Microbiomes and Plant Health

Panoply and Their Applications

Manoj Kumar Solanki,Prem Lal Kashyap,Rizwan Ali Ansari,Baby Kumari

• Publisher: Academic Press
• Year: 2020
• ISBN:
  9780128226018
• Topic: Sciences biologiques
• Subtopic: Botanique

Microbiomes and Plant Health: Panoply and Their Applications includes the most recent advances in phytobiome research. The book emphasizes the use of modern molecular tools such as smart delivery systems for microbiol inoculation, next-generation sequencing, and genome mapping. Chapters discuss a variety of applications and examples, including the sugarcane microbiome, rhizoengineering, nutrient recycling, sustainable agricultural practices and bio-potential of herbal medicinal plants. Written by a range of experts with real-world practical insights, this title is sure to be an essential read for plant and soil microbiologists, phytopathologists, agronomists, and researchers interested in sustainable forestry and agriculture practices.

• Offers readers a one-stop resource on the topic of plant and soil microbiome and their applications in plant disease, sustainable agriculture, soil health and medicinal plants
• Addresses the role of phytobiome to combat biotic and abiotic factors
• Emphasizes the use of modern molecular tools such as smart delivery systems for microbial inoculation, next-generation sequencing and genome mapping

Part I

Introduction Part

Outline

• 1 Emerging insights on the potential role of plant-associated microorganisms in sustainable agriculture
• 2 Application of cereal and vegetable endophytes in plant health management
• 3 Plant virome: current understanding, mechanisms, and role in phytobiome

1

Emerging insights on the potential role of plant-associated microorganisms in sustainable agriculture

Silju Juby, P. Jishma and E.K. Radhakrishnan, School of Biosciences, Mahatma Gandhi University, PD Hills (PO), Kottayam, India

Abstract

Enhanced chemical input in the agricultural field for the increased crop yield and plant disease management has resulted in the development of the resistant form of phytopathogens, loss of soil structure and fertility, and harmful effect on the ecosystem and human health. At this point, there is a necessity of sustainable alternative methods to compensate issues with injudicious use of agrochemicals. Application of plant beneficial microorganisms executed in the form of biofertilizer and biocontrol agents hence has significant application. Most remarkably, plant microbiome is unique in their biosynthetic potential, antimicrobial, and plant beneficial properties and hence has immense promises to boost agricultural production. This chapter mainly focused on multifaceted applications of plant-associated microorganisms including plant growth promotion, biocontrol properties, stress tolerance, and bioremediation.

Keywords

Microbiome; endophytes; plant growth-promoting bacteria; rhizosphere; phyllosphere; biofertilizer; biocontrol agent; induce systemic resistance

1.1 Introduction

Plant microbiome is an important association in the ecosystem and is the set of genomes of the microorganisms associated with plants (Bulgarelli et al., 2013; Mueller and Sachs, 2015). The microbiome has been known to be involved in crucial functions such as immunologic, hormonal, and metabolic homeostasis of their host. Each plant can host up to several thousands of microorganisms in their different parts (Berendsen et al., 2012). All plants have their own associated microbiome, which affects plant health and growth predominantly in a beneficial way. Plant microbiome also provides an additional pool of genes that plants can access for the functioning of the plant system under different conditions. In the fluctuating climatic and environmental conditions, plants face several challenges in nutrient acquisition, defense against pathogens and herbivores, and in the tolerance to abiotic stresses such as drought, pollutants, and salinity. The plant microbiome provides an adaptive environment to manage such challenges. Plant and its associated microorganisms live in a symbiotic manner, that is, the microbes positively influence the plant growth by supplying nutrients and providing stress tolerance from phytopathogens. At the same time, each microbe get advantage from their host by receiving easily degradable carbon, a protected environment and physical structures for its colonization. The plant-associated microorganisms can generally be in the form of epiphytes or endophytes (Newman and Cragg, 2015). Epiphytic organisms found outside the plant surface while endophytes present inside the tissues. Epiphytes reside permanently or casually on the surface of the plant (Kumar et al., 2017a). Epiphytes live on the surface of any part of plant-like leaves, roots, flowers, seeds, stem, buds, and fruits, and the pattern of microbial distribution and its colonization can be controlled by the host plant. Generally, microorganisms that live on the aboveground parts of the plant are referred to as phyllosphere microorganisms and microorganisms associated with the root system are referred to as the rhizosphere microorganisms (Fig. 1.1). Endophytes live inside the plant tissue for at least a part of its life cycle without causing any harmful effect to the host and it is seen in every plant species studied to date. But the relationship among the endophyte and host plant remains a complex process.

Figure 1.1 Phyllosphere and rhizosphere represented in a typical plant.

Phytopathogens are major challenges to agricultural productivity, which affect the growth and health of the plants and crop yield. This enhances the application of the unsustainable level of agrochemical inputs, which leads to the production of chemically contaminated and low-quality crops. Consumption of such contaminated food products causes health issues and environmental toxicity. In the current scenario, plant-associated microorganisms are identified as beneficial candidates for the control of plant diseases and enhanced productivity. This ecologically compatible and eco-friendly approach is capable of providing adequate solutions for improving agriculture productivity.

1.2 Plant habitat for colonization of microorganisms

Microorganisms colonize different parts of plants and it determines the specific biosynthetic property of the associated microorganisms. Phyllosphere consists of the total aerial parts of plants which can be subdivided into caulosphere, phylloplane, anthosphere, or carposphere. The total surface area of the phyllosphere is high enough to provide habitat for numerous microorganisms to colonize the leaf surfaces and the spaces inside leaves. Numerous biotic and abiotic determinants drive the microbial structure in the phyllosphere. In general, the phyllosphere of plants is get colonized by diverse microorganisms such as bacteria, yeasts, fungi, algae, and less often by protozoa and nematodes. Bacteria are the most abundant inhabitants in the phyllosphere and fungi present predominantly as spores (Andrews and Harris, 2000). Among all parts, leaves comprise a very large microbial territory and the estimated surface area of terrestrial leaves that are colonized by microorganisms is 6.4×10⁸ km^{2 (}Lodewyckx et al., 2002).

The term “endophyte” is originated from the Greek words “endon” (within) and “phyton” (plant) (Wilson, 1995; Hardoim et al., 2015). Endophytic microbes including bacteria, archaea, fungi, and protists colonize the plant interior despite the outcome of the association. Even though they are living inside the tissues, they do not have any parasitic effects on the host plant generally (Strobel and Daisy, 2003). Endophytes pose different impacts on the host plant. They are found to promote plant growth and provide tolerance to biotic and abiotic stresses (Gaiero et al., 2013).

The rhizosphere is another important zone related to the plant roots, which is the region of soil ...