It is estimated that the terrestrial leaf surface area that might be colonized by microbes is about 6.4 × 10 8 km 2 ( 83). Leaves constitute a very large microbial habitat. This is somewhat surprising given the abundance of plants in the world and the roles of various phyllosphere bacteria in the important processes discussed below. Because of their numerical dominance on leaves, and because more information is available on the process of bacterial colonization of leaves, we focus on this group of microbes in this review.Ĭompared to most other bacterial habitats, there has been relatively little examination of phyllosphere microbiology. Bacteria are by far the most numerous colonists of leaves, often being found in numbers averaging 10 6 to 10 7 cells/cm 2 (up to 10 8 cells/g) of leaf ( 1, 7, 41). While there has been some investigation of the colonists of buds and flowers ( 1, 48), most work on phyllosphere microbiology has focused on leaves, a more dominant aerial plant structure. The aerial habitat colonized by these microbes is termed the phyllosphere, and the inhabitants are called epiphytes. While a few microbial species can be isolated from within plant tissues, many more are recovered from the surfaces of healthy plants. The above-ground parts of plants are normally colonized by a variety of bacteria, yeasts, and fungi.

Flower that starts with phlo