Relationship between the Composition of Root Exsudates and the Efficiency of Interaction of Wheat Plants with Microorganisms

Abstract

Plant roots secrete various organic substances into the rhizosphere, which are a source of nutrition for microorganisms and largely determine the nature of plant-microbe interactions. The composition of the main fractions of root exudates in ten modern varieties of wheat was determined: amino acids, organic acids and sugars. Reliable qualitative and quantitative differences between varieties for individual components of exudates were revealed, which determined the peculiarities of cultivar clustering on this trait. Relationships between exudation and the effectiveness of plant interaction with the growth-promoting rhizobacterium Pseudomonas fluorescens SPB2137 and the phytopathogenic fungus Fusarium culmorum 30 in laboratory systems, as well as with the resistance of varieties to diseases in the field, were found. The number of P. fluorescens SPB2137 in the root zone positively correlated with the amount of many amino acids, as well as maltose, secreted by the roots. The stimulating effect of rhizobacteria on root growth positively correlated with the amount of released glucose and melibiose. The relationship between the nature of root exudation and root colonization or the susceptibility of varieties to F. culmorum 30 was not found. The analysis of correlations between the incidence of wheat varieties in the field and the intensity of exudation of certain substances, as well as with the biocomposition index of amino acid exudation, was carried out. The role of root exudate components in the formation of effective plant-microbial systems is discussed.