A spontaneous Roller mutation in Bursaphelenchus xylophilus (Steiner & Buhrer, 1934) Nickle, 1970 (Nematoda: Aphelenchoididae)

Abstract

Summary The first spontaneous morphological/anatomical and behavioural mutation Bxy-rol(tom3) has been identified and characterised in the pine wood nematode, Bursaphelenchus xylophilus. The mutation is recessive to its wild-type counterpart. The mutant phenotype designated as Roller (Rol) is distinctive for the helical twist of the whole body around its longitudinal axis. The twist of the nematode body wall cuticle is followed by a similar twist of hypodermis, muscles and other organs and cuticular structures. These morphological and anatomical changes are responsible for the altered pattern of the nematode movement. Besides these changes, the Bxy-rol(tom3) mutation does not visibly affect any other essential character or function of B. xylophilus. Both wild-type and Rol nematodes present similar morphometrics, life cycle length, and reproductive potential. The Rol mutant easily cross-bred with individuals from any other tested strains/isolates of B. xylophilus and produced viable intra-specific hybrid offspring in vitro, on B. cinerea/potato dextrose agar plates. The mutants also seem to be well adapted to the nematode’s natural environment in pine wood. They dispersed inside pine seedlings, successfully mated, produced stable and fully viable offspring in this environment, and were as pathogenic to the host tree as the wild-type B. xylophilus. Potential of the characterised mutation as a marker for direct comparative study on strain/species reproductive compatibility, competition for space, food and vector insect, and for intra- and inter-specific hybridisation of B. xylophilus and B. mucronatus, is discussed.