|Alice Y. Cheung
Professor of Biochemistry and Molecular Biology, University of Massachusetts
Ph.D.: Yale University
Molecular and Biochemical Studies on Sexual Plant Reproduction
Sexual plant reproduction depends on intimate interactions between the male gametophyte (pollen) and a number of tissue and cell types in the female reproductive organ (pistil). Upon pollination, pollen grains have to deliver the male gametes to the egg cell for fertilization. This process, known as pollen tube growth, is highly efficient and is directional—pollen tubes always elongate from the proximal end of the pistil where pollination occurs to the distal end where the egg cells reside inside the ovary. The pollen tube growth process is dependent on the cellular activity within the pollen; female tissues through which pollen tubes elongate are believed to also provide biochemical and physical supports to attain the efficiency and the accuracy of the process. Biochemically, the female tissues may provide nutritional and directional guidance molecules for the pollen tubes.
Efforts in my laboratory are focused on identifying factors that play significant roles in pollination and fertilization, and on understanding how they interact with pollen tubes during these processes. Molecular, biochemical, classical, and reverse genetic approaches are employed in our studies in model plant systems such as tobacco and Arabidopsis. We have already identified and characterized a female tissue produced glycoprotein in tobacco that promotes pollen tube growth in vivo and in vitro and may have a role in pollen tube guidance. Additional molecules that are candidates for being major participants in the pollination and fertilization processes are being characterized for their role in sexual reproduction.
Nibau, C., Wu, H-M., Cheung, A. (2006) RAC/ROP GTPases: 'hubs' for signal integration and diversification in plants. Trends Plant Sci. June, [Epub ahead of print].
Li-zhen Tao, Alice Y. Cheung, Candida Nibau, and Hen-ming Wu . (2005). RAC GTPases in Tobacco and Arabidopsis Mediate Auxin-Induced Formation of Proteolytically Active Nuclear Protein Bodies That Contain AUX/IAA Proteins. Plant Cell 17: 2369-2383.
Barend H.J. de Graaf, Alice Y. Cheung, Tatyana Andreyeva, Kathryn Levasseur, Marcia Kieliszewski, and Hen-ming Wu (2005). Rab11 GTPase-Regulated Membrane Trafficking Is Crucial for Tip-Focused Pollen Tube Growth in Tobacco. Plant Cell 17: 2564-2579.
Cheung, A.Y., and Wu, H-M. (2004). Over-expression of an Arabidopsis Formin Stimulates Supernumerary Actin Cable Formation from Pollen Tube Cell Membrane. Plant Cell 16: 257-269.
Chen, C. Y-h., Cheung, A.Y. and Wu, H-M. (2003). Actin depolymerizing factor mediates Rac/Rop GTPase regulated pollen tube growth. Plant Cell 15: 237-249.
Cheung, A.Y., Chen, C., Tao,L-z., Andreyeva, T., Twell, D. and Wu, H-M. (2003). Regulation of pollen tube growth by Rac-like GTPases. J. Exp. Bot. 54: 73-81.
Tao, L-z., Cheung, A.Y., and Wu, H-M. (2002) Plant Rac-like GTPases are activated by auxin and mediate auxin responsive gene expression. Plant Cell 9: 2745-2760.
Chen, C., Wong, E., Vidali, L., Estavillo, A., Hepler, P.K., Wu, H-M., and Cheung, A.Y. (2002) The regulation of actin organization by actin depolymerizing factor (ADF) in elongating pollen tubes. Plant Cell 9: 2175-2190.
Cheung, A.Y., Chen, C., Glaven, R., Vidali, L., Hepler, P.K., and Wu, H-M. (2002) Rab2 regulate vesicular transport between endoplasmic reticulum and Golgi bodies and is important for pollen tube elongation. Plant Cell, 14: 945-962..
Chen, C., Wong, E., Vidali, L., Estavillo, A., Hepler, P.K., Wu, H-M., and Cheung, A.Y. (2002) The regulation of actin organization by actin depolymerizing factor (ADF) in elongating pollen tubes. Plant Cell, in press.
Wu, H.M., de Graaf, B., Mariani, C. and Cheung, A.Y. (2001) Structure and functions of hydroxyproline-rich glycoproteins in plant sexual reproductive tissues. CMLS, 58: 1418-1429.
Hepler, P.K., Vidali, L., and Cheung, A.Y. (2001) Polarized cell growth in higher plants. Ann. Rev. Cell and Dev. Biol. 17: 159-187.
Cheung, A.Y. (2001) Imaging elongating pollen tubes by the Green Fluorescence Protein. Sex Plant Reprod. 14: 9-14.
Cheung, A.Y. and Wu, H-M. 2001. Pollen tube guidance-right on target. Science 293: 1441-1442.
Cheung, A.Y. and Wu, H.M. (2000) Programmed cell death in plant reproductive development. Plant Mol. Biol. 44:267-281.
Wu, H.M. and Cheung, A.Y. (1998) Sexual Reproduction: sex differentiation, pollination and fertilization. Annual Plant Reviews (Sheffield Academic Press) Vol. 1. 181-222.
Cheung, A.Y. (1995) Pollen-pistil interactions in compatible pollination. Proc. Natl. Acad. Sci., USA. 92: 3077-3080.
Cheung, A.Y., Wang, H. and Wu, H-M. (1995) A floral transmitting tissue-specific glycoprotein attracts pollen tubes and stimulates their growth. Cell 82: 383-393.
Wu, H-M. and Cheung, A.Y. (1995) A pollen tube growth stimulatory glycoprotein is deglycosylated by pollen tubes and displays a glycosylation gradient in the flower. Cell 82: 395-403.