CHARACTERIZATION OF PASTEURIA ISOLATED FROM HETERODERA-CAJANI USING MORPHOLOGY, PATHOLOGY AND SEROLOGY OF ENDOSPORES

Pasteuria spp. are potentially useful natural parasites of nematodes. An isolate of Pasteuria, recovered from the pigeonpea cyst nematode, H eterodera cajani, was characterised using host range, spore morphometr ics, and serology. The spores of this isolate had a mean diameter of 2 .36 mu m, the smallest described so far on nematodes. Based on spore e ncumberance on nematode cuticle, Globodera rostochiensis, G. pallida, Heterodera glycines, H. trifolii, H. schachtii, and Rotylenchulus reni formis were hosts and H. carotae, H. galeopsidis, Meloidogyne arenaria , M. incognita, M. javanica, M. graminicola, M. oryzae, M. triticoryza e, M. sasseri, M. graminis, and M. naasi were non hosts. Spore attachm ent on the nematode body was random except on H. trifolii, where the s pores selectively attached to the head region. Marked heterogeneity in sport size and level of spore attachment within populations of nemato de species was observed. Variation in antigens present on the spore su rface was confirmed by differential recognition of spores by monoclona l and polyclonal antibodies and Western blot analysis. The parameters important in characterising species of Pasteuria are discussed in the light of the data reported. The results suggest that host range and sp ore morphometrics are not adequate for the characterisation of species .