Influence of root exometabolites of various sunflower hybrids on the growth and development of fungus Alternaria alternata (Fr.) Keiss

Abstract

Phytopathogenic microorganisms — excitants of sunflower diseases are one of the major biotic factors in reducing of the biosafety of plant productions. The high allelopathic potential of plants of this culture actively influences both competitive plants and pathogenic microorganisms that colonize it. The fungi of the genus Alternaria Nees are dangerous phytopathogenic species that parasitize during ontogenesis on the sunflower plants and seeds. The sunflower seeds and plants affect can lead to increasing of their crop and quality losses both during plants vegetation and seeds storage. The fungi of this genus form about 70 types of myco- and phytotoxins, among which there are the dangerous for human and animal health: alternariol, alertoxin and alternariol monomethyl ether. The results of estimation of exometabolites influence of sunflower hybrids: Dushko, Oliver and Oscar on growth and development of Alternari alternata (Fr.) Keiss. are presented. It has been established that exometabolites of different hybrids of sunflower plants can both suppress and stimulate the rate of mycelium radial growth of phytopathogenic fungi depending on the hybrid and the technology of its cultivation. The results suggest that the root exombetabolites of Dushko and Oliver hybrids have a higher antifungal activity in comparison with the Oscars hybrids under the traditional plant cultivation technology. At the same time, the antifungal properties of the root exometabolites of different hybrids of sunflower plants, which have been grown by organic technology, have the ability to restrain the growth and development of mycelium fungus more closely than it is grown under traditional technology. According to the results of the research, bacteria of the genus Micrococcus spp., which colonized of the A. alternata colonies, were identified.These bacteria have the ability to form of the stable associations with plants and can participate in their resistance to the harmful effects of phytopathogenic microorganisms, as well as are able to promote the growth and development of plants.