Comparative genomics of a plant-pathogenic fungus, pyrenophora tritici-repentis, reveals transduplication and the impact of repeat elements on pathogenicity and population divergence

Pyrenophora tritici-repentis is a necrotrophic fungus causal to the disease tan spot of wheat, whose contribution to crop loss has increased significantly during the last few decades. Pathogenicity by this fungus is attributed to the production of host-selective toxins (HST), which are recognized by their host in a genotype-specific manner. To better understand the mechanisms that have led to the increase in disease incidence related to this pathogen, we sequenced the genomes of three P. tritici-repentis isolates. A pathogenic isolate that produces two known HSTs was used to assemble a reference nuclear genome of approximately 40 Mb composed of 11 chromosomes that encode 12,141 predicted genes. Comparison of the reference genome with those of a pathogenic isolate that produces a third HST, and a nonpathogenic isolate, showed the nonpathogen genome to be more diverged than those of the two pathogens. Examination of gene-coding regions has provided candidate pathogen-specific proteins and revealed gene families that may play a role in a necrotrophic lifestyle. Analysis of transposable elements suggests that their presence in the genome of pathogenic isolates contributes to the creation of novel genes, effector diversification, possible horizontal gene transfer events, identified copy number variation, and the first example of transduplication by DNA transposable elements in fungi.Overall, comparative analysis of these genomes provides evidence that pathogenicity in this species arose through an influx of transposable elements, which created a genetically flexible landscape that can easily respond to environmental changes

MORPHOLOGICAL AND MOLECULAR EVALUATION OF THE FAR EAST FRUIT GENETIC RESOURCES OF <i> LONICERA CAERULEA </i> L.

Field studies of honeysuckle (Lonicera caerulea L. s.l.) and material for investigation (91 herbarium accessions; 20 scion samples; and fruits for detailed morphological description, organoleptic and molecular analyses) have been collected in the north-eastern part of the area of honeysuckle distribution, in Kamchatka and Sakhalin regions. All coenopopulations have been characterized ecologically, geobotanically, and phytosociologically. Factors threatening natural coenopopulations have been estimated, and these data preconditioned recommendations for honeysuckle in situ conservation. Fruits of 20 Russian honeysuckle cultivars have been included in comparative molecular assessment together with fruits from natural ecotypes. As a result of AFLP analysis, all investigated material was divided into three groups: two groups include samples L. caerulea, collected in Kamchatka, and the majority of the investigated honeysuckle cultivated forms, while the third group unites only genotypes of the sakhalin plants

DNA markers for identification of Pyrenophora tritici-repentis and detection of genetic diversity among its isolates

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