GENERAL MICROBIOLOGY - T.P. Pyrog - 2004

8. FUNGI

8.7. BIOLOGICALLY ACTIVE SUBSTANCES OF FUNGI

8.7.5. Plant Growth Stimulants and Vitamins

Growth stimulants (regulators) are substances that promote plant growth in very small quantities. They include Auxins and Gibberellins.

Auxins were discovered in the 1930s. Chemically, they belong to the group of β-indolylacetic acid compounds. Auxins are produced by numerous soil saprophytic Bacteria, actinomycetes, and Fungi.

Gibberellins are synthesized by the fungi Fusarium moniliforme and Fusarium oxysporum. They were first discovered in Japan in 1935 while studying a rice plant disease. Today, several dozen gibberellins are known. Chemically, they are acyclic compounds of the fluorene series. Treatment with gibberellins allows winter crops to bear fruit without undergoing the vernalization stage (exposure to low temperatures); biennial plants bloom in their first year, flowering is stimulated, and seedless tomatoes and grapes can be obtained depending on the treatment. Gibberellins also accelerate bud burst in birch, chestnut, and linden trees.

Vitamins. Representatives of the genus Aspergillus accumulate significant amounts of thiamine and riboflavin within their Cells and release them into the environment. The synthesis of B-group vitamins (thiamine, biotin, pyridoxine, pantothenic, and nicotinic acids) has been detected in various species of Penicillium and Fusarium. The fungus Blakeslea trispora is a well-known producer of carotenes.