Morphological and molecular identification of Eutypa lata on grapevine in Serbia

During a survey from 2004 to 2016, symptoms of grapevine dieback were observed in six vineyards in Serbia. Symptoms initially appeared as small, chlorotic, and necrotic spots along the rim of the leaves, deformation of leafs, and the appearance of shortened shoots, often with the so-called zigzag internodes. Over time, partial or complete dying of the vines developed. Symptomatic samples were collected and submitted to laboratory analysis. Based on the morphological characterization, the isolated fungus was initially identified as belonging to Eutypa species. Pathogenicity tests showed that 47 selected isolates caused tissue necrosis around the site of inoculation, chlorosis, and deformation of the leaves, along with the appearance of tiny, necrotic spots on the periphery of the leaf that fall off over time. Inoculated cuttings were stunted, dwarf-like with zigzag internodes. Molecular identification was done with sequence and phylogenetic analysis of ITS, TUB, and RPB2 genomic regions. Based on the phylogenetic analysis, all isolated fungi were determined as Eutypa lata

A major invasion of transposable elements accounts for the large size of the Blumeria graminis f.sp. tritici genome

Powdery mildew of wheat (Triticum aestivum L.) is caused by the ascomycete fungus Blumeria graminis f.sp. tritici. Genomic approaches open new ways to study the biology of this obligate biotrophic pathogen. We started the analysis of the Bg tritici genome with the low-pass sequencing of its genome using the 454 technology and the construction of the first genomic bacterial artificial chromosome (BAC) library for this fungus. High-coverage contigs were assembled with the 454 reads. They allowed the characterization of 56 transposable elements and the establishment of the Blumeria repeat database. The BAC library contains 12,288 clones with an average insert size of 115 kb, which represents a maximum of 7.5-fold genome coverage. Sequencing of the BAC ends generated 12.6 Mb of random sequence representative of the genome. Analysis of BAC-end sequences revealed a massive invasion of transposable elements accounting for at least 85% of the genome. This explains the unusually large size of this genome which we estimate to be at least 174 Mb, based on a large-scale physical map constructed through the fingerprinting of the BAC library. Our study represents a crucial step in the perspective of the determination and study of the whole Bg tritici genome sequence