Investigation on Tuberculina spp. parasite of Phakopsora pachyrhizi
1992
Prachoom Jutawantana | Udom Pupipat | Kiattisak Pothidee (Kasetsart Univ., Bangkok (Thailand). Corn and Sorghum Research Center)
Parasite fungi Tuberculina spp., was incidently found incidently found in the uredia of soybean rust fungi. When infected uredia were incubated at 20-22 deg C for 7 days in the dark, sporulation of more than 80 1/2 percent were obtained on the uredia. Spore masses appeared as whitish or creamy vigorous galls. The parasites were classified and designated into two groups as followed: a. Tuberculina sp. (I): sporodochium was brown and 150-250 micro m in diameter. Conidiophores were hyaline, filiform, 14-42*1-2.8 micro m and tip ended with sigle conidium. Conidia were hyaline, non-catenuate, elliptic-fusiform, 9.8-15.7*2.9-5.2 micro m (aver 13.5*4.3 micro m), mass of conidia was found in gelatinous matrix. b. Tuberculina sp. (II): sporodochium was brown and 150-250 micro m in diameter. Single conidiophore was grouped in densed mass, hyaline, cylindrical or filiform, 10.5-24.5*2.3-3 micro m Conidia was hyaline, ovate, 6.7-11.8*4.4-7.4 micro m (aver 5.9*9.1 micro m). Conidia were embeded in the gelatinous matrix and appeared as white or creamy horn. The parasite was able to grow on artificial media. The optimum temperature for development was 20-25 deg C and pH 4-10. Sporulation decreased upon subculturing. Poor germination were observed from conidia produced under both natural and artificial conditions. Histopathological studies of this fungus, parasitic on soybean rust revealed that Tuberculina spp. affected only the rust fungus, not the host plant tissue. Thus, this parasite should be called a "hyperparasite".
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