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 four phytopathogens. Results indicated that the best biocontrol agent of phytopathogens was B. quercum, showing BCI of 82.3%, 80.7%, 63.3% and 59.7% for each tested phytopathogen, respectively. Competition for substrate was the dominant biocontrol strategy. As to the origin of strains, those coming from the Department Norte de Santander and Santander showed the highest average inhibition percentage. This study provides an initial screening to the endophytic and antagonistic potential of fungi, specifically those capable of colonizing cocoa pods and soils. Thus, these strains can be used as an efficient biological control alternative against several known phytopathogens of cocoa in the field.

摘要 可可（Theobroma cacao L.）是一种热带乔木，其生长严重受真菌病害侵扰。为防控多种病原菌，生物防治方法因环境友好且操作简便而被广泛推荐用于病害治理。本研究的核心目标为评估两株本地菌株——绿色木霉（Trichoderma viride）与栎葡萄座腔菌（Botryosphaeria quercum）——对两种关键植物病原菌的生防效果：即引发可可黑荚果病的棕榈疫霉（Phytophthora palmivora），以及引发可可霜荚果腐病的可可荚果霜腐病菌（Moniliophthora roreri）。此外，本研究还针对可可种植中常见的产毒真菌黄曲霉（Aspergillus flavus，原文笔误为Aspergills）与茄腐镰孢菌（Fusarium solani），测试了这两株生防菌的拮抗活性。通过计算生物防治指数（Bio-Control Index, BCI），以测定其对四种供试植物病原菌的离体生防效果。试验结果表明，栎葡萄座腔菌对供试病原菌的生防效果最优，其针对四种供试病原菌的BCI分别为82.3%、80.7%、63.3%与59.7%。底物竞争是该类生防菌的主导生防策略。就菌株来源而言，分离自北桑坦德省与桑坦德省的菌株展现出最高的平均抑菌率。本研究针对真菌的内生性与拮抗潜力开展了初步筛选，尤其聚焦于可定殖可可荚果与土壤的菌株。综上，这些菌株可作为田间可可多种已知植物病原菌的高效生物防治替代方案。