The Effects Of Foliar Endophytes On The Growth Of Ageratina Adenophora And Native Plants

Since 1940s, Ageratina adenophora has invaded into the Southwest China including Yunnan, Guizhou, Sichuan, Guangxi, and Tibet province, etc., from the Sino-Burmese border, and caused huge damage to these areas economically and ecologically. However, the invasion mechanism about A. adenophora has not yet been fully understood. In order to explore the role of foliar endophytes in the invasion of A. adenophora, we discussed the relationships among foliar endophytes, A. adenophora and local plants, based on the hypothesis "Accumulation of local pathogens". This study tries to explain a possible mechanism about the invasion of A. adenophora through the help of endophytes.Based on the green house experiment, we tested the effect of foliar endophyte community and dominant fungal species involving Fusarium, Colletotrichum, Alternaria and Nemania of A. adenophora on germination rate, germination timing, the biomass of A. adenophora itself and five native plants including Arthraxon lanceolatus, Amaranthus caudatus, Achyranthes aspera, Fallopia multiflora and Abelmoschus moschatus. Main conclusions we drew are as following:1. Foliar endophytes of A. adenophora are beneficial for its host’s growthCompared to native plants, foliar endophyte community of A. adenophora did a greater facilitation in the growth of its roots and stems. When A. adenophora was cultured alone, supplement of either 0.05g or 0.1 g leaves of A. adenophora into the culture medium showed a positive influence on the growth of roots. Meanwhile, no matter A. adenophora was cultured alone and cultured with native plants, and whatever the leaves we added was 0.05g or 0.1g, foliar endophyte community of A. adenophora had the positive effect on the growth of stems. In addition, if foliar endophytes are beneficial for both native and invasive plants, relatively, endophytes showed bigger stimulation to invasive plant A. adenophora than to natives. For example, when we added 0.05g leaves of A. adenophora, the growth of native plant F. multiflora was increased by 22.93%, while the growth of A. adenophora was increased by 68.79%. However, endophytes community played no role in both germination timing and germination rate.2. The effect of foliar endophytes of A. adenophora on native plants are cultivation condition-dependendWhen adding 0.05g leaves of A. adenophora, the germination rate of three native species (60%) was inhibited if these native plants were cultivated alone but only one species (20%) was inhibited if these natives were cultivated with invasive plant A. adenophora. When adding 0.1g leaves of A. adenophora, the germination rate of two native species (40%) was inhibited if these native plants were cultivated alone but only one species (20%) was inhibited if these natives were cultivated with invasive plant A. adenophora. Meanwhile, we tested the influence adding different amount of leaves on roots and stems, together with the change from culturing the native plants alone to culturing both the native plant and A. adenophora. When added 0.05g leaves, the inhibiting effect of foliar endophytes on roots of native plants increased from one species (20%) to two species (40%); the inhibiting effect of foliar endophytes on stems of native plants increased from one species (20%) to three species (60%). When added 0.1g leaves of A. adenophora, no effect was detected on the growth of roots of native plants, but the inhibiting effect of foliar endophytes on stems of native plants increased from 0 species to two species (40%). This results suggested that endophytes had different influence on native plants with the change of cultivation condition.3. Dominant foliar endophytes in A. adenophora had different influences on the performance of four native plants and invasive plants, adenophoraAmong the four dominant fungal endophytes, Alternaria XS30 showed great inhibiting effect on roots of A. adenophora, while showing facilitation in germination rate, germination timing and underground part (fresh weight). Colletotrichum JK108 showed facilitation in germination timing, stems, roots, aboveground part (fresh weight), underground part (fresh weight) and the number of leaves. F. graminearum XS186 showed facilitation in stems and the number of leaves. Nemania AX79 showed facilitation in germination timing, stems, roots, aboveground part (fresh weight), underground part (fresh weight) and the number of leaves. Meanwhile, four dominant endophytes did not have significant lethal effect on A. adenophora. However, four dominant endophytes showed great inhibiting effect on the growth of Achyranthes aspera. Colletotrichum JK108 and F. graminearum XS186 showed great inhibiting effect on the growth of Arthraxon lanceolatus. F. graminearum XS186 and Alternaria XS30 showed great inhibiting effect on the growth of Amaranthus caudatus. F. graminearum XS186 showed great inhibiting effect on the growth of F. multiflora. Colletotrichum JK108 showed great inhibiting effect on stems of F. multiflora.Alternaria XS30 and Nemania AX79 showed great inhibiting effect on roots of F. multiflora. Four dominant endophytes showed little influence on the germination timing and germination rate of four native plants.In conclusion, foliar endophytes of A. adenophora on one side are able to stimulate the growth performance of A. adenophora itself, but on the other side adversely affect the growth performance of native plants we detected in this study. Therefore, we suggested that foliar endophytes of A. adenophora could be a weapon faciliating the invasion of A. adenophora.