HomePlant DiseaseVol. 106, No. 6First Report of Podosphaera aphanis Causing Powdery Mildew on Wild Blackberry Species (Rubus Species) in Mexico PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Podosphaera aphanis Causing Powdery Mildew on Wild Blackberry Species (Rubus Species) in MexicoA. R. Solano-Báez, S. G. Leyva-Mir, M. Camacho-Tapia, A. D. Victoria-Arellano, G. Rodríguez-Bautista, C. S. Sánchez-Rosas, and G. Márquez-LiconaA. R. Solano-Báezhttps://orcid.org/0000-0001-9518-5455Universidad Autónoma de Occidente, Maestría en Fitopatología y Medio Ambiente, 81217, Ahome, Sinaloa, México, S. G. Leyva-Mirhttps://orcid.org/0000-0003-1831-2806Universidad Autónoma Chapingo, Departamento de Parasitología Agrícola, Texcoco, 56230, Estado de México, México, M. Camacho-TapiaUniversidad Autónoma Chapingo, Laboratorio Nacional de Investigación y Servicio Agroalimentario y Forestal, Texcoco, 56230, Estado de México, México, A. D. Victoria-Arellanohttps://orcid.org/0000-0002-0583-3357Laboratório de Interação Planta Patógeno, Faculdade de Agronomia Eliseu Maciel, Universidade Federal de Pelotas, Departamento de Fitossanidade, Pelotas, 96010-610, Rio Grande do Sul, Brazil, G. Rodríguez-BautistaUniversidad de Guadalajara, Centro Universitario de la Costa Sur, Autlán, 48900, Jalisco, México, C. S. Sánchez-RosasUniversidad Autónoma Chapingo, Departamento de Parasitología Agrícola, Texcoco, 56230, Estado de México, México, and G. Márquez-Licona†Corresponding author: G. Márquez-Licona; E-mail Address: gmarquezl@ipn.mxhttps://orcid.org/0000-0002-3981-8585Instituto Politécnico Nacional, Centro de Desarrollo de Productos Bióticos, 62731, Yautepec, Morelos, México AffiliationsAuthors and Affiliations A. R. Solano-Báez1 S. G. Leyva-Mir2 M. Camacho-Tapia3 A. D. Victoria-Arellano4 G. Rodríguez-Bautista5 C. S. Sánchez-Rosas2 G. Márquez-Licona6 † 1Universidad Autónoma de Occidente, Maestría en Fitopatología y Medio Ambiente, 81217, Ahome, Sinaloa, México 2Universidad Autónoma Chapingo, Departamento de Parasitología Agrícola, Texcoco, 56230, Estado de México, México 3Universidad Autónoma Chapingo, Laboratorio Nacional de Investigación y Servicio Agroalimentario y Forestal, Texcoco, 56230, Estado de México, México 4Laboratório de Interação Planta Patógeno, Faculdade de Agronomia Eliseu Maciel, Universidade Federal de Pelotas, Departamento de Fitossanidade, Pelotas, 96010-610, Rio Grande do Sul, Brazil 5Universidad de Guadalajara, Centro Universitario de la Costa Sur, Autlán, 48900, Jalisco, México 6Instituto Politécnico Nacional, Centro de Desarrollo de Productos Bióticos, 62731, Yautepec, Morelos, México Published Online:13 Apr 2022https://doi.org/10.1094/PDIS-05-21-0932-PDNAboutSectionsView articlePDFSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleWild blackberry species (Rubus spp. L.; Rosaceae) represents an invaluable source of genes for the generation of new varieties, but they also serve as a primary source of disease inoculum. During April of 2020, symptoms of powdery mildew were observed on four populations of wild blackberry species located in the states of Chiapas (16°59′11″N, 92°59′07″W; 16°47′08″N, 92°31′05″W) and Michoacán (19°37′17″N, 100°08′59″W; 19°29′25″N, 101°32′54″W), Mexico. Signs of the pathogen were white powdery masses mainly on the top of new shoots. Symptoms included yellowing, necrosis, and early defoliation of the plants. Hyphae were thin-walled, hyaline, smooth, and 4.0 to 9.0 mm wide. Appressoria were indistinct to nipple-shaped. Conidiophores (n = 30, 75 to 225 × 10.5 to 13.5 μm) were straight and unbranched with cylindrical foot cells (n = 30, 31.5 to 158 × 8 to 13.5 μm), straight, somewhat widening upwards, followed by one to three shorter cells. Conidia (n = 100; 25.5 to 38.5 × 9.5 to 22.5 μm) were catenulate, ellipsoid-ovoid to doliiform, containing fibrosin bodies (in 3% KOH). Germ tubes (n = 30, 13.5 to 40.5 × 4.5 μm) emerged laterally and were unbranched with slightly swollen tips. Chasmothecia were not