Disease risk of the foliar endophyte Colletotrichum from invasive Ageratina adenophora to native plants and crops

The disease risk driven by foliar fungi asymptomatically infecting invasive plants has rarely been determined. In this study, we selected 44 foliar Colletotrichum endophytes isolated from the invasive plant Ageratina adenophora that are phylogenetically closely related to the C. gloeosporioides complex, C. boninense complex, C. orchidearum complex, and C. acutatum complex and evaluated their potential virulence and ability to transmit spores to native plants and cash crops both in vitro and in vivo. We verified that some foliar endophyte Colletotrichum strains adversely affect the leaf and seed germination of native plants and cash crops. Some strains reduce the growth and yield of tomato (SL) (Solanum lycopersicum) and pepper (CA) (Capsicum annuum) plants and even cause the death of strawberry (FA) plants (Fragaria ananassa). Moreover, we confirmed that A. adenophora leaves could horizontally transmit Colletotrichum to surrounding crop plants in vivo. Therefore, a high abundance of Colletotrichum asymptomatically associated with A. adenophora leaves might increase disease risk in surrounding native plants and cash crops. Our results provide a new perspective for regional ecological risk assessment of invasive plants and prevention of economic plant diseases in the invaded range.