Effects of mutual interaction of Laccaria laccata with Trichoderma harzianum and T. virens on the morphology of microtubules and mitochondria.

Organelles are known to respond to challenges caused by many stress factors. The morphology of the microtubular cytoskeleton and mitochondria during mutual interaction in coculture of Laccaria laccata with Trichoderma harzianum and T. virens were examined. Hyphae from the interaction region were sampled between 4 and 12 days of growth. Microtubules were labelled with a specific antibody and mitochondria with 3,3'-dihexyloxacarbocyanine iodide, and the organelles were examined microscopically. The morphology of microtubules and mitochondria were similar in all three fungi. Microtubules were arranged in long arrays parallel to the hyphal axis and mitochondria formed an interconnected network. In hyphae growing within the interaction zone, microtubules became wavy and eventually fragmented or depolymerised, and mitochondria also became fragmented. The effects were time-dependent. In general, the organelles of all three fungi were affected during the interaction, but L. laccata was affected the least and to the same extent by each of the saprotrophic fungi. The saprotrophic fungi were affected by L. laccata to a similar extent at 4 and 8 days of interaction. Our results suggest that the studied fungi antagonistically affect each other at the cellular level, although the mechanisms involved remain to be elucidated.