INSTYTUT DENDROLOGII

Wojciech Szewczyk, Hanna Kwaśna, Jolanta Behnke-Borowczyk
Populations of Armillaria species in pine plantations in west-central Poland

Dendrobiology 2015, vol. 74: 95-108

http://dx.doi.org/10.12657/denbio.074.010

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Abstract: 

Two diploid isolates of Armillaria gallica and 143 diploid isolates of A. solidipes were obtained from 145 samples of rhizomorphs, fruit bodies and infected wood of sessile oak and Scots pines from 5–10-year-old Scots pine plantations in three Forest Districts located 100–350 km apart in west-central Poland. Based on pairings among the 145 isolates, 18 somatic compatibility groups (genets) of A. solidipes were distinguished in the three plantations. Sequencing of ITS1/2 rDNA of 18 isolates representing the 18 genets delineated four nuclear haplotypes. This suggests that many of the A. solidipes genets are closely related and were possibly established by sib-related basidiospores. With a few exceptions there was general geographical specialization of genets but not haplotypes. Geographical specialization of genets and the dominance of single haplotypes suggest that the A. solidipes population results from clonal rather than sexual reproduction. Sequencing of the ITS1/2 and IGS-1 rDNA showed small nucleotide diversity in ITS1/2 rDNA and much more diversity in IGS-1 rDNA of the isolates of A. solidipes studied. However, none of these regions has sufficient resolution for the clear differentiation of A. solidipes from A. borealis. The sequences of the EF 1-alpha gene showed high interspecific variability in Armillaria species and very low intraspecific variability in A. solidipes. This gene is the most appropriate for reliable identification of biological species and subgroups of Armillaria. Its application is the most useful in ecological and epidemiological studies of Armillaria.

Additional key words: Armillaria solidipes, EF-1 alpha gene, IGS, ITS, somatic incompatibility, population structure