Microbes already help feed the world. In fact, without microbes there would be no plants or animals, as all life on Earth is dependent on microbes to provide many essential services. In case of plants, vulnerable as they are to changes in their immediate environment, the services provided by microbes are critical. All plants are supported by a vast, invisible world of bacteria, viruses, and fungi that live in and around their roots, stems, leaves, seeds, pollen, fruits, and flowers to adapt the environment successfully.
Not only in plant but Additional complex communities of microbes live in and on the insects, birds, invertebrates, and other animals that interact with plants and with each other and help for betterment of organism in various ways.
The intimate relationship between Microbes and Agriculture
According to American Academy of microbiology, Washington, dc the Increase in our knowledge of plant-microbe interactions has deep implications for better agriculture. In past during domestication period of humans with plants and animals, there is no any knowledge about the local microbial communities and their importance to the health and productivity of those plants and animals.
Multiple strains of some staple food like wheat, corn, rice, and other crops have been planted around the world having different environments in sense of the local microbial communities compare to the original place of that crop, and where conditions are such that the plant might need new microbial partners to grow best.
Now a days it is most important to optimizing the microbial communities of plants offers an entirely new approach to enhancing productivity.
Why do plants need microbes…?
When anyone think about a crop, it seems straightforward to list the factors that affect their health and productivity: sunlight, water, temperatures, and fertile soil. But in nature, these factors are rarely found altogether at all times.
Now the question comes, How then do plants survive when one or another of these factors is absent or limited for some period of time? The answer is that there must some another, mostly invisible by nacked eyes, but crucially important, ingredient involved in the well-being of every plant or can called Microbes.
In fact every aspect of plant biology is affected by interactions with microbes. All plants strongly bound in multitude of relationships with many different kinds of microbes which are essential and enduring, while others are transient or needed only in certain circumstances.
A who’s who of microbial plant partners
As per biologist there are mainly three major groups of microbes associated with plants, which form the relationships with the plants may also be beneficial, neutral, or antagonistic.
Bacteria are fantastically abundant; there are up to 1010 bacterial cells per gram of soil in and around plant roots, a region known as the rhizosphere. Among the many services that bacteria can provide are: acquisition of nutrients and minerals; production of antibiotics to deter pathogens and toxins to deter pests; and production of hormones and other compounds to spur growth, stimulate the immune system, and modulate responses to stress.
It has recently become clear that the number and diversity of fungi associated with plants is more vast than previously appreciated. The fungi have been found in association with most plant tissues, living between and within plant cells, and forming extensive networks of which only some functions are known. Arbuscular mycorrhizae (AM) are found in association with the roots of 80% of land plants. .
Of the many microbes upon which plants are increasingly recognized as being dependent, perhaps viruses are the most surprising. Viruses are far and away the most numerous biological entities on Earth.
However, viruses were discovered because of their role in disease. Gradually, though, examples are accumulating of situations where viruses are not only beneficial, but may be essential to some plants. In some cases viral infection may be essential for survival under stressed conditions.
What kinds of services can Microbes provide?
Microbial activities are likely to be crucial to plant survival via one or more of the mechanisms described below.
Acquisition of nutrients
In addition to water, plants need nitrogen, phosphorous, potassium, sulfur, iron and other trace elements. Indeed, bacteria are the only known organisms that can transform gaseous nitrogen into an organic form, ammonia, that can be used by plants.
Plants can only absorb inorganic P (Pi). Both fungi and bacteria can help plants obtain adequate phosphorous. Other nutrients, like sulfur, potassium and iron can also be transformed into usable forms or transported to plants by both bacteria and fungi. Optimization of soil microbial communities could allow farmers to apply less chemical fertilizer, thus saving money and reducing the amount of excess nutrients that leach out of fields into water systems.
Pathogen and predator resistance
Partnerships with microbes can help plants resist pathogen threats.In the simplest case, When bacteria form a biofilm around the roots of a plant, microbial pathogens and soil–dwelling parasites cannot gain access.
Bacteriophage viruses that infect bacteria — may kill pathogenic bacteria directly. There is even evidence that microbes can generate electrical fields that can attract or deter other microbes and soil invertebrates like nematodes.
Surface and endophytic microbes also make a variety of potentially helpful compounds including toxins that deter grazers, volatile compounds that alert neighboring plants to the presence of a threat, and small molecules that trigger protective responses like the closing of stomata.
Resisting environmental stress
Microbes have been shown to be important partners in mitigating the effects of virtually every known environmental stress that can affect plants.
Acute plant viruses that under normal conditions cause disease have also been shown to improve drought tolerance in infected plants.
Many species of bacteria express the enzyme ACC deaminase, which degrades ACC, the precursor to ethylene. By blocking ethylene production, these microbes allow continued root development and increase plant growth in the presence of flooding or drought.
Fungal endophytes isolated from dune grass on the Pacific coast confer salt tolerance, as do some rhizobacteria, whose exopolysaccharide secretions potentially bind sodium and other cations, preventing their uptake by the plant.
■ Heavy metal contamination
Bacteria can both decrease toxicity of these metals and promote plant growth by sequestration of the metals themselves, rendering them biologically inactive, or also inhibiting the overall plant ethylene stress response through ACC deaminase activity.
■ Organic pollutant contamination
When soil is contaminated, a partnership between bacteria that can degrade or detoxify a compound that is inhibiting plant growth allows those bacteria to reproduce more rapidly. Moreover, their association with plant roots increases their access to pollutants due to pollutant movement to roots via the transpiration stream, and also helps transport these bacteria through the soil.
■ High temperatures
Some crops like potato grown in the presence of rhizobacteria exhibit increased root and shoot growth as well as increased tuberization under heat stress.
■ Low temperatures
Burkholderia species of bacteria have increased photosynthesis rates and decreased amounts of electrolyte leakage relative to control plants in cold temperatures.
Normal growth and development
Bacteria and fungi produce a number of phytohormones that increase root hair production, which increases the absorption capacity of the roots. Some seeds require bacteria to germinate.
Microbes can even affect the flavor of food plants. In strawberries, the methylo- trophic bacterium Methylobacterium extorquens enhances the production by the plant of chemicals called furanones that are responsible for the characteristic flavor of strawberries. One of these furanones — 2,5-dimethyl-4-hydroxy-2H-furanone (DMHF) — also stimulates plant defenses, increasing plant production of various antimicrobial compounds to deter harmful microbes.
Achieving food security for all plants, in all environments, depend on microbes, and therefore, potentially all crops, no matter where they are grown, could benefit from optimization of their microbial partners. The time is right to enlist the capabilities of the microbial world to help solve this pressing human problem.