Comparisons of Pasteuria penetrans from Meloidogyne incognita with a related mycelial and endospore-forming bacterial parasite from Pratylenchus brachyurus
Sayre, RM.; Starr, MP.; Golden, AM.; Wergin, WP.; Endo, BY.
Proceedings of the Helminthological Society of Washington 551: 28-49
Major distinctions exist between members of the Pasteuria penetrans group occurring on the root-lesion nematode, Pratylenchus brachyurus, and the root-knot nematode, Meloidogyne incognita. These dissimilarities include highly restricted nematode host ranges, differences in the bacterial life stages in relation to those of the host nematodes, and disparities in ultrastructural morphology of their mature sporangia and endospores. The several stages of the bacterial parasite of the root-lesion nematode (RLP) occur in all the nematode's larval .mu.m in height. The endospores within the RLP sporangia are rhomboidal, and average 2.40 .+-. 0.24 .mu.m in diameter and 2.15 .+-. 0.19 .mu.m in height. The endospores within the RLP sporangia are ellipsoidal or almost spherical, narrowly elliptic in section, having axes averaging 1.08 .+-. 0.21 by 1.29 .+-. 0.14 .mu.m. By contrast, the mature bacterial stages from the root-knot nematode (RKP) occur only in the adutl female nematode and not in the larvae. The RKP sporangia are cup-shaped, and average 3.42 .+-. 0.18 .mu.m in diameter and 2.48 .+-. 0.22 .mu.m in height. The RKP endospores, also ellipsoidal but broadly elliptic in section, have axes averaging 1.10 .+-. 0.11 by 1.42 .+-. 0.12 .mu.m. These several morphological diversity was also evident from light-microscopic examination of members of the P. penetrans group occurring in archival nematode material (genera Dolichodorus, Heterodera, Hoplolaimus, Meloidogyne, Pratylenchus, Tylenchorhynchus, and Xiphenema) from the USDA Nematode Collection.