Diversity and distribution of fungal endophytes associated with native Syzygium cordatum in South Africa

Abstract

Endophytes are organisms that inhabit plant organs and colonise plant tissues without causing obvious signs of disease. Much research has been done to elucidate the effects that endophytes have on their hosts, but the majority of these studies have been done on grass species that are considered model organisms. Evidence shows that endophytes evolved from closely related pathogenic fungi, because many endophytes are latent pathogens or saprobes that only sporulate when their hosts are stressed or dying. Hence, it is important to understand the principles surrounding endophyte biology and the effects that they could have on their hosts. There are specialised mechanisms involved enabling endophyte-host interactions to exist and these have co-evolved over millions of years. Endophytic symbionts affect the growth and fitness of their hosts, as well as their ability to tolerate biotic and abiotic stressors. In most cases, however, the ecological role and basis for the interaction between plants and their diverse assemblage of endophytes remain obscure and this is especially true for trees. Given the prominent presence of endophytes and the large part of biological diversity that they represent, further work to clarify these roles is urgently needed. This review aims to establish an understanding of the theory surrounding fungal endophytes, endophyte-host interactions, modes of infection, the influence of endophytes on their hosts, the co-evolution of life-history traits and why endophytes are important in their environments.