Trichoderma Culture Filtrates: Promising Biocontrol Agents for Potato Virus Y Management

Abstract The potato crop ranks as the fourth most important food crop after rice, wheat and maize. Approximately 50 viruses affect potato plants, with potato virus Y (PVY) being the most serious one. To date, an effective anti-PVY agent remains elusive. The current study investigates the potential of Trichoderma culture filtrates as antiviral agents against PVY. PVY and Trichoderma isolates were molecularly identified using the PCR technique and sequence analysis. To evaluate the effectiveness of Trichoderma culture filtrates (TCFs) in controlling PVY, the gene expression of the PVY-CP gene and the PR1-b gene was assessed using RT-qPCR. In addition, evaluations of defence-related enzymes and vegetative parameters of potato plants were conducted. Molecular identification revealed that the virus isolate is closely related to PVY species and was deposited in the GenBank database as PVY isolate EGY-RIZK24 (PP375808). Based on the sequence of the tef1 gene, Trichoderma isolates were identified as follows: T1 as T. asperellum isolate Ketta (PP228382), T2 as T. asperellum isolate RIZK24T2 (PP228383), and T4 as T. asperelloides isolate RIZK24T4 (PP228384). Foliar spraying of TCFs significantly reduced the PVY load in the treated potato plants compared to the PVY-infected control. The reductions were 89.8% for TCF1, 86.1% for TCF2, 79.2% for TCF3, and 68.5% for TCF4. The expression of PR1-b significantly increased in TCF1, TCF2, and TCF3 treatments (2.38, 2.16, and 1.35, respectively) compared to untreated plants. TCF-treated plants also exhibited a significant increase in superoxide dismutase (SOD) content compared to untreated controls. The effect of TCF treatments on peroxidase and polyphenol oxidase activity varied. Overall, plants treated with TCFs exhibited a notable increase in chlorophyll content compared to the PVY-infected control. Interestingly, a negative correlation was found between PR1-b , SOD, chlorophyll content variables, and PVY levels. The results demonstrate a beneficial effect of TCFs, particularly TCF1 and TCF2, in reducing virus content and enhancing PR1-b gene levels, antioxidant enzymes, and chlorophyll content. These TCFs demonstrate dual functionality as effective anti-PVY agents and as inducers of systemic resistance to PVY infection. This discovery paves the way for developing an innovative and sustainable product for controlling PVY, highlighting the need for further investigations in future research. Graphical Abstract