The Effects Of Numerically Dominant Endophyte Colletotrichum Spp. Of Ageratina Adenophorum On Economic Crops

With the develepement of human activities and the acceleration of the globalization, bio-invasion has been becoming more and more serious, and produced severe threatens to the ecosystem in China. Among of them, invasive plants have brought huge losses to China’s agriculture and forestry. However, previous studies has mainly focused on the damages caused by invasive plants themselves.In recent years, many studies have shown that invasive plants can accumulate pathogens of local plants. However, the effects of these pathogens on local plants have not yet been studied sufficiently. Based on "Accumulation of local pathogens hypothesis "and "New weapons hypothesis", this study tries to explore the effects of endophytic Colletotrichum spp. in leaves of an invasive plant Ageratina adenophorum on local economic crops.We used spore suspension of eight strains of Colletotrichum spp. to infect fruits of four crops, including Lycopersicon esculentume, Mangifera indica, Musa Nona, and Citrus junos; seeds of Lycopersicon esculentum, Cucumis sativus, Zea mays, Alnus nepalensis. Meanwhile, the effects of these strains on the survival of L. esculentume seedlings were also tested.In addition, a field experiment was performed to detect the pathogenic effects of these strains on the leaves of two kinds of economic forests including Alnus nepalensis and Rubus corchorifolius. The following conclusions were obtained:1. Some endophytic Colletotrichum spp. strains of A. adenophorum are pathogenic on the fruits of crops.Among of eight Colletotrichum spp. strains, there are 3 strains pathogenic on M. indica fruits,4 strains on C.junos fruits; 6 strains on L. esculentume fruits, and 6 strains on M. Nana fruits.2. Endophytic Colletotrichum spp. strains of A. adenophorum have great negative effects on seed germination and seedling growth of crops.Eight Colletotrichum spp. strains have inhibitory effects on seed germination of four kinds of crop, although the effects on seed germination rate and time are not statistically significant. However, these strains showed high mortality on seedlings of crops, and most seedling survival rates varied from 10% to 20%.3. Some endophytic Colletotrichum spp. strains of A. denophorum have seriously adverse effects on the growth of I. esculentum.Inoculating strain AX115 caused L. esculentum leaves withered and become yellow, and leaf color is deeper than the control group. Meanwhile, AX115 had also significant negative effects on the ground and underground biomass, with a decrease of 41% and 22%, respectively, when comparing with the control group.In addition, AX115 and JK121 strains had significant inhibitory effects on stem length of plant, and reduced 45% and 28%, respectively.4. Endophyte Colletotrichum spp. strains of A. adenophorum have pathogens on local economic trees.Experimental strains can inhibit seed germination of A. nepalensis, and cause seedling death. Meanwhile, many strains also cause leaf disease of A. nepalensis and R. corchorifolius field experiments.Overall results showed that endophytic Colletotrichum spp. strains of A. adenophorum have pathogenicity on fruits, germination timing, germination rate, seedling growth and leaf of crops. These endophytes may increase the possibility of disease outbreaks of crops and economic forests in the areas invaded by A. adenophorum.