Larkins, B.A., Drews, G.N., Wang, X., Yadegari, R. (2014) Temporal patterns of gene expression in developing maize endosperm identified through transcriptome sequencing. Proc. Natl. Acad. Sci. 111, 7582-7587.
- Rabiger, D.S., Drews, G.N. (2013) MYB64 and MYB119 are required for cellularization and differentiation during female gametogenesis in Arabidopsisthaliana. PLoS Genetics 9, e1003783.
- Belmonte, M.F., Kirkbride, R.C., Stone, S.L., Pelletier, J.M., Bui, A.Q., Yeung, E.C., Hashimoto, M., Fei, J., Harada, C.M., Munoz, M.D., Le, B.H., Drews, G.N., Brady, S.M., Goldberg, R.B., Harada, J.J. (2013) Comprehensive developmental profiles of gene activity in regions and subregions of the Arabidopsis seed. Proc. Natl. Acad. Sci. 110, E435-E444.
- Drews, G.N., Koltunow, A.M.G. (2011) The Female Gametophyte. The Arabidopsis Book 9, e0155
- Drews, G.N., Wang, D., Steffen, J.G., Schumaker, K.S., Yadegari, R. (2011) Identification of genes expressed in the angiosperm female gametophyte. Journal of Experimental Botany 62, 1593-1599.
- Wang, D., Zhang, C., Hearn, D.J., Kang, I.-H., Punwani, J.A., Skaggs, M.I., Drews, G.N., Schumaker, K.S., Yadegari, R. (2010) Identification of transcription-factor genes expressed in the Arabidopsis female gametophyte. BMC Plant Biology 10, 110.
- Le, B.H., Cheng, C., Bui, A.Q., Wagmaistera, J.A., Henrya, K.F., Pelletier, J., Kwong, L., Belmonte, M., Kirkbride, R., Horvath, S., Drews, G.N., Fischer, R.L., Okamuro, J.K., Harada, J.J., Goldberg, R.B. (2010) Global analysis of gene activity during Arabidopsis seed development and identification of seed-specific transcription factors. Proc. Natl. Acad. Sci.107, 8063-8070.
- Steffen, J.G., Kang, I.-H., Portereiko, M.F., Lloyd, A., Drews, G.N. (2008) AGL61 interacts with AGL80 and is required for central cell and endosperm development in Arabidopsis. Plant Physiology 148, 259-268.
- Kang, I.-H., Steffen, J.G., Portereiko, M.F., Lloyd, A., Drews, G.N. (2008) The AGL62 MADS domain protein regulates cellularization during endosperm development in Arabidopsis. Plant Cell 20, 635-647.
- Punwani, J.A., Rabiger, D.S., Lloyd, A., Drews, G.N. (2008) The MYB98 subcircuit of the synergid gene regulatory network includes genes directly and indirectly regulated by MYB98. Plant Journal 55, 406-414.
- Punwani, J.A., Drews, G.N. (2008) Development and function of the synergid cell. Sexual Plant Reproduction 21, 7-15.
- Punwani, J.A., Rabiger, D.S., Drews, G.N. (2007) MYB98 positively regulates a battery of synergid-expressed genes encoding filiform apparatus-localized proteins. Plant Cell 19, 2557-2568.
- Steffen, J.G., Kang, I.-H., Macfarlane, J., Drews, G.N. (2007) Identification of genes expressed in the Arabidopsis female gametophyte. Plant Journal 51, 281-292.
- Sandaklie-Nikolova, L., Palanivelu, R., King, E.J., Copenhaver, G.P., Drews, G.N. (2007) Synergid cell death in Arabidopsis is triggered following direct interaction with the pollen tube. Plant Physiology 144, 1753-1762.
- Coury, D.A., Zhang, C., Ko, A., Skaggs, M.I., Christensen, C.A., Drews, G.N., Feldmann, K.A., Yadegari, R. (2007) Segregation distortion in Arabidopsis gametophytic factor 1 (gfa1) mutants is caused by a deficiency of an essential RNA splicing factor. Sexual Plant Reproduction 20, 87-89.
- Portereiko, M.F., Lloyd, A., Steffen, J.G., Punwani, J.A., Otsuga, D., Drews, G.N. (2006) AGL80 is required for central cell and endosperm development in Arabidopsis. Plant Cell 18, 1862-1872.
- Portereiko, M.F., Sandaklie-Nikolova, L., Lloyd, A., Dever, C., Otsuga, D., Drews, G.N. (2006) NUCLEAR FUSION DEFECTIVE1 is required for karyogamy during fertilization and encodes the Arabidopsis RPL21M protein. Plant Physiology 141, 957-965.