Lucas Lucena, Ana Benko-Iseppon, Bertram Brenig, Vasco Azevedo, Flávia Aburjaile, Elineide B Souza, Marco Aurélio Siqueira Gama

Phytopathology; 2023 Jan 26. doi: 10.1094/PHYTO-08-22-0279-A. 

Abstract

Cashew (Anacardium occidentale L.) angular leaf spot is caused by pigmented and non-pigmented strains of Xanthomonas citri pv. anacardii, which have been isolated from infected plants in Brazil. The disease symptoms may be observed in leaves, stems, and fruits. Given that infection in young fruits results in fruits unsuitable for commercialization, angular leaf spot represents a serious threat to the cashew crop in Brazil. Here, we report the genomic sequencing of seven pigmented strains of X. citri pv. anacardii, obtained from the leaves of cashew trees from São Paulo state, Brazil, in 2009. The construction of the libraries was carried out according to the manufacturer, and whole-genome sequencing was performed using the Illumina HiSeq 2500 platform. Genomes size, number of coding sequences, largest contig length, and N50 ranged from 4,996,984 to 5,003,485 bp, 4,621 to 4,643, 212,513 to 362,232, and 113,582 to 141,003. GC content and RNA numbers were 64.68% and 54 for all strains. ANIm and dDDH analyses showed values above 99.5% and 92.1% among these strains and the non-pigmented pathotype strain of X. citri pv. anacardii (IBSBF2579^PT). Maximum likelihood tree built with 2,708 core genes grouped all X. citri pv. anacardii strains in the same clade, with a 100% bootstrap. These resources will contribute in a relevant way to help understand the ecological, taxonomic, evolutionary, pathogenicity, and virulence aspects of X. citri pv. anacardii, which will be useful for the study and development of techniques for managing cashew angular leaf spot.

See https://pubmed.ncbi.nlm.nih.gov/36703497/

Fig 1. A, Heatmap representing the percentage of identity (ANIm) and dDDH between sequenced strains of Xanthomonas citri pv. anacardii (CCRMTAQ9, CCRMTAQ11, CCRMTAQ14, CCRMTAQ18, CCRMTAQ24, CCRMTAQ29 and CCRMTAQ31) and pathovars of X. citri. The upper triangle shows the ANIm values, and the lower triangle shows the dDDH values. B, Maximum-likelihood phylogenetic tree based on core genes of sequenced strains of X. citri pv. anacardii and pathovars of X. citri. Numbers at nodes are bootstrap values (>50%) from 1000 repetitions. Bar represents the expected number of substitutions per site. Superscripts following strain names: T = type strain of a species, and PT = pathotype strain of a pathovar.