Verticillium dahliae is a soilborne pathogen that causes wilt diseases of many plant species. Isolates of V. dahliae can be classified into pathotypes, such as the tomato pathotype and sweet pepper pathotype, based on their pathogenicity to each plant. In Japan, only a few isolates that are pathogenic on both tomato and sweet pepper, (tomato-sweet pepper pathotype) have been identified. Our results of RAPD analyses suggested that the tomato-sweet pepper pathotype was genetically related to both the tomato and sweet pepper pathotypes. Therefore, we tested for genetic recombination between these pathotypes of asexual fungus V. dahliae. Conidia were collected from the cocultured nit1 mutant of tomato pathotype and a NitM mutant of sweet pepper pathotype. After culturing these conidia on minimal media, we obtained 22 prototrophic isolates. One of these prototrophic isolates, Prt-D, was pathogenic on both tomato and sweet pepper. Furthermore, RAPD analyses indicated that Prt-D was a genetic hybrid of tomato and sweet pepper pathotype. These results suggest that the host range of V. dahliae may be expanded by genetic recombination between these pathotypes.
The protein content in rice grains is negatively correlated with eating quality. Protein content of the grains can be estimated using the normalized difference vegetation index (NDVI) with satellite or airborne sensor. The relationship between NDVI and panicle blast severity was examined to assess the effect of severity on the NDVI. As severity increased, NDVI estimated with both a radiometer and an airborne hyper-spectral sensor decreased. Severity of panicle blast must be assessed with the NDVI before estimating the protein of the grain.