Plant Root Secretions and Their Interactions with Neighbors

Abstract

The rhizosphere biology at the molecular level has advanced dramatically since last decade. The continuous supply of carbon compounds from plant roots engages complex interactions among rhizosphere organisms including interactions between microbes and plants and between plants with other plants being these of the same or different species. Root exudation is part of the rhizodeposition process, which is a major source of soil organic carbon released by plant roots which clearly represents a significant carbon cost to the plant. Root exudates also play a role in soil nutrient availability by altering soil chemistry and soil biological processes. Different studies have highlighted that the rhizosphere soil surrounded by plant roots is more abundant in microbes than the nonrhizosphere soils. Therefore, the major responses in the interaction between plants and microbes must happen in that limited zone. Plants respond to the presence of microbes by releasing a mixture of phytochemicals, volatiles, and high-molecular-weight compounds. Soil microbes, on the other hand, modulate the secretion of root exudates to positively regulate plant growth and disease resistance. Several negative interactions are mediated by root exudates including antimicrobial, biofilm inhibitors, and quorum-sensing mimics to prevent soil-borne pathogens. There is a need to understand these rhizospheric multitrophic interactions in the realistic field conditions to improve the plant growth at species and community level. In addition, studies should be conducted in the field C. De-la-Peña

The Hidden Chemical Cross-Talk Between Roots and Microbes: A Proteomic Approach

“…Roots are at the very first line of defense of the plants in the soil microbiota. In order to achieve this function, roots secrete a wide variety of molecules into the rhizosphere, many of which are proteins [4]. Among the secreted proteins, we can find those involved in defense, as well as proteins implicated in signaling and regulatory processes [14] (Fig.…”

“…These interactions can be grouped based on the nature of the interacting organisms, such as plant-plant, plant-microbe, microbe-microbe, microbe-fauna, plant-fauna, etc. [4]. Many of these indirect interactions have been studied using proteomics, which together with genomics, transcriptomics and metabolomics, are part of the "omics" family.…”

“…Recently, it has been proposed that plants can constitutively secrete a large variety of proteins to protect their roots from the environment [3]. These proteins, made mainly from photosynthetically fixed carbon, are directly released as root exudates, a major factor in regulating soil microbiota [4]. Recently, it has been proposed that carbon and nitrogen flow at the soil-root interface is bidirectional [5].…”

Possibility of Allelopathic and Residues Effects of the Rotated Crops on Productivity, Chemical Composition, Nitrogen Utilization of Wheat (Triticum aestivum) and Soil Fertility

“…Root exudation is an element of the rhizodeposition process, which is a major source of soil organic carbon released by plant roots [10,11]. Upon assembling a challenge, roots typically respond by secreting certain small molecules and proteins [12,13]. Root secretions may play both positive and negative communication in the rhizosphere.…”

Biotic Interactions in the Rhizosphere: A Diverse Cooperative Enterprise for Plant Productivity

“…There are many chemicals secreted from microorganisms and roots, such as amino acids, organic acids, flavonols, glucosinolates, indole compounds, fatty acids, polysaccharides, and proteins in the rhizosphere (De-la-Peña et al, 2012a;Nguema-Ona et al, 2013;Weston et al, 2013;Li et al, 2014;Talboys et al, 2014;Zhang et al, 2014), that act as signals; once the recipient organisms recognize them, the process of communication and interaction begins. The type and composition of root secretion can alter the microbial dynamic and diversity of the soil, favoring the growth of microorganisms that can benefit plant health and crop productivity, while, in other cases, root-exuded compounds prevent the growth of harmful microbes (Bais et al, 2006;Chaparro et al, 2012;Dutta et al, 2013;Li et al, 2013).…”