Study on the functions of the autophagy related gene ChAtg3 in Colletotrichum higginsianum

Objective To study the role of ChAtg3, an autophagy-related gene in Colletotrichum higginsianum.

Method The sequence, phylogeny and expression pattern of ChAtg3 were analyzed, and the expression changes of ChAtg3 were observed in Arabidopsis thaliana after infection with C. higginsianum. An Agrobacterium tumefaciens-mediated genetic transformation system was employed to perform specific gene knockouts and their subsequent complementation.

Result The expression changes of ChAtg3 were observed after C. higginsianum infected A. thaliana for 8 to 40 h. The mutant ΔChAtg3, created through targeted ChAtg3 gene knockout, exhibited impaired autophagy, with markedly reduced melanin production, conidiation, appressorium formation, and pathogenic potential, although mycelial growth and conidial germination rate had no significant changes compared with wild type. Gene complementation in the CΔChAtg3 strain effectively reinstated its biological phenotype and pathogenicity.

Conclusion The results reveal that ChAtg3 plays a key role in autophagy, conidiation, and appressorium formation of C. higginsianum, confirming it as a critical determinant of pathogenic capacity of C. higginsianum.