Desvendando a etiologia do complexo de doenças “Podridão de Phomopsis” da berinjela no Brasil e busca por fontes de resistência de amplo espectro em Germoplasma de Solanum melongena L.

Abstract

Eggplant (Solanum melongena L.) is the fourth economically important vegetable in the Solanaceae family. Despite being a very rustic crop, which is more tolerant to diseases than other species in the Solanaceae family, such as tomatoes, potatoes and peppers, many problems still interfere with its productivity, mainly the phytosanitary nature. Phomopsis rot is one of the main diseases of eggplant present in the main producing centers in Brazil. The disease affects the entire aerial part of the plant, however the greatest damage occurs when the pathogen affects the leaves and fruits. Infected fruits develop initially long-lasting rot, which can progress to soft rot and tissue interference. Injuries to the stem can lead to wilting and death of the branches above them. Dark brown, circular and concentric spots form on the leaves, which can be confused with those caused by Alternaria spp. To control the disease, the use of healthy seeds and seedlings, agricultural pesticides and the use of resistant cultivars are recommended. In the latter, the hybrid ‘Ciça’ (released as resistant to the fungus D. vexans) and other cultivars have been shown to be susceptible to pathogens under field conditions. Therefore, the present work aimed to clarify the etiology of Phomopsis rot in Brazil, in addition to testing the pathogenicity of isolates in fruits (cv. Ciça) and evaluating the collection of eggplant accessions belonging to Embrapa Hortaliças, discovering sources of effective genetic resistance against the possible causal agents of the disease. The phylogenetic analyzes carried out based on sequence information from genomic regions (ITS- internal transcribed space, TEF- elongation factor, Tub-2- beta tubulin and ACT- α actin) for 21 isolates, identified a complex of fungal species causing illness. Recognized as: (Boeremia sp1 and Boeremia sp2), Cumuliphoma pneumoniae, (Diaporthe endophytica, D. griceae and D. vexans) and (Stagonosporopsis sp. and S. pogostemon). This is the first report of the species occurring in eggplant in Brazil. The pathogenicity test on fruits (cv. Ciça) was carried out by inserting mycelium discs using the methods with (CF) and without injury (SF) into fruits, for 4 isolates. During the evaluation, the diameter of the lesions on each fruit was measured, and the area under the disease progress curve (AACPD) was calculated. No pathogenic variability was identified for the isolates, despite this, wound assays (CF) demonstrated higher AACPD values. In the selection of resistance sources, of the 61 accessions tested, for two of the pathogen isolates, disease severity data were used to calculate the area under the disease progress curve (AACPD). Thus, 67.22% of accessions are resistant to Boeremia sp. and 83.60% were resistant to D. griceae.