Suppression of Pisatin and Phenylalanine Ammonia LyasemRNA in a Compatible Interaction between Pisum sativum L. cv. Midoriusui and Pseudomonas syringae pv. pisi

Abstract

The accumulation of pisatin in epicotyl tissues of Pisum sativum L. cv. Midoriusui inoculated with compatible races of Pseudomonas syringae pv. pisi (P. pisi) was significantly suppressed comparing to that by the inoculation with a incompatible race. This was reflected by the suppression of the accumulation of phenylalanine ammonia-lyase (PAL)-mRNA in the inoculated tissues. Low molecular mass (MW<ca. 10, 000 Da) substances secreted in the culture filtrates from the compatible race of P. pisi exhibited the suppression of pisatin accumulation, whereas those from the incompatible race did not. The relationship between the suppression of host defense reactions and the specificity of race-cultivar in bacterial disease is discussed.