Abstract:
Lecanosticta acicola is an ascomycete that causes brown spot needle blight of pine species
in many regions of the world. This pathogen is responsible for a major disease of Pinus
palustris in the USA and is a quarantine organism in Europe. In order to study the genetic
diversity and patterns of spread of L. acicola, eleven microsatellite markers and two
mating type markers were developed. An enrichment protocol was used to isolate
microsatellite-rich DNA regions and 18 primer pairs were designed to flank these regions,
of which eleven were polymorphic. A total of 93 alleles were obtained across all loci from
forty isolates of L. acicola from the USA with an allelic diversity range of 0.095 to 0.931
per locus. Cross-species amplification with some of the markers was obtained with L.
gloeospora, L. guatemalensis and Dothistroma septosporum, but not with D. pini. Mating
type (MAT) markers amplifying both idiomorphs were also developed to determine mating
type distribution in populations. These markers were designed based on alignments of both
idiomorphs of nine closely related plant pathogens and a protocol for multiplex PCR
amplification of the MAT loci was optimised. The MAT markers are not species specific
and also amplify the MAT loci in Dothistroma septosporum, D. pini, L. gloeospora and L.
guatemalensis. Both types of genetic markers developed in this study will be valuable for
future investigations of the population structure, genetic diversity and invasion history of
L. acicola on a global scale.
