Analysis of Intraclonal Variation of Grape Phylloxera (Daktulosphaira vitifoliae Fitch) Using AFLP Fingerprinting

The asexual reproduction of higher organisms has become an important field of research in recent years and "natural" clones are associated as being 'genetically homogenous', comprising genetically identical individuals and thus displaying genetic fidelity. It seems improbable, that asexually reproducing species transfer exact replica of the maternal genome to their offspring for longer times. Genetic changes are likely to slip in, possibly due to genetic or epigenetic mutations, endosymbiotic activities or yet unknown mechanisms, but only few of them have been characterised to date. Grape phylloxera (Daktulosphaira vitifoliae Fitch, Hemiptera: Sternorrhyncha: Phylloxeridae) is suitable to examine the mechanisms of intraclonal genetic variation. In the present study, AFLP fingerprinting methods have been used in an attempt to uncover genetic diversity present within single founder lineages of grape phylloxera. Clonal lineages were monitored and mutations scored as polymorphisms among the founder individual and individuals of following generations. AFLP fingerprinting was employed to estimate the potential of genetic fingerprinting for the detection of genetic diversity present within single founder lineages of grape phylloxera (Daktulosphaira vitifoliae Fitch). Eight clonal lineages reproducing asexually throughout a minimum of 15 generations were monitored and mutations scored as polymorphisms comparing the founder individual to individuals of succeeding generations. Genetic variation was detected within all lineages, from early generations on. Six to 15 polymorphic loci were detected within the lineages, making up 4.3% of the total amount of genetic variation. The presence of contaminating extra-genomic sequences was excluded as a source of intraclonal variation by sequencing of polymorphic band confirming their phylloxerid origin.