Prof. Watanabe started his research career by studying the multiplication process of tobacco mosaic virus (TMV) using protoplast system under the supervision of Prof. Yoshimi Okada. He obtained Ph.D. at the Department of Biophysics and Biochemistry, the Faculty of Science, the University of Tokyo. He continued research focusing on virus cell-to-cell movement in tissues serving as a research associate at the University of Tokyo and the Associate Professor at Teikyo University, Utsunomiya. Use of infectious viral clones from cDNA convinced him of the power of genetics and bioinformatics. During the stay as a guest scientist (Dr. Roger Beachy's lab) at the Scripps Research Institute, San Diego, he experienced marvelous potential of green fluorescent proteins. Since then, he has much interest in cell biology focusing on specific target proteins in host plants. He set up his own lab at the Department of Life Sciences since 1987. Plants are now known to have an ability to command small RNAs (siRNA or miRNA) to modulate exogenous, parasite and endogenous specific gene expressions to adapt to various environmental changes. Analysis of ARGONAUTE or DICER proteins, RNA degradation system during development stages and under stressed conditions using Arabidopsis thaliana are the main focus at present.