Author: Prof. Dr. Nikolay Vassilev – University of Granada
The majority of plants grow in soil.
Soil is the most complex natural ecosystem with highly complex characteristics, which includes microorganisms.
Soil microorganisms have a big impact on plant productivity by two main mechanisms:
- direct effects on plants via root-association that form mutualistic or pathogenic relationships with plants, and
- indirect effects via the action of free-living microbes that determine the rates of nutrient supply and the partitioning of resources.
It is well known that a gram of soil contains thousands of individual microbial taxa including bacteria, fungi, protists, and viruses. Many of them play the main role in ecosystem functioning determining soil fertility, plant growth promotion, and disease suppression.
However, after many years of chemical fertilization, soils lost their natural fertility, plant diversity and microbial richness. In addition, an increasing number of stress factors are observed such as salinity, alkalinity/acidity, contamination, nutrient deficiency or overload of chemical fertilizers, drought, soil erosion due to climate change, and various biotic factors.
The use of plant beneficial microorganisms to mitigate these problems in cultivated crop production is now a common practice particularly in the modern, sustainable agriculture and in the context of increasing world population and environmental and climate concerns. During the last 20–30 years, a large number of microorganisms have been isolated, characterized and tested as biofertilizers and biocontrol agents in controlled and natural conditions. The results confirmed the beneficial effect of the selected microorganisms on plant growth and health, enhancing nutrient content and improving soil properties.
Now, the emphasis of the scientific activity in the field of microbial inoculants is on developing environmentally friendly and efficient microbial formulations and analyse how the introduced microorganisms affect microbial community, diversity, and the specific plant– microorganisms interactions, which determine the plant holobiome functioning.
Therefore, at this moment, at least two major lines of research can be distinguished.
- The first one deals with holobiome/hologenome studies including molecular mechanisms and genetic regulation (and epigenetic mechanisms) of beneficial microbiota and,
- Another important line of research on the process of establishing a plant beneficial microbiome includes development of efficient single or multiple microbial inoculants.
On the other hand, a combination of pro- and postbiotics could be applied to manage and stimulate the existing beneficial microbiome.
These lines are in fact, the main Objectives of the EXCALIBUR Project.
The main purpose of the project is to improve the knowledge on soil biodiversity dynamics in relation to the different agro-ecological factors, for enhancing the efficacy and application of biocontrol and biofertilization practices.
To achieve this goal, Excalibur will identify and define how soil management strategies impact on applied inocula and autochthonous microorganisms present in soil and plant (endophytes). This will be paralleled by developing new bioproducts based on bio-inocula (innovative and multifunctional beneficial soil microorganisms) and bio-effectors (compounds or by-products which directly or indirectly enhance plant performance).
Inocula and bio-effectors will be tested and monitored on a number of key horticultural crops under conventional and organic management for their effects, the relations with native soil biodiversity and ecosystem services as well as their effects on crop production.
How we could relate this knowledge to the space issues?
First of all, the colonization of planets is impossible without microbial introduction and exploration of the existing extra-terrestrial microorganisms. The approach used in this process should mimic the process of converting our planet in habitable place by using the power of beneficial microorganisms, which even today sustain the life on Earth. Moreover, we are now studying the strong connection and transfer between plant-soil microorganisms and human microbiome.
An important primary need of the planet colonization is the generation of habitable atmosphere with decreased CO2 and more oxygen, which some microbes can produce.
Thereafter, another benefit would be to support growth of sustainable food supplies through symbiosis—e.g. nitrogen or carbon fixation to generate organic materials—and other ‘agriculture-beneficial’ mechanisms, to be further explored.
The questions we should answer are similar to those in EXCALIBUR: How to prepare or formulate the beneficial microorganisms in order to avoid the extreme conditions? How to combine different microorganisms in consortia? How the introduced microorganisms will affect the environment physically, chemically, and biologically?