First reported sexual recombination between Pyrenophora teres isolates from barley and barley grass.

Barley grass (Hordeum leporinum), which often occurs in proximity to commercial barley (Hordeum vulgare) cultivars, is an alternative host to Pyrenophora teres, an economically important pathogen causing net blotch in barley. This study is the first to report the sexual recombination of P. teres isolates collected from barley with those collected from barley grass. The sexual recombination between P. teres isolates from barley and barley grass was confirmed using a neighbour-net network and haploblock plots based on whole genome sequencing of seven progeny isolates. Pathogenicity assays revealed that P. teres isolates from barley grass were not host specific and could infect both barley and barley grass and the progeny isolates were virulent on commercially grown barley cultivars. Our results contradict previous population and pathogenicity studies of P. teres isolates obtained from barley and barley grass which have reported that the two populations are genetically distinct and host specific, suggesting that isolates collected from barley or barley grass could be two different entities. Despite the genetic divergence of P. teres isolates from barley and barley grass revealed through our phylogenomic analysis, there seems to be no complete host or reproductive separation between these populations. Therefore, there is a potential for generation of novel pathotypes through sexual recombination between P. teres isolates associated with barley and barley grass, with a risk of increased impacts on commercial barley cultivars that do not carry resistance to these pathotypes.

Whole-Genome Data from Curtobacterium flaccumfaciens pv. flaccumfaciens Strains Associated with Tan Spot of Mungbean and Soybean Reveal Diverse Plasmid Profiles.

Despite the substantial economic impact of Curtobacterium flaccumfaciens pv. flaccumfaciens on legume production worldwide, the genetic basis of its pathogenicity and potential host association is poorly understood. The production of high-quality reference genome assemblies of C. flaccumfaciens pv. flaccumfaciens strains associated with different hosts sheds light on the genetic basis of its pathogenic variability and host association. Moreover, the study of recent outbreaks of bacterial wilt and microevolution of the pathogen in Australia requires access to high-quality reference genomes that are sufficiently closely related to the population being studied within Australia. We provide the first genome assemblies of C. flaccumfaciens pv. flaccumfaciens strains associated with mungbean and soybean, which revealed high variability in their plasmid composition. The analysis of C. flaccumfaciens pv. flaccumfaciens genomes revealed an extensive suite of carbohydrate-active enzymes potentially associated with pathogenicity, including four carbohydrate esterases, 50 glycoside hydrolases, 23 glycosyl transferases, and a polysaccharide lyase. We also identified 11 serine peptidases, three of which were located within a linear plasmid, pCff119. These high-quality assemblies and annotations will provide a foundation for population genomics studies of C. flaccumfaciens pv. flaccumfaciens in Australia and for answering fundamental questions regarding pathogenicity factors and adaptation of C. flaccumfaciens pv. flaccumfaciens to various hosts worldwide and, at a broader scale, contribute to unraveling genomic features of gram-positive, xylem-inhabiting bacterial pathogens.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Whole genomes redefine the mutational landscape of pancreatic cancer.

Pancreatic cancer remains one of the most lethal of malignancies and a major health burden. We performed whole-genome sequencing and copy number variation (CNV) analysis of 100 pancreatic ductal adenocarcinomas (PDACs). Chromosomal rearrangements leading to gene disruption were prevalent, affecting genes known to be important in pancreatic cancer (TP53, SMAD4, CDKN2A, ARID1A and ROBO2) and new candidate drivers of pancreatic carcinogenesis (KDM6A and PREX2). Patterns of structural variation (variation in chromosomal structure) classified PDACs into 4 subtypes with potential clinical utility: the subtypes were termed stable, locally rearranged, scattered and unstable. A significant proportion harboured focal amplifications, many of which contained druggable oncogenes (ERBB2, MET, FGFR1, CDK6, PIK3R3 and PIK3CA), but at low individual patient prevalence. Genomic instability co-segregated with inactivation of DNA maintenance genes (BRCA1, BRCA2 or PALB2) and a mutational signature of DNA damage repair deficiency. Of 8 patients who received platinum therapy, 4 of 5 individuals with these measures of defective DNA maintenance responded.

Draft Genome Resource for Macrophomina phaseolina Associated With Charcoal Rot in Sorghum.

Macrophomina phaseolina is a soil-borne phytopathogenic fungus that causes charcoal rot in several plant species, including sorghum. We constructed a draft genome of M. phaseolina isolate BRIP 70780a from sorghum, using long-read native DNA from MinION sequencing, which was error-corrected using short-read Illumina MiSeq reads. The draft genome, consisting of 22 contigs with an N50 of 4,257,441 bp, 99.3% complete benchmarking universal single-copy orthologs, and 14,471 genes, is a valuable resource to aid future studies in population genomics and molecular diagnostic marker development for rapid detection of the pathogen.

Rare Pyrenophora teres Hybridization Events Revealed by Development of Sequence-Specific PCR Markers.

Pyrenophora teres f. teres and P. teres f. maculata cause net form and spot form, respectively, of net blotch on barley (Hordeum vulgare). The two forms reproduce sexually, producing hybrids with genetic and pathogenic variability. Phenotypic identification of hybrids is challenging because lesions induced by hybrids on host plants resemble lesions induced by either P. teres f. teres or P. teres f. maculata. In this study, 12 sequence-specific polymerase chain reaction markers were developed based on expressed regions spread across the genome. The primers were validated using 210 P. teres isolates, 2 putative field hybrids (WAC10721 and SNB172), 50 laboratory-produced hybrids, and 7 isolates collected from barley grass (H. leporinum). The sequence-specific markers confirmed isolate WAC10721 as a hybrid. Only four P. teres f. teres markers amplified on DNA of barley grass isolates. Amplified fragment length polymorphism markers suggested that P. teres barley grass isolates are genetically different from P. teres barley isolates and that the second putative hybrid (SNB172) is a barley grass isolate. We developed a suite of markers which clearly distinguish the two forms of P. teres and enable unambiguous identification of hybrids.

The First Annotated Genome Assembly of Macrophomina tecta Associated with Charcoal Rot of Sorghum.

Charcoal rot is an important soilborne disease caused by a range of Macrophomina species, which affects a broad range of commercially important crops worldwide. Even though Macrophomina species are fungal pathogens of substantial economic importance, their mechanism of pathogenicity and host spectrum are poorly understood. There is an urgent need to better understand the biology, epidemiology, and evolution of Macrophomina species, which, in turn, will aid in improving charcoal rot management strategies. Here, we present the first high-quality genome assembly and annotation of Macrophomina tecta strain BRIP 70781 associated with charcoal rot symptoms on sorghum. Hybrid assembly integrating long reads generated by Oxford Nanopore Technology and short Illumina paired-end reads resulted in 43 contigs with a total assembly size of ∼54 Mb, and an N50 of 3.4 Mb. In total, 12,926 protein-coding genes and 7,036 repeats were predicted. Genome comparisons detected accumulation of DNA transposons in Macrophomina species associated with sorghum. The first reference genome of M. tecta generated in this study will contribute to more comparative and population genomics studies of Macrophomina species.

The curation of genetic variants: difficulties and possible solutions.

The curation of genetic variants from biomedical articles is required for various clinical and research purposes. Nowadays, establishment of variant databases that include overall information about variants is becoming quite popular. These databases have immense utility, serving as a user-friendly information storehouse of variants for information seekers. While manual curation is the gold standard method for curation of variants, it can turn out to be time-consuming on a large scale thus necessitating the need for automation. Curation of variants described in biomedical literature may not be straightforward mainly due to various nomenclature and expression issues. Though current trends in paper writing on variants is inclined to the standard nomenclature such that variants can easily be retrieved, we have a massive store of variants in the literature that are present as non-standard names and the online search engines that are predominantly used may not be capable of finding them. For effective curation of variants, knowledge about the overall process of curation, nature and types of difficulties in curation, and ways to tackle the difficulties during the task are crucial. Only by effective curation, can variants be correctly interpreted. This paper presents the process and difficulties of curation of genetic variants with possible solutions and suggestions from our work experience in the field including literature support. The paper also highlights aspects of interpretation of genetic variants and the importance of writing papers on variants following standard and retrievable methods.