BALLISTOSPORE-FORMING YEASTS FOUND ON THE SURFACE OF THE JAPANESE RICE PLANT, ORYZA SATIVA L.

Abstract

Ninety-nine strains of ballistospore-forming yeasts were isolated from 43 samples of dead leaves and stems of the Japanese rice plant (Oryza sativa L.), and identified as belonging to the genera Bullera, Sporobolomyces, and Tilletiopsis. Thirty-one strains out of 55 of Bullera were assigned to B. alba (15 strains), B. crocea (13 strains), and B. piricola (3 strains). The remaining 24 strains of this genus were divided into 6 groups (species) which could not be assigned to any hitherto known species. Thirty-nine strains out of 41 of Sporobolomyces were assigned to S. roseus (35 strains) and S. shibatanus (4 strains). The remaining 2 strains of this genus were divided into 2 groups (species) which could not be assigned to any hitherto described species. Three strains of Tilletiopsis were assigned to T. lilacina. Of the 8 undescribed species, two were described respectively as the new species, B. oryzae and S. subbrunneus. Strains JCM 5281 and JCM 5278 respectively were designated as the types of the two species. Further study of the remaining 6 undescribed species is required before we determine their taxonomic position. The frequency of isolation of ballistospore- forming yeasts from Oryza sativa L. was 86%. Sporobolomyces roseus was found in the highest frequency, 72%, followed by Bullera sp. 1 (35%), B. crocea (30%), and B. alba (28%). The remaining species were found in relatively low frequencies below 9%.