Bacterial influencers -- rhizosphere microbiome mediates root metabolite exudation

February 07, 2020

Gatersleben, 07.02.2020 Roots are plant organs, that typically absorb water and minerals from soil. It is lesser known that roots also secrete metabolites, so-called root exudates, which impact the properties of soil directly around the root. This thin layer of soil is called the rhizosphere and is home to a rich microbial diversity, the root microbiota. By producing certain exudates, plants communicate with and govern the microbial life within their rhizosphere for their own benefit. Now, researchers have discovered that this is not a one-way process. Whilst investigating tomato plants, they found that the microbiota can also systemically shape and control root exudation.

When thinking of ecological hotspots, roots and the earth surrounding them might not immediately spring to mind. However, precisely this region, the rhizosphere, is considered as one of the most complex ecosystems found on earth. It harbours a divers microbiotic community, including numerous bacteria, fungi and archaea, thriving in an environment rich in biochemical compounds, that are exuded by plant roots at the core of the rhizosphere.

Plants govern the rhizosphere microbiota and shape the soil physical and chemical properties through their root exudates. At the same time, it is well known that roots sense changes in the rhizosphere and trigger systemic responses to defend against pathogens or to adjust to changes in nutrient availability. Nonetheless, there are still many open questions regarding the dynamics and impact of the microbiota on the root itself, and it was not clear how, or whether at all, the rhizosphere microbiota affects the root exudation. An international research team led by Dr. Elisa Korenblum, a scientist from the Weizmann Institute of Science in Israel in collaboration with Dr. Jedrzej Szymanski from the Leibniz Institute IPK in Gatersleben, recently took on this question whilst investigating roots of tomato plants.

Dr Korenblum and her team conducted and analysed a row of split-root experiments, where half of roots of each plant was exposed to a microbiome-rich soil, and the other half was grown in sterile and biochemically ambient conditions. This enabled them to investigate the effect of different microbial communities on the local root system, as well as the systemic changes in the distant roots in anticipation of the presence of new microorganisms. Dr. Szymanski, head of the Network Analysis and Modelling group, traced the complex network of biochemical and gene expression signals controlling this microbiome-root communication and their propagation from the place of origin to distant roots. They thereby discovered that the tomato rhizosphere microbiome can directly affect the chemical composition of roots and root exudates via a systemic root-to-root signalling mechanism. For example, bacteria of the genus Bacillus use this process, which the scientists termed Systemically Induced Root Exudation of Metabolites (SIREM), to trigger the secretion of acylsugars in the whole root system.

The discovery of SIREM is a first step towards untangling the regulatory network spanning the complex plant root-microbial relationship. It is likely that the SIREM process is a key feature of root-microbiota interactions within the rhizosphere, and that the microbiome-reprogrammed systemic root exudation promotes soil conditioning. The precise extent of the regulatory role and incidence of SIREM is yet to be determined.
-end-


Leibniz Institute of Plant Genetics and Crop Plant Research

Related Microbiota Articles from Brightsurf:

Glyphosate may affect human gut microbiota
More than half of bacterial species in the core of the human gut microbiome are potentially sensitive to glyphosate, shows new research.

The gut microbiota forms a molecule that can contribute to diabetes progression
It is the bacterial changes in the gut that increase the levels of imidazole propionate, the molecule that makes the body's cells resistant to insulin in type 2 diabetes.

Link between Alzheimer's disease and gut microbiota is confirmed
In recent years, the scientific community has suspected that the gut microbiota plays a role in the development of the disease.

Multi-mucus barrier segregates colon microbiota from host tissue
Whole-colon imaging in mice has revealed a continuous colonic mucus system, which forms a protective barrier between potentially harmful gut microbiota and host tissue by encapsulating fecal pellets as they form and as they are eliminated from the colon.

Fecal transplantation can restore the gut microbiota of C-section babies
Birth by Cesarean section is detrimental to normal gut microbiota development.

Feeding C-section newborns their mother's poop may help build healthy microbiota
A paper published October 1, 2020 in the journal Cell suggests that newborns delivered by cesarean may benefit from drinking a small amount of their mother's feces dissolved in breast milk, because it provides them with beneficial bacteria they would otherwise be exposed to in vaginal birth.

Stronger bones thanks to heat and microbiota
Osteoporosis is characterised by a deterioration of the bones and an increased risk of fractures.

Gut microbiota not involved in the incidence of gestational diabetes mellitus
Consuming the combination of fish oil and probiotic food supplements modulate the composition of gut microbiota in overweight and obese pregnant women, reveals a new study conducted at the University of Turku, Finland.

Studies of gut microbiota and contractility help deal with chronic constipation
Chronic constipation (CC) remains a serious medical and social problem because the complexity of diagnosis, the lack of a single approach to treatment, and unsatisfactory treatment results.

Penis microbiota predicts if a man's female partner will develop bacterial vaginosis
Penile microbiome composition can vary; however, the presence of some bacterial vaginosis-related bacteria correlates with bacterial vaginosis onset in their female partners.

Read More: Microbiota News and Microbiota Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.