IC4R001-Microarray-2011-221106719

Project Title

Distinct Gene Expression Profiles in Egg and Synergid Cells of Rice as Revealed by Cell Type-Specific Microarrays

The Background of This Project

• The molecular machineries underlying plant reproduction are becoming an area of active research. How- ever, the small number and inaccessibility of these cells have hampered molecular and genome-wide studies; thus, we know little about the molecular basis of cell specification, differentiation, and function in the female gametophyte. The identification of genes expressed in the female gametophyte is essential to understanding how female gametophyte cells become specified and acquire their unique features and functions. Previous research in this field has identified genes that are expressed in specific cells of the female gametophyte in various plant species. With the exception of Arabidopsis (Arabi- dopsis thaliana), microarray-based, comprehensive screens for genes exhibiting female gametophyte expression have never been done for plants.
• In rice, several methods for isolating egg cells have been reported. Most require a step to degrade the cell wall with catalytic enzymes, such as cellulase (Han et al., 1998; Zhao et al., 2000; Khalequzzaman and Haq, 2005). Egg and synergid cells can also be isolated from unfertilized ovaries by manual manipulation without using enzymes (Zhang et al., 1999; Uchiumi et al., 2006). In this project, the researchers collected a large number of rice egg and synergid cells by using manual manipulation instead of enzymes. The quality and quantity of the RNA obtained from the isolated cells were enough to per- form transcriptome analysis, and high-quality expression data for rice egg and synergid cells were obtained without cross-contamination. Direct comparisons between the data obtained and the transcriptomes of a variety of diploid tissues showed that the egg and synergid cell transcriptome was distinct. We also identified and characterized a large number of the genes expressed in rice egg and synergid cells. This study provides insights into the roles of genes ex- pressed in the female gametes before, during, and possibly after double fertilization.

Labs working on this Project

• Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo-ku, Tokyo 113–8657, Japan (T. Ohnishi, H. Takanashi, M.M., H. Takahashi, N.T.);
• Department of Life Sciences, Faculty of Agriculture, Meiji University, Kawasaki, Kanagawa 214–8571, Japan (S.K., K.Y.);
• Department of Biological Sciences, Tokyo Metropolitan University, Hachioji, Tokyo 192–0397, Japan (T. Okamoto);
• Genetic Strain Stock Center, National Institute of Genetics, Mishima, Shizuoka 411–8540, Japan (M.F., N.K.)

Corresponding Author

Nobuhiro Tsutsumi(email: atsutsu@mail.ecc.u-tokyo.ac.jp.)