Microbial products and soil stresses

Abstract

Plants are subjected to different types of stresses including salinity, drought, acidity, compaction, heavy metals, and suboptimal root zone temperature. There are some morphological and physiological mechanisms utilized by plant to alleviate the stress. Some plants are naturally tolerant to stress and some have been genetically modified to resist it. It has also been indicated that soil microbes including arbuscular mycorrhizal (AM) fungi and plant growth promoting rhizobacteria (PGPRs) have evolved some mechanisms, which usually results in the production of some compounds and hence alleviation of stress. Such compounds include different enzymes such as phosphatases (enhancing phosphorous availability), 1-aminocyclopropane-1-carboxylate (ACC)-deaminase (alleviation of ethylene stress on plant growth), different plant hormones, hydrogen cyanide (controlling pathogens), siderophores (nutrients chelators), glomalin (a glycoprotein improving soil structure), and lipochitooligosaccharides (inducing morphological changes in the host plant root, bacterial attachment to the roots, and improving soil structure). Recognition of such products can be important for the determination of microbial mechanisms under stress. Methods, such as the biotechnological ones, which may result in the enhancement of such products, can contribute to the increased plant performance, especially under stress.