|Valent, B - KSU|
Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 2006
Publication Date: February 15, 2006
Citation: Jia, Y., Valent, B. 2006. Progress in developing rna markers for determining disease reactions in the rice blast system [abstract]. In: Rice Technical Working Group Meeting Proceedings, February 28 - March 1, 2006, Houston, Texas. 2006. CDROM. Technical Abstract: Hypersensitive cell death as indicated by the presence of autofluorescent materials, and rapid defense gene activations are two significant outcomes in rice plants during their resistant reaction to M. grisea infection. A resistant rice cultivar, Katy, and a Sekiguchi like-lesion mimic mutant of Katy (LmmKaty) were used to develop methods to detect the resistant response. Lesion mimic phenotype of LmmKaty was rapidly induced by virulent M. grisea isolates or by avirulent M. grisea isolates only at higher levels of inoculum. Autofluorescence was visible under ultraviolet light 24h post-inoculation in the incompatible interaction, whereas, autofluorescence was not evident in the compatible interaction. Autofluorescence was also observed in LmmKaty 20h post-inoculation indicating that rapid cell death is a mechanism bywhich LmmKaty restricts pathogen invasion. Doubled haploid lines, YT14 (containing the Pi-ta gene) and YT 16 (lacking the Pi-ta gene), were used for disease reactions and northern blot analysis. Plants were grown to the three leaf stage and were inoculated with M. grisea containing AVR-Pita at 5 X 10 6 spores /mL. Rapid accumulations of defense related (DR) gene transcripts, phenylalanine ammonia lyase and ß-glucanase, were observed beginning at 6 h and were obvious at 16 h and 24 h in an incompatible interaction. Rapid transcript accumulation of PR-1 and chitinase had occurred by 24h post-inoculation in an incompatible interaction. Accumulation of these transcripts was delayed in a compatible interaction. We suggest that the resistance gene in rice may recognize and actively respond to the pathogen 24h post-inoculation, and DR gene expression is a useful marker for rapid determination of the host reaction to M. grisea.