Bacterial Endophyte Colonization and Distribution within Plants

Abstract

The plant endosphere contains a diverse group of microbial communities. There is general consensus that these microbial communities make significant contributions to plant health. Both recently adopted genomic approaches and classical microbiology techniques continue to develop the science of plant-microbe interactions. Endophytes are microbial symbionts residing within the plant for the majority of their life cycle without any detrimental impact to the host plant. The use of these natural symbionts offers an opportunity to maximize crop productivity while reducing the environmental impacts of agriculture. Endophytes promote plant growth through nitrogen fixation, phytohormone production, nutrient acquisition, and by conferring tolerance to abiotic and biotic stresses. Colonization by endophytes is crucial for providing these benefits to the host plant. Endophytic colonization refers to the entry, growth and multiplication of endophyte populations within the host plant. Lately, plant microbiome research has gained considerable attention but the mechanism allowing plants to recruit endophytes is largely unknown. This review summarizes currently available knowledge about endophytic colonization by bacteria in various plant species, and specifically discusses the colonization of maize plants by Populus endophytes.

Review: Endophytic microbes and their potential applications in crop management

“…It is unknown what is produced or degraded by the intracellular microbes to initiate the gravitropic response in seedling roots. Endophytic microbes in plants have also been shown to enhance root growth and increase root branching, further leading to increased plant growth . These effects of endophytes on root growth are generally attributed to production of growth regulators by microbes; however, enhanced nutrient acquisition from microbes may equally contribute to enhanced plant growth.…”

“…An endophyte is any microbe (typically fungal or bacterial) that inhabits internal tissues of plants without causing disease . All or most plants possess endophytes, and in most cases endophytes are seed transmitted and begin to promote growth and plant health as soon as seeds germinate .…”

Paraburkholderia phytofirmans PsJN-Plants Interaction: From Perception to the Induced Mechanisms

“…The secretion of root exudates by the plant initiates the first communication between endophytes and host plants (Kandel et al, 2017). Moreover, quorum sensing compounds produced by strain PsJN play an important role in host communication, and the subsequent colonization process (Zúñiga et al, 2017).…”

Efficient colonization of the endophytes Herbaspirillum huttiense RCA24 and Enterobacter cloacae RCA25 influences the physiological parameters of Oryza sativa L. cv. Baldo rice

“…Bacterial endophytes initially stick to the root surface and explore the potential entry sites to access the internal plant tissues. Opening in the roots, where root hairs or lateral roots emerge, as well as wounds in the shoots, are considered the main entry points that endophytes use to enter the host plant and access its internal tissues (Mercado-Blanco and Prieto, 2012;Compant et al, 2016;Kandel et al, 2017). Therein, they reside for most of their life with no detrimental impact to the host plant (Mercado-Blanco and Lugtenberg, 2014;Hardoim et al, 2015).…”

“…Therein, they reside for most of their life with no detrimental impact to the host plant (Mercado-Blanco and Lugtenberg, 2014;Hardoim et al, 2015). The internal plant tissues constitute a favourable environment for N-fixation performed by diazotrophic endophytes: the competition with other microbes in the rhizosphere is minimized and a microaerobic environment, necessary for nitrogenase activity, is provided (Mus et al, 2016;Kandel et al, 2017). In the last few years, a wide diversity of bacteria associated with cereals have shown to possess the nifH gene coding for dinitrogenase reductase (Rosenblueth et al, 2018).…”