Cryptosporiopsis species isolated from the roots of aspen in central Alberta:: identification, morphology, and interactions with the host, in vitro

Cryptosporiopsis Bubak & Kabat isolates were obtained for the first time from roots of apparently healthy aspen seedlings in Alberta. These isolates were similar in all the major morphological features previously used to separate Cryptosporiopsis species, but sequencing data of the ITS1-5.8S-ITS2 region indicated that they were separated into two groups, one belonging to Cryptosporiopsisaericae Sigler and the other to Cryptosporiopsisaradicicola Kowalski & Bartnik. Scanning electron microscopy of ex-type cultures and selected isolates from aspen roots revealed that C.aericae and C.aradicicola differed in morphogenesis and structure of conidiomata: those of C.aericae were either synnematous or sporodochial, whereas those of C.aradicicola possessed a peridium-like mycelial envelope bearing amorphous adhesive material. Phialides in the hymenium of C.aradicicola were also embedded in amorphous matrix material but such material was absent in C.aericae. Microscopic examination of artificially inoculated aspen roots indicated that both species are endophytes of the host. Hyphal penetration by C.aericae was only occasional and confined to the host epidermis, whereas C.aradicicola was more aggressive and its hyphal ingress extended to the cortical region.