How Do Microbes Contribute To Plant Growth?
4 Aug 2022

How Do Microbes Contribute To Plant Growth?

Anjali Singh, MS

As a content and community manager, I leverage my expertise in plant biotechnology, passion for tissue culture, and writing skills to create compelling articles, simplifying intricate scientific concepts, and address your inquiries. As a dedicated science communicator, I strive to spark curiosity and foster a love for science in my audience.

Anjali Singh, MS
Table of Contents

There are also some microbes that are friendly to plants, help them develop and grow, avail them of nutrients, and help them to fight pathogens like harmful bacteria and viruses.


You would have all your life that microbes are bad for plant health, they infect, rot, and kill the plants. But, do you know, not all microbes are of this kind?

There are also some microbes that are friendly to plants, help them develop and grow, avail them of nutrients, and help them to fight pathogens like harmful bacteria and viruses.

As a human body is home to microbes that help in our metabolic processes, such as digestion, plants also make relation with the good microbes living in soil. They both help each other to thrive and grow.

The microbial relation with plants can be explained in three ways:

  • Negative: Relation with harmful and pathogenic bacteria that infect and hinder plants’ growth and development. They multiply and spread inside plants and ultimately kill them.
  • Positive: The plant-friendly microbes help plants to grow and develop and fight with phytopathogenic microbes, such as fungi, viruses, and other bacteria. In return, plants feed these bacteria with vitamins, carbohydrates, and organic acids. These microbes are also known as plant growth promoting microbes.
  • Neutral: Some microbes live near or within the plants but then neither benefit them nor harm them.

In this article, we will cover what microbes are plant-friendly and how they help plants in fighting the pathogens or take up nutrients. Moreover, we will also learn if they can be used in tissue culture or not.

What are Plant Growth Promoting Microbes (PGPMs)?

Any microbes that help the plant to grow and fight with diseases and recover from biotic and abiotic stresses are known as plant growth promoting microbes.

The PGPMs living in soil either live near the root surface or inside the plant tissues (known as endophytes). These microbes play a host of functions in terms of supporting plant growth, ranging from iron chelation, nitrogen fixation, mineral solubilizing (Zn, P, and K), and phytohormones.

They influence almost all aspects of plants’ life, including in nutrition, growth, seed germination, and biotic and abiotic stresses.

Based of their functions and growth promoting mechanism, we can categories these plant growth promoting microbes in three groups:

  • Biofertilizers: They increase the availability and uptake of nutrients to plants. They provide macro and micro nutrients.
  • Biocontrol agents: They produce antimicrobial metabolites to protect plants against pathogens. Moreover, they also fight pathogens for nutrients and space.
  • Biostimulants: They are also known as phytostimulants. They produce useful substances for plants such as plant growth regulators.

Figure: A schematic representation of all the roles played by different groups of plant growth promoting microbes.

However, there are also some plant growth promoting microbes that support plant growth by using 2-3 growth promoting mechanisms.

Based on the types of microbial forms, plant growth promoting microbes are of two types:

  • Plant growth promoting fungi (PGPF): It include: arbuscular mycorrhizal fungi (e.g., Gigaspora, Funneliformis, and Rhizophagus), ericoid mycorrhizal fungi (Harpophora oryzae, and Colletotrichum tofieldiae), orchid mycorrhizal fungi (Russula, Rhizoctonia, and Tulasnella species), ectomycorrhizal fungi (e.g., Laccaria, Pisolithus, and Scleroderma), and root endophytes fungi such as Fusarium spp., Penicillium spp., Aspergillus spp.
  • Plant growth promoting bacteria (PGPB): It includes different types of bacteria such as associative, free-living bacteria, nodule forming bacteria, and endophytes. Their examples include Bacillus, Azospirillum, Thiobacillus, Frankia, Burkholderia, Pseudomonas, Rhizobium, Bradyrhizobium, Serratia, and Streptomyces.

Can Plant Growth Promoting Microbes Help in Tissue Culture?

Yes! These microbes do have potential to promote growth under in vitro conditions. However, it’s under research and not enough data is present at the moment to say what microbes can help in what ways.

However, there are certain studies available mentioning the roles of these microbes in different stages of tissue culture. Some of them are given below:

  • Water stress is a common problem in tissue culture plants because of the low absorption capacity of their roots. Thus, in this case, inoculating plants with arbuscular mycorrhizal fungi (AMF) is an effective tool to solve this problem. The fungi also increase the micronutrient uptake of plants, such as P, Zn, Cu, Fe, etc.
  • In stages II and III, these beneficial microbes act as biostimulants and help in increasing the length of the plants’ shoots and increase rooting.
  • While at stage IV, they act as biocontrol agents that help the plants to deal with biotic and abiotic factors.
  • Some microbes also help in the production of plant growth regulators such as auxin, cytokinin, and gibberellins which are crucial for the growth and development of plants.
  • Some reports suggest that inoculating tissue culture plants with microbes helps in increasing their survival rate and chances during the acclimatization stage.


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