Microbial Diversity in the Phyllosphere and Rhizosphere of Field Grown Crop Plants: Microbial Specialisation at the Plant Surface

摘要

The phyllosphere is broadly defined as the surfaces and internal parts of the aerial structures of plants, including flowers, fruits, stems and leaves. Specialised microbial colonists, phytopathogens, spoilage organisms and periodic immigrants have all been described as residents of this physically diverse habitat. As plants represent one of the most important features of our landscape and our primary food source it is somewhat surprising that only a limited number of detailed investigations have been conducted that describe this above-ground microbiology. This is in contrast to the attention that soil rhizosphere systems receive. Pertinent investigations reveal a diverse and specialised microbial community that is distinct from the rhizosphere. Bacteria are by far the most numerically abundant colonisers; typical community densities up to of 2 chi10~7 cells per cm~2 of leaf surface have been recorded by traditional methods (Andrews and Harris, 2000). Although given the varied nature of the environment that aerial portions of plants provide numbers can vary from 10s to in excess of 1 chi 10~(12) in arid and senescing leaves respectively.