Role of Endophytic Bacteria in Stress Tolerance of Agricultural Plants: Diversity of Microorganisms and Molecular Mechanisms

Abstract

Bacterial endophytes are a group of endosymbiotic microorganisms widespread among plants. An association of plants with endophytic bacteria includes a vast diversity of bacterial taxa and host plants. In this review we present an overview of taxonomic composition of the bacterial endophytes identified in common agricultural crops with special emphasis on the most recent results obtained using metagenomic analysis. Endophytic microbiome constitutes a part of larger soil microbial community and is susceptible to direct or indirect effect of agricultural practices: soil tillage, irrigation, use of pesticides and fertilizers has a major effect on function and structure of soil and endophytic microbial populations. Therefore, the use of agricultural practices that maintain natural diversity of plant endophytic bacteria becomes important element of sustainable agriculture that ensures plant productivity and quality of agricultural production. On the other hand, the endophytic microbiome itself have been shown to have multiple effects on their host plant, including modulation of phytohormone signaling, metabolic activity, and plant defense response pathways. It has been demonstrated that these effects could be helpful for plant adaptation to abiotic or biotic stresses. Therefore, application of endophytic bacteria to improve crop performance under cold, drought, salinity, and heavy metal contamination stress conditions or to enhance disease resistance presents an important potential for sustainable agricultural production.