Evaluating the feasibility of induced host resistance by endophytic isolate Penicillium citrinum BTF08 as a control mechanism for Fusarium wilt in banana plantlets

Penicillium citrinum BTF08 was evaluated for its biocontrol potential against the pathogenic Fusarium oxysporum f. sp. cubense race 4 (FocR4) in banana plantlets via induction of host resistance. Disease assessments were recorded weekly and their biochemical markers (peroxidase, polyphenoloxidase, phenylalanine ammonia lyase) assayed. Results showed colonization of P. citrinum BTF08 resulted in significant levels of PO and PPO that were detected in plantlets pre-treated with P. citrinum BTF08. These levels of 98.35 units g−1 tissues and 57.25 units g−1 tissues were higher compared to levels assayed from plantlets infected with only pathogenic FocR4 with 63.7 units g−1 tissues and 45.80 units g−1 tissues, for PO and PPO, respectively. The elevated levels of PO and PPO suggest the occurrence of induced host resistance in P. citrinum BTF08-treated plantlets, and this benefited the plantlets, as they recorded lower percentages of disease incidence and severity, and delayed symptom progression. However, at the end of 28 days, all plantlets succumbed to Fusarium wilt with 80% disease incidence and 42% disease severity. Our study is the first to document the induction of host resistance by P. citrinum BTF08 and their efficacy to suppress wilt incidence.