Variabilite genetique chez Ophiostoma piceae, agent de coloration de l'aubier, au Canada

Sapstain is defined as a blue or black discoloration of sapwood caused by penetrating fungi. These fungi do not cause decay but the timber will be downgraded, and its value will decrease. Thus, sapstain results in significant financial losses for lumber producers. Little is known about the identity, biology and ecology of the microorganisms involved in stain. In order to develop an integrated management or an environmentally benign technique against the stain, the biology of staining organisms needs to be well understood.

This study was designed to investigate the population diversity of the sapstain fungus found to be predominant in Canadian sawmills, using RAPD markers (Random Amplified Polymorphic DNA). Thus, a systematic survey was conducted at 7 selected sawmills in 6 Canadian provinces. The sampling included a wide range of important commercial wood species: balsam fir (Abies balsamea ), white spruce (Piceae glauca), black spruce ( P. mariana), Jack pine (Pinus banksiana) and lodgepole pine (P. contorta var. latifolia).

The first results confirmed that O. piceae was the most common species associated with sapstain. Analysis of RAPD markers revealed a high level of genetic variability in populations of this fungus in the six Canadians provinces. The analysis of population structure revealed that genetic diversity within populations accounted for most of the total genetic diversity. Thus, the analysis of genetic diversity of O. piceae in Canada did not reveal any clear trends in the distribution of genetic variability with regard to geographic origin or host species. (Abstract shortened by UMI.)