Transkingdom signaling systems between plant and its associated beneficial microbes in relation to plant growth and development

Abstract

The concept of plants being holobiont, suggesting a co-existence with their microbial symbionts has emerged only recently with increasing evidences, indicating the versatile role of plant associated microbes in the growth and development of a plant. Therefore plant is no longer considered a single entity but rather a metaorganism, a world of diverse interkingdom interactome. This has led researchers to focus on these associations, with a view to using them in agronomic interventions. Most of these microorganisms are either bacteria or fungi, residing in different parts of a plant, forming a mutualistic relationship with their host. They provide essential nutrients for the growth of plants and protect them against pathogens by acting as the plants' very own army. They allow for a plant's development even in the presence of pathogenic organisms, and also exert an effective role in rescuing plants from the detrimental effects of abiotic stressors. These microorganisms are therefore found to mitigate conditions non-conducive for plant growth. Plants in return, provide them with a secure habitat and adequate source of carbon in order for them to thrive. The interkingdom relationship has been found to be very systematic. Cross talk between the hosts and the benevolent guests is very specific, with particular signaling pathways giving advantage to some microorganisms over others, allowing for the creation of a specific niche. These signals that stimulate plant growth are a focus of intense biological research with more and more information being generated and our understanding of the role of a plant microbiome in overall plant health gradually becoming clearer. This chapter has focused on signaling strategies documented till date between microbes which have their own specific forte in and around a plant. An application of this knowledge would allow for the enhancement of crop production worldwide.