Dissertation Research: Tropical Fungal Endophyte Diversity and Ecology

9902346McDade热带真菌内生菌代表了一种探索共生菌作为植物抗病媒介的新系统。这项研究将调查热带真菌内生菌的多样性及其在森林植物-病原菌系统中的相互作用。真菌内生真菌是生活在空中植物组织中的各种无症状的子囊菌，在热带树木的叶子中非常丰富。鉴于内生菌是异养菌，可能会给宿主带来成本，而且热带树木对各种真菌有很好的化学保护，为什么热带树木拥有如此丰富的真菌内生菌？本论文的研究将验证内生菌通过提高寄主植物对真菌病原菌的抗性而起到互惠互利的作用的假设。在巴拿马的巴罗科罗拉多岛，一种常见的树冠树--瘤毛藻(Meliaceae)上的内生植物群落将被量化，并与其他宿主树种进行比较。体外试验将评估内生菌对引起结核杆菌菌核病的未描述的子囊菌生长和存活的影响，而体内生长室内实验将评估在存在和不存在病原体的情况下内生菌感染的成本和收益。这项研究将加深我们对寄主-共生菌-病原菌相互作用和真菌生物多样性的理解。

9902346McDadeTropical fungal endophytes represent a novel system for exploring symbionts as mediators of plant resistance to pathogens. This study will investigate the previously undescribed diversity of tropical fungal endophytes and their interactions in a forest plant-pathogen system. Fungal endophytes, the diverse, asymptomatic Ascomycetes that inhabit aerial plant tissues, are remarkably rich in the leaves of tropical trees. Given that endophytes are heterotrophs and likely exert a cost upon the host, and that tropical trees are well-defended chemically against a diversity of fungi, why do tropical trees harbor such a richness of fungal endophytes? This dissertation research will test the hypothesis that endophytes act as mutualists by enhancing host plant resistance to fungal pathogens. At Barro Colorado Island, Panama, endophyte communities on Trichilia tuberculata (Meliaceae), a common canopy tree will be quantified and compared to other host tree species. In vitro assays will assess the influence of endophytes on the growth and survival of the undescribed Ascomycete that causes shot-hole disease in T. tuberculata, while in vivo growth chamber experiments will assess the costs and benefits of endophyte infection in the presence and absence of the pathogen. This study will enhance our understanding of both host-symbiont-pathogen interactions and fungal biodiversity.