The Phyllosphere

Rhizosphere and the Phyllosphere
Rhizosphere Introduction
Rhizospher Effect
Nitrogen Fixation in the Rhizosphere
Alteration of Rhizosphere Microflora
Associative and Antagonistic Activities in the Rhizosphere
Root Exudates
Organic Compounds Detected in Plant Root Exudates
Fungistasis
Techniques of Rhizosphere
The Soil Dilution and Plate Count Method
The Soil Plate
The Soil Box
The Contact Slide Technique
Artificial Rhizosphere
Model System

The Phyllosphere

	The Phyllosphere Plant parts, especially leaves are exposed to dust and air currents resulting in the establishment of a typical flora on their surface aided by the cuticle, waxes and appendages which help in the anchorage of microorganisms. These microorganisms may die, survive or proliferate on leaves depending on the extent of influence of the materials in leaf diffusates or exudates. Leaf diffusates or leachates have been analysed for their chemical constituents. The principal nutritive factors are amino acids, glucose, fructose and sucrose.
If the catchment areas on leaves or leaf sheaths are significantly substantial, such specialized habitats may provide niches for nitrogen fixation and secretion of substances capable of promoting the growth of plants. The leaf surface has been termed 'phylloplane' and the zone on leaves inhabited by microorganisms as 'phyllosphere'. The Dutch microbiologist Ruinen coined the word 'Phyllosphere' from her observations on Indonesian forest vegetation where thick microbial epiphytic associations exist on leaves. The dominant and useful microorganisms on the leaf surfaces in the forest vegetation in Indonesia happened to be nitrogen-fixing bacteria such as Beijerinckia and Azotobacter.
In general, apart from nitrogen-fixing bacteria like Azotobacter, other genera such as Pseudomonas, Pseudo bacterium, Phytomonas, Erwinia, Sarcina and other unidentified ones have been encountered on plant surface, especially on leaf surface. In Puerto Rico, nitrogen-fixing blue-green algae such as Anabaena, Calothrix, Nostoc, Scytonema and Tolypothrix have been encountered on plant surfaces in moss forests.
Some of the fungi and actinomycetes recorded on the plant surface are: Cladosporium, Alternaria, Cercospora, Helminthosporium, Erysiphe, Sphaerotheca, Podospora, Uncinula, Sporobolomyces, Bullera, Cryptococcus, Rhodotorula, Torula, Torulopsis, Oidium, Puccinia, Melanospora, Saccharomyces, Candida, Tilletia, Tilletiopsis, Penicillium, Cephalosporium, Fusarium, Periconia, Darluca, Rhynchosporium, Spermospora, Aureobasidium, Colletotrichum,. Metarrhizium, Myrothecium, Verticillium, Pithomyces (potential skin infecting genus), Mucor, Cunninghamella, Fusarium, Aspergillus, Curvularia, Rhizopus, Trichoderma, Heterosporium, Stachybotrys, Syncephalastrum, Actinomyces and Streptomyces.

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