Host genotype may influence Misodendraceae infections

VIDAL-RUSSELL, R.

Carbondale, Illinois, EE.UU.

Congreso; Midwest Ecology and Evolution Conference.; 2005

In southern Argentina and Chile southern beech trees (Nothofagus) are infected by the endemic mistletoe Misodendrum. Infection intensity varies both within an individual host and at the population level, where patches of infected and non-infected trees are patchily distributed. Allozyme molecular markers were used to examine genetic differences between infected and non-infected trees at three field sites. Non-metric multidimensional scaling (NMDS) ordination was performed on the genotypes of 166 Nothofagus antarctica individuals (77 infected and 89 non-infected) using allele counts at 12 loci. The three field sites are distinguished in the ordination space. Two sites had a higher degree of infection of Misodendrum punctulatum and are in the same direction as the vector for this variable. The number of infections per tree is significantly correlated with both ordination axis. An analysis of similarity (ANOSIM) showed significant differences in genotype between infected and non-infected trees, but only for one of the two species of Misodendrum found on this host. The two sites with a higher degree of infection by M. punctulatum were not different, but were statistically distinguished from the third site. Allozyme variation may be due to infection of M. punctulatum, but other factors that influence the probability of being infected (such as differences in the morphotype of the host) may also contribute to the differences found. Thus, the genotype of the host does not confer resistance to Misodendraceae, but different morphotypes may increase or decrease the chance of being infected.