Pathogenic Strategies of Fungi

Abstract

Fungi are the most important group of pathogens on plants from an economic point of view. This results in part from the fact that fungi are extremely varied in the ways they attack plants and actively move through host tissues, forcibly breaching barriers by enzymatic and/or physical mechanisms. In addition, fungal pathogens exhibit a complex array of tropic responses which may contribute to complex infection processes and are important in determining host range. Fungal interactions with plants are based on parasitism, a nutritional relationship, but the economic and aesthetic damage which they cause may result from the operation of other factors that constitute pathogenicity. While these two terms are frequently used interchangeably, they are distinct; indeed, it is possible to have pathogenesis without parasitism and vice versa. Although fungal diseases have been studied for over a century, we are only beginning to understand the molecular factors which determine whether a certain fungus is pathogenic on a higher plant. In this paper, I will review some of the progress that has been made, point out deficiencies in our knowledge and speculate on the future, especially on ways in which the powerful machinery of molecular genetics is being brought to bear on fungal pathogens. Because of the survey nature of the paper, references are exemplary only.