Phytophthora theobromicola sp. nov.: A New Species Causing Black Pod Disease on Cacao in Brazil

Autor: Ailton Reis, Edna Dora Martins Newman Luz, Jennifer Decloquement, Danilo Batista Pinho, Dahyana Santos Britto, Samuel Galváo Elias, Jean-Philippe Marelli, Rildo Alexandre Fernandes da Silva, Jaime Honorato-Júnior, Alina S. Puig, Roberto Ramos-Sobrinho
Přispěvatelé: JENNIFER DECLOQUEMENT, UNIVERSIDADE DE BRASÍLIA, ROBERTO RAMOS-SOBRINHO, Biophyto Plant Health LTDA, SAMUEL GALVÃO ELIAS, UNIVERSIDADE DE BRASÍLIA, DAHYANA SANTOS BRITTO, Mars Center for Cocoa Science, ALINA SANDRA PUIG, USDA-ARS/Subtropical Horticultural Research Station., AILTON REIS, CNPH, RILDO ALEXANDRE FERNANDES DA SILVA, UNIVERSIDADE DE BRASÍLIA, JAIME HONORATO-JÚNIOR, UNIVERSIDADE FEDERAL DO OESTE DA BAHIA, EDNA DORA MARTINS NEWMAN LUZ, Centro de Pesquisas do Cacau, Comissão Executiva do Plano da Lavoura Cacaueira, DANILO BATISTA PINHO, UNIVERSIDADE DE BRASÍLIA, JEAN-PHILIPPE MARELLI, Mars Plant Sciences Laboratory, Davis.
Rok vydání: 2021
Předmět:
Zdroj: Frontiers in Microbiology, Vol 12 (2021)
Repositório Institucional da EMBRAPA (Repository Open Access to Scientific Information from EMBRAPA-Alice)
Empresa Brasileira de Pesquisa Agropecuária (Embrapa)
instacron:EMBRAPA
Frontiers in Microbiology
ISSN: 1664-302X
Popis: Black pod disease, caused by Phytophthora species, is among the main limiting factors of cacao (Theobroma cacao L.) production. High incidence levels of black pod disease have been reported in Brazil, being induced by Phytophthora capsici, Phytophthora citrophthora, Phytophthora heveae, and Phytophthora palmivora. To assess the diversity of Phytophthora species affecting cacao in Brazil, 40 new isolates were obtained from cacao pods exhibiting symptoms of black pod disease collected in different smallholder farms in 2017. Further, ten cacao-infecting isolates morphologically identified as P. citrophthora and P. palmivora were molecularly characterized. The genomic regions beta-tubulin, elongation factor 1 alpha, heat shock protein 90, and internal transcribed spacer, and the mitochondrially encoded cytochrome c oxidase I and II genes were PCR-amplified and Sanger-sequenced from the cacao-infecting Phytophthora isolates. The morphological characterization and evaluation of the mycelial growth rates for the Phytophthora isolates were performed in vitro. Based on the molecular analysis and morphological comparisons, 19 isolates were identified as P. palmivora (clade 4). Interestingly, 31 isolates grouped together in the phylogenetic tree and were placed apart from previously known species in Phytophthora clade 2. Therefore, these isolates are considered as a new species herein referred to as Phytophthora theobromicola sp. nov., which produced papillate, semipapillate, and persistent sporangia on simple sporangiophores. The P. palmivora isolates were identified as A1 mating type by pairing each isolate with known A1 and A2 tester strains of P. capsici, but no oogonia/antheridia were observed when P. theobromicola was paired with the different tester strains. The P. theobromicola and P. citrophthora isolates showed higher mycelial growth rates, when compared to P. palmivora, on different media at 10, 15, and 20°C, but similar values were observed when grown on clarified CA media at 25 and 30°C. The pathogenicity tests carried out on pods of four cacao clones (CCN51, PS1319, Cepec2004, and CP49) showed significant variability among the isolates of both Phytophthora species, with P. theobromicola inducing higher rates of necrotic lesion expansion, when compared to P. palmivora. Here, two Phytophthora species were found associated with black pod disease in the state of Bahia, Brazil, and the previously undescribed P. theobromicola seems to be prevalent in field conditions. This is the first report of P. theobromicola on T. cacao. Also, these findings are crucial to improve the disease control strategies, and for the development of cacao materials genetically resistant to Phytophthora.
Databáze: OpenAIRE
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