Research Notes Changes in Protein Patterns Resulting from Infection of Rice Leaves with Xanthomonas oryzae pv. oryzae. Sang-Gu Kim. Department of Biology, Seoul National University, Seoul 151-742, Republic of Korea. Joo-Yeon Yoo. Department of Biology, Seoul National University, Seoul 151-742, Republic of Korea.. MPMI 5:356-360. Accepted 26 March 1992. Copyright 1992 The American Phytopathological Society.

Xanthomonas oryzae pv. oryzae causes bacterial leaf blight disease in rice (Oryza sativa). To understand symptom expression and host-regulated responses at the molecular level in infected rice plants, we analyzed changes in soluble protein patterns by two-dimensional polyacrylamide gel electrophoresis. Total soluble proteins were isolated from leaves over a time course of 4, 18, 24, 48, and 72 hr after bacterial infection. In host plants that responded to infection, 21 polypeptides showed changes. Ten polypeptides increased in response to infection. One polypeptide decreased during infection. A class of 10 new polypeptides was induced by infection. Particularly noteworthy were two polypeptides that dramatically increased in level during infection. These polypeptides had low molecular sizes (20 kDa) and acidic pI values characteristic of “pathogenesis-related” proteins (PR proteins), which play an important role in plant-microbe interactions.