Invasion Of Eupatorium (eupatorium Adenophorum Spreng,) Leaf Endophytic Fungi Diversity

In current research work about invasive plants has been one of the most hot topics of ecology and environmental science. The key question for the invasive mechanisms is why the invasive plant generally displays greater growth competetion over the native plants in the introduced range. However, no hypothesis could alone explain well about this question, because successful invasion of a plant species may result from a complicated process, which involves biological characteristics and adaptation to new habitat of exotic species, as well as its competetion with native plant species. In very recent year, several research reports prove that invasiveness of exotic plants greatly are contributed by their leaf fungal endophytes. However, most works have focused on grasses, little has been known about endophytes in plant other than grass.In this case, fungal endophytes were isolated and species composition were determined from 19 populations of Eupatorium adenophorum (Asteraceae), a notorious invasive plants in southwest of China. Some conclusions were made:1. Fungal endophyte diversity increased from 1st pair of leaves (young leaves) to 4th pair of leaves (old leaves), with lightly decrease in the 6th pair of leaves (the oldest leaves);2. In the winter the population lived in shadowed habit displayed the highest number of fungal endophytes, however, those lived in empty environments displayed the lowest number of fungal endophytes;3. Endophytes grow differently among media containing extracts from 6 pairs of leaves. Growth rates of Alternaria were inhibited significantly by the leaf extracts but no difference was found between different leaves. In contract, growth of Didymella on media contained leaf extracts exceeded that on media without leaf extracts. Relatively old-aged leaf was more favorable to the growth of Didymella;4. Most interactions between endophytes strains through non-volatiles and volatiles were neutral or negative;5. Both the occurrence frequency and diversity of fungal endophytes are negatively correlated with altitude and latitude, but positively correlated with invasive history of E. adenophorum;6. In total 840 endophytes were isolated from E. adenophorum populations across Yunnan province and southern Shicuan province. Based on the RFLP patterns and DNA sequences of their ITS rRNA gene, these strains were divided into 34 genera. Dominant groups include Collectotrichum, Alternaria, Xylaria and Diaporthe.In conclusion, E. adenophorum contained a variety of fungal endophytes in leaves. The species diversity increased with its invasive history.