Izabela Moura Duin

Bacterial leaf spot caused by Xanthomonas was reported in 2014 as a new disease of crape myrtle. Unfortunately, this foundational strain was lost, preventing further experimentation, sequencing of the genome, and phylogenetic analysis. This work describes a collection of Xanthomonas strains isolated from angular leaf spot lesions on crape myrtle in North Carolina from 2014 to 2023. This study includes full reference genomes as well as refulfillment of Koch’s postulates. Genomes were obtained with hybrid whole genome sequencing using Illumina and Nanopore and assembled to develop robust genomic resources for these disease-causing strains. The completed genomes support inclusion of the strains in the X. citri species group; however, both phylogenetic analysis and the identification of a novel plant host suggest the creation of the new pathovar Xanthomonas citri pv. lagerstroemium.

We performed genome sequencing and comparative analysis of Pantoea ananatis strains isolated from corn leaves expressing typical bacterial leaf streak (BLS) and maize white spot (MWS) symptoms to confirm bacterial identity and to understand the relationship among these strains and P. ananatis strains isolated from different plant hosts in Brazil. In pathogenicity tests, strains 4.2 and 13.3 isolated from symptomatic BLS leaves were non-pathogenic on corn. In contrast, strain B13 isolated from MWS-diseased leaf tissue caused symptoms typical of MWS. Our comparative analysis revealed that all three strains are very genetically similar. The G+C (%) content of strains 4.2 and 13.3 was 53.5%, while the B13 content was 53.7%. Average nucleotide identity (ANI) analysis showed that strains B13 and 13.3, B13 and 4.2, and 4.2 and 13.3 shared ANIs of 99.17%, 99.15% and 99.99%, respectively. Strains 13.3, B13, and 4.2 shared ~99% ANI with P. ananatis type strain LMG 2665. To the best of our knowledge, these are the first genome sequences of P. ananatis strains isolated from corn in Brazil.

We performed genome sequencing and comparative analysis of Pantoea ananatis strains isolated from corn leaves expressing typical bacterial leaf streak (BLS) and maize white spot (MWS) symptoms to confirm bacterial identity and to understand the relationship among these strains and P. ananatis strains isolated from different plant hosts in Brazil. In pathogenicity tests, strains 4.2 and 13.3 isolated from symptomatic BLS leaves were non-pathogenic on corn. In contrast, strain B13 isolated from MWS diseased leaf tissue caused symptoms typical of MWS. Our comparative analysis revealed that all three strains are very genetically similar. The G+C (%) content of the strains 4.2 and 13.3 was 53.5%, while B13 was 53.7%. Average nucleotide identity (ANI) analysis showed that strains B13 and 13.3, B13 and 4.2, and 4.2 and 13.3 shared ANIs of 99.17%, 99.15%, and 99.99%, respectively. Strains 13.3, B13 and 4.2 shared ~99% ANI with P. ananatis type strain LMG 2665. To our knowledge, these are the first genome sequences of P. ananatis strains isolated from corn in Brazil.

Sesame ( Sesamum indicum) is a specialty crop with increasing interest as an alternative, rotational crop for U.S. agricultural systems. This crop is susceptible to several pathogens, including Pseudomonas and Xanthomonas species. Two bacterial isolates were recently cultured from sesame in North Carolina symptomatic of bacterial spot and identified as Pseudomonas amygdali pv. sesami (Pas) and Xanthomonas sp. These isolates were used for hybrid whole-genome sequencing and assembly using Illumina and PacBio to develop robust genomic resources for these disease-causing strains. The results provide the most complete Pas genome available and placed the Xanthomonas sp. isolate into the X. arboricola species designation. Improved genomic resources for pathogens of sesame are needed to accurately detect, characterize, and employ timely management of the disease. [ ] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

The main objective of this study was to investigate the antimicrobial activity of three putative antagonist bacterial strains of Bacillus spp. against Xanthomonas vasicola pv. vasculorum (Xvv) and their potential to control bacterial leaf streak (BLS) of corn. Additionally, the study included investigations on the genome of one of these antagonist bacteria, such as genome sequencing and mining of genes involved in biofilm formation, swarming motility, and synthesis of secondary metabolites. The growth of Xvv was inhibited by both cell suspensions and cell-free supernatants of the bacterial strains LAFUEL 01, LAFUEL 02, and LAFUEL 03 in agar diffusion tests. All three antagonist strains significantly reduced the severity of BLS in the 3rd and 4th leaves of corn plants that were artificially inoculated at the V3 growth stage under greenhouse conditions. The 16S rRNA sequencing confirmed that the antagonistic bacterial strains belong to the genus Bacillus, with LAFUEL 03 having approximately 97% similarity to B. velezensis. B. velezensis LAFUEL 03 harbors genes related to the biosynthesis of secondary metabolites, biofilm formation/regulation, and swarming motility that enhances its potential for controlling BLS in corn and suggests a promising candidate for the development of a commercial biocontrol agent.

In July 2022, dark brown to black, angular, water-soaked lesions were observed on sesame leaves (Sesamum indicum L.) in a research plot established to assess yield potential for eight varieties at ...

We performed genome sequencing and comparative studies of Brazilian Pantoea ananatis strains isolated from diseased tissue of corn leaves with bacterial leaf streak (BLS) and maize white spot (MWS) to confirm the bacterial identity and to understand the relationship among these strains, as well as with three P. ananatis genomes from different plant hosts. In pathogenicity tests, the strains 4.2 and 13.3 isolated from BLS symptomatic leaves were not able to cause disease on corn. In contrast, the strain B13 isolated from MWS diseased leaf tissue caused typical symptoms of MWS. Our comparative analysis revealed that the genomes have several differences. The G+C (%) content of the strains 4.2 and 13.3 were 53.5% while for B13 was 53.7%. The average nucleotide identity (ANI) between B13 and 13.3, and B13 and 4.2 were 99.17 and 99.15%, respectively, and between 13.3 and 4.2 was 99.99%. To our knowledge, this is the first draft genome sequence of P. ananatis corn strains from Brazil.

Bacterial pustule caused by Xanthomonas citri pv. glycines (syn. X. axonopodis pv. glycines) is an important bacterial disease for soybean production worldwide. Currently, the planting of resistant soybean cultivars is the main measure for control of the disease. Therefore, the objectives of this study were to determine the aggressiveness of different X. citri pv. glycines isolates and to establish a new protocol to evaluate the reaction of soybean cultivars to bacterial pustule under greenhouse conditions. The molecular analysis based on the entire 16S rRNA gene sequence revealed that the isolates GDM 01, GDM 02, 333 and 87-2 belong to the X. citri pv. glycines pathovar with 100% identity with the pathotype strain K29 of this bacterium. Differences in aggressiveness were observed among the X. citri pv. glycines isolates. There were differences in the reaction of the soybean cultivars to bacterial pustule, depending on the inoculation method. The isolates 333, GDM 01 and GDM 02 were the most aggressive, while 87-2 and GDM 03 were the least aggressive ones. The best conditions for inoculation of the soybean plants were in the V3 vegetative growth stage with the inoculum concentration of 10⁸ CFU mL⁻¹, and moist chamber for 24 h before and after inoculation. Spraying without injury was the quickest and most practical inoculation method to screen soybean genotypes for resistance to bacterial pustule in breeding programs. Further, this method of inoculation closely simulates the natural bacterial infection under field conditions and produces typical symptoms of the disease. The standard brush inoculation method overestimated disease severity, so we do not recommend this method for the evaluation of bacterial pustule resistance in soybean breeding programs.