Abstract
Mechanisms governing plant–microbe interaction in the rhizosphere attracted a lot of investigative attention in the last decade. The rhizosphere is not simply a source of nutrients and support for the plants; it is rather an ecosystem teeming with diverse flora and fauna including different groups of microbes that are useful as well as harmful for the plants. Plant–microbe interaction occurs via a highly complex communication network that involves sophisticated machinery for the recognition of friend and foe at both sides. On the other hand, nitric oxide (NO) is a key, signaling molecule involved in plant development and defense. Studies on legume–rhizobia symbiosis suggest the involvement of NO during recognition, root hair curling, development of infection threads, nodule development, and nodule senescence. A similar role of NO is also suggested in the case of plant interaction with the mycorrhizal fungi. Another, insight into the plant–microbe interaction in the rhizosphere comes from the recognition of pathogen-associated molecular patterns (PAMPs)/microbe-associated molecular patterns (MAMPs) by the host plant and thereby NO-mediated activation of the defense signaling cascade. Thus, NO plays a major role in mediating the communication between plants and microbes in the rhizosphere. Interestingly, reports suggesting the role of silicon in increasing the number of nodules, enhancing nitrogen fixation, and also the combined effect of silicon and NO may indicate a possibility of their interaction in mediating microbial communication underground. However, the exact role of NO in mediating plant–microbe interaction remains elusive. Therefore, understanding the role of NO in underground plant physiology is very important, especially in relation to the plant’s interaction with the rhizospheric microbiome. This will help devise new strategies for protection against phytopathogens and enhancing plant productivity by promoting symbiotic interaction. This review focuses on the role of NO in plant–microbe communication underground.
Highlights
Plants develop a close association with the microorganisms inhabiting the areas in and around the roots which are influenced by the chemicals released from the plant roots
Rhizosphere is the area around a plant root inhabited by a diverse population of microorganisms; only the unique population can influence or can be influenced by the chemical signals released by either of them
Bacteria and plants share several features of NOproducing pathways which suggests that nitric oxide (NO) acts as a signaling molecule during plant–microbe association
Summary
Plants develop a close association with the microorganisms inhabiting the areas in and around the roots which are influenced by the chemicals (and/or enzymes) released from the plant roots. Needs to be converted to a non-toxic and ubiquitous form This is accomplished by the covalent attachment of NO group (–NO) to exposed cysteine thiols to form S-nitrosothiols (SNOs), a process termed S-nitrosation which is a highly ubiquitous posttranslational modification of proteins with diverse regulatory roles across the different kingdoms of life. These SNOs serve as mobile reservoirs, providing a sustained supply of NO in vivo, playing key roles in plant physiology under basal as well as stress conditions. The Cellular GSNO levels are controlled by an evolutionarily conserved cytosolic enzyme GSNO reductase 1 (GSNOR1)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
