0026-2617/04/7301- © 2004 åÄIä “Nauka /Interperiodica” 0079 Microbiology, Vol. 73, No. 1, 2004, pp. 79–83. Translated from Mikrobiologiya, Vol. 73, No. 1, 2004, pp. 94–98. Original Russian Text Copyright © 2004 by Polyanskaya, Tolstikhina, Kochkina, Ivanushkina, Ozerskaya, Vedina, Zvyagintsev. Strains of the genus Trichoderma are widely applied in agriculture to control the development of pathogenic fungi in soil, rhizosphere, phyllosphere, and on seeds of various plants [1]; their application is also recom- mended for the protection of harvested crops [2–5]. The efficient employment of live microbial preparations depends on the ability of the introduced microorgan- isms to actively colonize the substrate. Conidia of fungi belonging to the genus Trichoderma are highly suitable for the production of dry preparations; however, it is necessary to know the conditions for conidium germi- nation in nature. The effect of environmental factors on the behavior of microbial populations has been exten- sively studied; it was shown that of particular ecologi- cal importance are intrapopulational interactions. Data have been published demonstrating the role of autoreg- ulation in the activation of resting forms of microorgan- isms [6, 7]. The aim of this work was to elucidate the intrapop- ulational regulation of conidium germination in differ- ent strains of the genus Trichoderma. MATERIALS AND METHODS The micromycete strains were isolated from the rhizospheres of roses (Grand Gala, Royal Velvet, and Dallas varieties). The four strains used in this work were typical representatives of the genus Trichoderma (table). To obtain conidia, micromycetes were cultivated on Czapek agar with sucrose (2%) at 26°ë for 7 days; conidia were washed off of the agar, centrifuged, washed thrice, and subjected to ultrasonic treatment on an UZDN-1 disintegrator at 22 kHz and 0.44 A for 30 s to obtain a suspension of single spores. Viability of the EXPERIMENTAL ARTICLES Autoregulation of Conidium Germination in Micromycetes of the genus Trichoderma L. M. Polyanskaya*, T. E. Tolstikhina*, G. A. Kochkina**, N. E. Ivanushkina**, S. M. Ozerskaya**, O.T. Vedina***, and D. G. Zvyagintsev* *Faculty of Soil Science, Moscow State University, Vorob’evy gory, Moscow, 119899 Russia **Skryabin Institute of Biochemistry and Physiology of Microorganisms, Russian Academy of Sciences, pr. Nauki 5, Pushchino, Moscow oblast, 142290 Russia ***Baicor, L.C., Logan, Utah, United States Received July 29, 2002 Abstract—The amount of germinated conidia of micromycetes belonging to the genus Trichoderma consider- ably decreased with an increase in the population density. Strains exhibited different ecological strategies. The maximum number of germinated conidia (30–70%) was recorded when the average distance between conidia was 50 μm. Key words: micromycetes, conidia. Strains tested Strain Species Author Isolation source Rose variety Anatomic part FW826 Trichoderma longibrachiatum Rifai 1969 Grand Gala Rhizosphere FW829 T. longibrachiatum Rifai 1969 Dallas Rhizoplane FW827 T. harzianum Rifai 1969 Royal Velvet Dead root FW828 T. harzianum Rifai 1969 Dallas Internal part of root