[Molecular genetic mechanisms used by legumes to control early stages of mutually beneficial (mutualistic) symbiosis].

Recent data on the plant control of early stages of mutually beneficial (mutualistic) symbioses of legumes, the mechanisms of perception and transmission of the microsymbiont's molecular signals in the macrosymbiont's cells, and induction of the genetic programs of the development of symbiotic compartments and organs of the plant are summarized. It is demonstrated that the genetic system of the plant controlling the development of nitrogen-fixing symbiosis of legumes (symbiotic root nodules), which emerged 70-80 Ma ago, has undoubtedly evolved on the basis of the genetic system controlling the development of the symbiosis with arbuscular mycorrhizal fungi (which emerged 40-500 Ma ago. Interactions between genes and between gene products, as well as exchange of molecular signals, form the basis of mutually beneficial (mutualistic) plant-bacterium interactions. Even in the case of a highly specific nitrogen-fixing symbiosis of legumes (symbiotic nodules), the receptors perceiving the signal from root-nodule bacteria may function in different ways. The development of arbuscular mycorrhiza and nitrogen-fixing symbiosis in legumes is a multistep process involving hundreds of genes of both the macro- and microsymbionts. For the symbioses to develop successfully, these genes should act in a coordinated way in the newly formed superorganismal system. Further studies are necessary to shed light onto the complexity of the plant genetic control of the development of mutualistic symbioses in legumes and provide information required for improving their functions in adaptive plant-breeding systems.

[Regulatory genes of garden pea (Pisum sativum L.) controlling the development of nitrogen-fixing nodules and arbuscular mycorrhiza: a review of basic and applied aspects].

The review sums up the long experience of the authors and other researchers in studying the genetic system of garden pea (Pisum sativum L.), which controls sthe development of nitrogen-fixing symbiosis and arbuscular mycorrhiza. A justified phenotypic classification of pea mutants is presented. Progress in identifying and cloning symbiotic genes is adequately reflected. The feasibility of using double inoculation as a means of increasing the plant productivity is demonstrated, in which the potential of a tripartite symbiotic system (pea plants-root nodule bacteria-arbuscular mycorrhiza) is mobilized.

[The production of antifungal metabolites by Pseudomonas chlororaphis grown on different nutrient sources]. / Produtsirovanie antifungal'nykh metabolitov Pseudomonas chlororaphis pri roste na razlichnykh istochnikakh pitaniia.

It was found that the antifungal activity of Pseudomonas chlororaphis SPB1217 is due to phenazine-1-carboxylic acid, phenazine-1-carboxamide, and two unidentified exometabolites. The carbon source used for the growth of this bacterial strain and iron ions present in the medium considerably influenced the proportion between the antifungal metabolites. The maximum production of phenazines was observed in the media enriched in amino acids and iron ions. The absence of correlation between the production of phenazines and antifungal activity indicates that phenazines are not the only antifungal metabolites of the strain. Organic acids as nutrient sources provide for more intense production of exometabolites and for a higher level of antifungal activity than do sugars.