title: Discovery of multiple IGS haplotypes within genotypes of Puccinia striiformis.
abstract: In a search for specific molecular markers for population analysis of Puccinia striiformis f. sp. tritici, the ribosomal DNA (rDNA) intergenic spacer (IGS) 1 region (rDNA-IGS1, between the 28S and the 5S rDNA genes) was amplified, cloned, and sequenced. It was found to exhibit multiple bands and length polymorphism. Surprisingly, single isolates were found to possess between three to five different IGS1 haplotypes. Bands were cloned and sequenced, and two highly variable regions (α and β) were found between conserved regions, with repeat units interspersed in both types of regions. There were 14 different repeat units, and these were sometimes grouped further into four combinations of repeat units, with a few individual nucleotides (A or C) inserted between the repeats. Among three geographically dispersed isolates, the variable region α was divided into eight types, and the variable region β was divided into two types based on repeat units. Most of the 14 repeat units were shared by the variable and the conserved regions. Among the three isolates, there were a total of 12 IGS1 haplotypes, but some of these were shared between isolates such that there were only eight unique haplotypes. The occurrence of multiple haplotypes within single isolates may be useful for analyzing the population structure, tracking the origin of annual epidemics and providing insights into evolutionary biology of this pathogen.
authors.affiliation: State Key Laboratory of Crop Stress Biology in Arid Areas and College of Plant Protection, Northwest A&F University, Yangling, Shaanxi, PR China.
authors.forename: Yanchun
authors.initials: Y
authors.lastname: Wang
authors.forename: Baojun
authors.initials: B
authors.lastname: Hao
authors.forename: Qiang
authors.initials: Q
authors.lastname: Zhang
authors.forename: Enlai
authors.initials: E
authors.lastname: Tuo
authors.forename: Guangyu
authors.initials: G
authors.lastname: Sun
authors.forename: Rong
authors.initials: R
authors.lastname: Zhang
authors.forename: Shelin
authors.initials: S
authors.lastname: Jin
authors.forename: Mingqi
authors.initials: M
authors.lastname: Zhu
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Tom
authors.initials: T
authors.lastname: Hsiang
mesh_terms: D001487:Basidiomycota / Q000145:classification* / Q000235:genetics*; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D005838:Genotype; D006239:Haplotypes; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA
chemical_list: D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer