Corrigendum: Molecular Analysis of Bacterial Isolates From Necrotic Wheat Leaf Lesions Caused by Xanthomonas translucens, and Description of Three Putative Novel Species, Sphingomonas albertensis sp. nov., Pseudomonas triticumensis sp. nov. and Pseudomonas foliumensis sp. nov.

[This corrects the article DOI: 10.3389/fmicb.2021.666689.].

Hard to Kill: Inactivation of Plasmodiophora brassicae Resting Spores Using Chemical Disinfectants.

Biosafety practices, such as bioexclusion via sanitization, can prevent the spread of infectious soilborne threats such as the clubroot pathogen Plasmodiophora brassicae. Twenty-three chemical disinfectants were evaluated for efficacy against P. brassicae resting spores. Evans blue staining was used to directly measure the viability of P. brassicae resting spores after 20-min exposures to 10 concentrations of each of the 23 chemical disinfectants. Only nine disinfectants were capable of >95% inactivation, and only five were capable of inactivating >99% of resting spores. Bleach (sodium hypochlorite) and Spray Nine were the most effective disinfectants for inactivation of clubroot resting spores. AES 2500, SaniDate, and ethanol also inactivated >99% of resting spores but only at very high concentrations. A time course experiment showed that 10- to 12-min contact time was sufficient for ≥95% resting spore inactivation with Spray Nine and sodium hypochlorite, but ≥30-min contact was required for other disinfectants evaluated. These results will assist in guiding management recommendations for sanitization aimed at bioexclusion and biocontainment of P. brassicae.

Molecular Analysis of Bacterial Isolates From Necrotic Wheat Leaf Lesions Caused by Xanthomonas translucens, and Description of Three Putative Novel Species, Sphingomonas albertensis sp. nov., Pseudomonas triticumensis sp. nov. and Pseudomonas foliumensis sp. nov.

Xanthomonas translucens is the etiological agent of the wheat bacterial leaf streak (BLS) disease. The isolation of this pathogen is usually based on the Wilbrink's-boric acid-cephalexin semi-selective medium which eliminates 90% of other bacteria, some of which might be novel species. In our study, a general purpose nutrient agar was used to isolate 49 bacterial strains including X. translucens from necrotic wheat leaf tissues. Maximum likelihood cluster analysis of 16S rRNA sequences grouped the strains into 10 distinct genera. Pseudomonas (32.7%) and Pantoea (28.6%) were the dominant genera while Xanthomonas, Clavibacter and Curtobacterium had 8.2%, each. Erwinia and Sphingomonas had two strains, each. BLAST and phylogenetic analyses of multilocus sequence analysis (MLSA) of specific housekeeping genes taxonomically assigned all the strains to validly described bacterial species, except three strains (10L4B, 12L4D and 32L3A) of Pseudomonas and two (23L3C and 15L3B) of Sphingomonas. Strains 10L4B and12L4D had Pseudomonas caspiana as their closest known type strain while strain 32L3A was closest to Pseudomonas asturiensis. Sphingomonas sp. strains 23L3C and 15L3B were closest to S. faeni based on MLSA analysis. Our data on MLSA, whole genome-based cluster analysis, DNA-DNA hybridization and average nucleotide identity, matrix-assisted laser desorption/ionization-time-of-flight, chemotaxonomy and phenotype affirmed that these 5 strains constitute three novel lineages and are taxonomically described in this study. We propose the names, Sphingomonas albertensis sp. nov. (type strain 23L3CT = DOAB 1063T = CECT 30248T = LMG 32139T), Pseudomonas triticumensis sp. nov. (type strain 32L3AT = DOAB 1067T = CECT 30249T = LMG 32140T) and Pseudomonas foliumensis sp. nov. (type strain 10L4BT = DOAB 1069T = CECT 30250T = LMG 32142T). Comparative genomics of these novel species, relative to their closest type strains, revealed unique repertoires of core secretion systems and secondary metabolites/antibiotics. Also, the detection of CRISPR-Cas systems in the genomes of these novel species suggests an acquired mechanism for resistance against foreign mobile genetic elements. The results presented here revealed a cohabitation, within the BLS lesions, of diverse bacterial species, including novel lineages.

Analysis of Draft Genome Sequences of Two New Pantoea Strains Associated with Wheat Leaf Necrotic Tissues Caused by Xanthomonas translucens Reveals Distinct Species.

We report whole-genome sequences of two new Pantoea strains (DOAB1048 and DOAB1050) isolated from necrotic wheat leaves caused by Xanthomonas translucens The draft genome sequences of DOAB1048 and DOAB1050 consist of 52 and 57 scaffolds and have sizes of 4,795,525 bp and 4,962,883 bp with 4,418 and 4,517 coding sequences, respectively.

Improved Methods for Treatment of Phytopathogenic Biofilms: Metallic Compounds as Anti-Bacterial Coatings and Fungicide Tank-Mix Partners.

Fungi and bacteria cause disease issues in cultivated plants world-wide. In most cases, the fungi and bacteria colonize plant tissues as biofilms, which can be very challenging to destroy or eradicate. In this experiment, we employed a novel (biofilm) approach to crop disease management by evaluating the efficacies of six fungicides, and four silver-based compounds, versus biofilms formed by fungi and bacteria, respectively. The aim was to identify combinations of fungicides and metallic cations that showed potential to improve the control of white mold (WM), caused by the ascomycete fungus Sclerotinia sclerotiorum, and to evaluate novel high valency silver compounds as seed coatings to prevent biofilm formation of four bacterial blight pathogens on dry bean seeds. Our results confirmed that mature fungal biofilms were recalcitrant to inactivation by fungicides. When metallic cations were added to the fungicides, their efficacies were improved. Some improvements were statistically significant, with one combination (fluazinam + Cu2+) showing a synergistic effect. Additionally, coatings with silver compounds could reduce bacterial blight biofilms on dry bean seeds and oxysilver nitrate was the most potent inhibitor of bacterial blight.

Designation of a neotype for the Australian robber fly Ommatius dimidiatus Macquart, a new senior synonym of Ommatius pilosus White and Ommatius levis White (Diptera: Asilidae: Ommatiinae).

The holotype of Ommatius dimidiatus Macquart is confirmed as being lost and two specimens labeled as syntypes in the Muséum National d'Histoire Naturelle, Paris are considered not to have any type status. In accordance with Article 75 and complying with the qualifying conditions of Article 75.3 of the International Code of Zoological Nomenclature, a Tasmanian specimen of O. pilosus White, the only Ommatius Wiedemann species known to occur in Tasmania, is designated as a neotype of O. dimidiatus. Ommatius pilosus and O. levis White are confirmed as junior synonyms of O. dimidiatus.

Australian species of Ommatius Wiedemann (Diptera: Asilidae) with an anepimeral bristle.

The presence of an anepimeral bristle in Australian Ommatius Wiedemann species is newly recorded and descriptions of seven new species possessing this character are presented: O. aquilonaris sp. nov., O. burwelli sp. nov., O. imaginis sp. nov., O. limbatus sp. nov., O. melasmus sp. nov., O. musselbrookensis sp. nov. and O. radamnis sp. nov. All species occur in Queensland but O. melasmus sp. nov. also occurs in New South Wales and O. musselbrookensis sp. nov. also occurs in the Northern Territory. A key to separate the species is presented.

A new genus and two new species of soldier fly (Diptera: Stratiomyidae: Chiromyzinae) from Australia, one found infesting sugarcane in central Queensland.

Metridius nov. gen. and types species M. robertsoni nov. sp. with winged males and apterous females is described from adults and larvae found infesting sugarcane stools from near Mackay, central Queensland. A second new species, M. mcalpinei nov. sp., based only on males from near Sydney, New South Wales is also described. Notes on the biology of both species and an identification key to the genera of the subfamily Chiromyzinae and to the species are also given.

A new species of Neorhaphiomidas Norris (Diptera: Mydidae) from Queensland, Australia.

Neorhaphiomidas Norris, with 7 species, is an endemic genus and the only Australian representative of the mydid subfamily Megascelinae. The genus was for many years considered to be restricted to Western Australia but the range of the genus was extended to the eastern part of South Australia with Paramonov's (1961) description of N. inermis. The new species described here, the first record of the genus from Queensland, extends the known distribution of the genus some 1500 km to the north-east.