found. Morphological characters of the fungus in all samples corresponded to the previous descriptions of Podosphaera aphanis by Braun and Cook (2012) and Stevanović et al. (2021). Voucher specimens were deposited in the Department of Agricultural Parasitology Herbarium at the Chapingo Autonomous University under accessions UACH421, UACH423, UACH425, and UACH426. To confirm the species identification, the internal transcribed spacer of one sample was amplified using the primers ITS5 (White et al. 1990) and P3 (Kusaba and Tsuge 1995) and sequenced. The sequence was deposited in GenBank (accession no. MW988591). A phylogenetic analysis using Bayesian inference and maximum likelihood was performed (Hernández-Restrepo et al. 2018) and included other Podosphaera species (Takamatsu et al. 2010). The sequence from the isolate UACH426 clustered with the strain MUMH1871 of P. aphanis, forming a definite clade, and remained as a sister taxon of P. pannosa. Pathogenicity was verified through inoculation by gently dusting conidia from one powdery mildew patch onto leaves of five healthy blackberry plants of each species. The same number of noninoculated plants served as controls. All plants were maintained in a greenhouse at 25 to 30°C with 75% relative humidity. All inoculated plants developed powdery mildew symptoms after 12 days, whereas no symptoms were observed on noninoculated plants. The fungus recovered from the inoculated plants was morphologically identical to that originally observed on diseased blackberry plants, demonstrating the pathogenicity of the fungus. Based on morphological data and phylogenetic analysis, the fungus was identified as P. aphanis. This fungus has been reported to cause powdery mildew on blackberry plants in Serbia (Stevanović et al. 2021). This is the first report of P. aphanis causing powdery mildew on wild blackberry species in Mexico according to Farr and Rossman (2021). The primary source of inoculum of powdery mildew for commercial plantings is wild blackberry plants from noncultivated areas and may warrant control of wild populations.The author(s) declare no conflict of interest.References:Braun, U., and Cook, R. T. A. 2012. Taxonomic Manual of the Erysiphales (Powdery Mildews). CBS Biodiversity Series No. 11. CBS, Utrecht, the Netherlands. Google ScholarFarr, D. F., and Rossman, A. Y. 2021. Fungal Databases, Syst. Mycol. Microbiol. Lab., ARS, USDA. Retrieved February 3, 2021, from https://nt.ars-grin.gov/fungaldatabases/ Google ScholarHernández-Restrepo, M., et al. 2018. Persoonia 41:71. https://doi.org/10.3767/persoonia.2018.41.05 Crossref, ISI, Google ScholarKusaba, M., and Tsuge, T. 1995. Curr. Genet. 28:491. https://doi.org/10.1007/BF00310821 Crossref, ISI, Google ScholarStevanović, M., et al. 2021. Plant Dis. 105:503. https://doi.org/10.1094/PDIS-06-20-1171-PDN Link, ISI, Google ScholarTakamatsu, S., et al. 2010. Persoonia 24:38. https://doi.org/10.3767/003158510X494596 Crossref, ISI, Google ScholarWhite, T. J., et al. 1990. Page 315 in: PCR Protocols: A Guide to Methods and Applications. Academic Press, San Diego, CA. Google ScholarFunding: This research was financially supported by the Secretary of Research and Graduate of the National Polytechnic Institute (Instituto Politécnico Nacional), project SIP20201117.The author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 106, No. 6 June 2022SubscribeISSN:0191-2917e-ISSN:1943-7692 Download Metrics Downloaded 562 times Article History Issue Date: 2 Jun 2022Published: 13 Apr 2022First Look: 20 Jul 2021Accepted: 18 Jul 2021 Page: 1749 Information© 2022 The American Phytopathological SocietyFundingNational Polytechnic Institute (Instituto Politécnico Nacional)Grant/Award Number: SIP20201117Keywordsfungifruitsmall fruitspathogen detectionThe author(s) declare no conflict of interest.PDF downloadCited ByPodosphaera xanthii causing powdery mildew on Impatiens balsamina in China16 December 2021 | Canadian Journal of Plant Pathology, Vol. 44, No. 3