Symbiotic and endophytic fungi as biocontrols against cocoa (Theobroma cacao L.) phytopathogens

Abstract

Cocoa (Theobroma cacao L.) is a tropical tree, seriously affected by fungal diseases. To control several pathogens, biological methods are prescribed since they are friendly to the environment and easy to use. The main objective of this study was to assess the biocontrol effect of two native strains, Trichoderma viride and Botryosphaeria quercum, on phytopathogens such as Phytophthora palmivora and Moniliophtora roreri, causal agents of black pod and frosty pod rot diseases, respectively. In addition, biocontrolers were faced on potential mycotoxigenic fungi such as Aspergills flavus and Fusarium solani, which are very common on cocoa. The Bio-Control Index (BCI) was calculated to determine the in vitro biocontrol effect against the biocontrole contra quatro fitopatógenos. Os resultados indicaram que o melhor agente de controle biológico de fitopatogenos era B. quercum, que mostra 82,3% de BCI e 80,7%, 63,3% e 59,7% para cad a um dos fitopatógenos testados, respectivamente. A competição por substrato foi a estratégia utilizada no controle biológico. As estirpes, provenientes do Departamento de Santander e Santander Norte apresentaram a maior inibição percentual média. Este estudo é um inicial para sobre o poten c ial endófito e antagonística de fungos, capazes de colonizar as especificamente bagas de cacau e solo. Assim, estas estirpes podem ser indicadas uma alternativa eficiente contra fitopatógenos de cacau importantes. Palavras-chave: Cacau, patógenos,cogumelos, biocontroleCocoa (Theobroma cacao L.) is a tropical American tree flowering all year long and bearing a fruit known as pod. Colombia is the ninth producer in the world and the third one in Latin America, after Brazil and Ecuador. Estimated projections indicate that by 2021 Colombia might produce 285,600 Mg cocoa, as cocoa tree plantations are expected to reach over 230,000 ha (11); however, 50% to 90% cocoa production is affected by fungal diseases (2,4). The most prevailing infections are frosty pod rot (caused by the fungus Moniliophthora roreri) and black pod (the etiological agent of which is Phytophthora sp.), both causing cocoa crop losses of up to 100% (15). In addition, there are secondary infections caused by phytopathogens like Aspergillus and Fusarium that attack opportunistically as cocoa deteriorates, thus accelerating pod degradation and leaving traces of mycotoxins (3).To reduce the effects of fungal phytopathogens, cocoa growers apply good cropping practices, sometimes combined with the use of fungicides. The first method is easy to apply but labor demanding and is only economically viable if the cocoa price in the market is high (8). In the case of fungicides, they certainly protect the plant

Diversity of Endophytic Fungi of Psidium guajava (Myrtaceae) and Their Antagonistic Activity against Two Banana Pathogens

“…cubense. Furthermore, in a similar study conducted by Villamizar-Gallardo et al [85], the results showed that the growth of Phytophtora palmivora and Moniliophora roreri, two cocoa pathogens, was respectively inhibited by 82.3 and 80.7% by an endophytic fungus of the genus Botryosphaeria (B. quercum). Likewise, the antagonistic activity of the endophyte Xylaria sp.…”

“…Endophytic fungi are studied for their multiple antimicrobial properties, including their antifungal activity. This has been demonstrated in several studies [83][84][85][86][87][88]. The in vitro screening of this antifungal activity is largely carried out by the double culture method (direct confrontation test).…”

Regional Evaluation of Fungal Pathogen Incidence in Colombian Cocoa Crops

“…Diseased pods exhibited typical symptoms of each of the above-mentioned diseases. The collected pods were packed in plastic, labeled, and transported in boxes to the laboratory of Nanosost (Nanotechnology and Sustainable Research Group at the Universidad de Pamplona, Pamplona, Colombia) for later analysis [6].…”

“…Phytopathogens were obtained from cocoa pods exhibiting the symptoms of each disease. Spores present in the upper and inner pod cortex were directly cultured on petri dishes containing potato dextrose agar modified with cocoa pod cortex extract and chloramphenicol (CEC-PDA) [6]. Isolated colony forming unit were re-cultured until obtaining axenic colonies, which were subsequently characterized.…”

“…Phytopathogenic diseases cause 30 to 100% annual losses of the cocoa harvest [6]. Frosty pod rot (FPR), caused by the endemic fungus Moniliophthora roreri (Cif.…”