Inter-Simple Sequence Repeats (ISSR), Microsatellite-Primed Genomic Profiling Using Universal Primers

Inter-simple sequence repeat (ISSR) markers are highly polymorphic, relatively easy to develop, and inexpensive compared to other methods and have numerous applications. Importantly, the same ISSR primers can potentially be used universally across plant phylogenetic diversity. The basic technique of ISSRs is flexible and can be modified with options for implementation for a broad range of projects and budgets. Ranked in increasing order of technical demand and costs, these are manual agarose and manual polyacrylamide with silver staining and automated using fluorescently labeled primers and capillary electrophoresis. Overall manual agarose-based ISSRs are a sound, safe, easy, and low-cost method for reliably inferring plant genetic diversity. Here, we provide detailed protocols to undertake this fingerprinting method and provide guidance to the literature for the many options available for this technique.

Multilocus Sequence Typing (MLST) and Random Polymorphic DNA (RAPD) Comparisons of Geographic Isolates of Neoparamoeba perurans, the Causative Agent of Amoebic Gill Disease

Neoparamoba perurans, is the aetiological agent of amoebic gill disease (AGD), a disease that affects farmed Atlantic salmon worldwide. Multilocus sequence typing (MLST) and Random Amplified Polymorphic DNA (RAPD) are PCR-based typing methods that allow for the highly reproducible genetic analysis of population structure within microbial species. To the best of our knowledge, this study represents the first use of these typing methods applied to N. perurans with the objective of distinguishing geographical isolates. These analyses were applied to a total of 16 isolates from Australia, Canada, Ireland, Scotland, Norway, and the USA. All the samples from Australia came from farm sites on the island state of Tasmania. Genetic polymorphism among isolates was more evident from the RAPD analysis compared to the MLST that used conserved housekeeping genes. Both techniques consistently identified that isolates of N. perurans from Tasmania, Australia were more similar to each other than to the isolates from other countries. While genetic differences were identified between geographical isolates, a BURST analysis provided no evidence of a founder genotype. This suggests that emerging outbreaks of AGD are not due to rapid translocation of this important salmonid pathogen from the same area.