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BackgroundSpecies identification is essential for controlling disease, understanding epidemiology, and to guide the implementation of phytosanitary measures against fungi from the genus Diaporthe. Accurate Diaporthe species separation requires using multi-loci phylogenies. However, defining the optimal set of loci that can be used for species identification is still an open problem.MethodsHere we addressed that problem by identifying five loci that have been sequenced in 142 Diaporthe isolates representing 96 species: TEF1, TUB, CAL, HIS and ITS. We then used every possible combination of those loci to build, analyse, and compare phylogenetic trees.ResultsAs expected, species separation is better when all five loci are simultaneously used to build the phylogeny of the isolates. However, removing the ITS locus has little effect on reconstructed phylogenies, identifying the TEF1-TUB-CAL-HIS 4-loci tree as almost equivalent to the 5-loci tree. We further identify the best 3-loci, 2-loci, and 1-locus trees that should be used for species separation in the genus.DiscussionOur results question the current use of the ITS locus for DNA barcoding in the genus Diaporthe and suggest that TEF1 might be a better choice if one locus barcoding needs to be done.

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The epidemic situation of Moko disease-causing strains in Latin America and Brazil is unclear. Thirty-seven Ralstonia solanacearum strains from Brazil that cause the Moko disease on banana and heliconia plants were sampled and phylogenetically typed using the endoglucanase (egl) and DNA repair (mutS) genes according to the phylotype and sequevar classification. All of the strains belonged to phylotype II and a portion of the strains was typed as the Moko disease-related sequevars IIA-6 and IIA-24. Nevertheless, two unsuspected sequevars also harbored the Moko disease-causing strains IIA-41 and IIB-25, and a new sequevar was described and named IIA-53. All of the strains were pathogenic to banana and some of the strains of sequevars IIA-6, IIA-24, and IIA-41 were also pathogenic to tomato. The Moko disease-causing strains from sequevar IIB-25 were pathogenic to potato but not to tomato. These results highlight the high diversity of strains of Moko in Brazil, reinforce the efficiency of the egl gene to reveal relationships among these strains, and contribute to a better understanding of the diversity of paraphyletic Moko disease-causing strains of the R. solanacearum species complex, where the following seven distinct genetic clusters have been described: IIA-6, IIA-24, IIA-41, IIA-53, IIB-3, IIB-4, and IIB-25.

Peach tree diseases have a variety of symptoms and causes. Only Botryosphaeriaceae taxa have been reported in association with peach trees in Chinese peach orchards. This study aims to identify and characterize Diaporthe species associated with peach trees in Jinshui Experimental Orchard in Hubei Academy of Agriculture Sciences, Hubei Province, China. The fungi were isolated from diseased peach trunks and shoots showing exudates. Fungal identification was accomplished using a combination of morphological and pathogenic characteristics together with phylogenetic analyses based on internal transcribed spacer (ITS), partial translation elongation factor 1-α (EF1-α), β-tubulin (BT) and calmodulin (CAL) sequences. A total of 48 Diaporthe isolates were obtained from 62 diseased samples and most isolates were identified as Diaporthe eres (69 %), followed by D. momicola sp. nov (12.5 %), D. pescicola sp. nov. (10 %) and D. taoicola sp. nov. (8.5 %). All identified species were able to cause necrotic lesions at different levels of severity when inoculated into detached peach shoots

Grapevine bacterial canker, which is caused by Xanthomonas campestris pv. viticola, is one of the most important grapevine diseases in the northeastern region of Brazil. This disease causes severe damage and represents a high potential risk to the development of Brazilian viticulture. In turn, pigmented isolates pathogenic to cashew plant, making cashew fruit unfit for sale, also have been detected in Northeastern Brazil. Given that the taxonomic position of these bacteria is unclear, the multilocus sequence analysis (MLSA) technique, average nucleotide identity (ANI) values and tetranucleotide frequency correlation coefficients (TETRA) were used to analyze their phylogenetic relationship in relation to other Xanthomonas species. X. campestris pv. viticola was closely related to X. citri pv. mangiferaeindicae (repetitive-polymerase chain reaction [rep-PCR], MLSA, and ANI) and X. citri subsp. citri (MLSA and ANI). Pigmented isolates pathogenic to cashew plant were closely related to X. citri pv. anacardii (rep-PCR, MLSA, ANI, and TETRA). The results obtained in this study support the emendation of the description of X. citri pv. anacardii to include pigmented isolates of Xanthomonas pathogenic to cashew plant. In addition, the reclassification of X. campestris pv. viticola as X. citri pv. viticola comb. nov. is suggested.