The Root of Diversity: How Root Exudates Are Influencing Food Security

Microorganisms play a crucial role in the health and productivity of plants, and the composition of these microorganisms can be affected by various factors such as cultivation practices, plant age, and breeding.

In this article, we will explore how agriculture and breeding can change the microbial diversity and root exudates of plants, and how these changes can affect the ability of plants to recruit beneficial microorganisms.

Root exudates: often overlooked aspect could hold the key to 
feed the world SUSTAINABLY!        

Agriculture and Microbial Diversity

Cultivated and Uncultivated Land:

Microbial diversity in soil is crucial for maintaining ecosystem functions and is known to differ between cultivated and uncultivated land. Studies have shown that compared to uncultivated land, cultivated land has a lower microbial diversity. For example, a study by Smith et al. (2018) found that the microbial diversity in cultivated soils was 27% lower than in uncultivated soils. Another study by Lauber et al. (2009) found that the bacterial diversity in cultivated soils was 50% lower than in uncultivated soils.

Crop Influence:

However, the specific microbes present in cultivated land can depend on the type of crop being grown and the cultivation practices being used. For example, another study found that the microbial community in soil under a monoculture of corn was less diverse than in soil under a polyculture of corn and soybeans.

The lower microbial diversity in cultivated land can have negative effects on plant health and productivity. For example, lower microbial diversity has been associated with reduced nutrient availability and increased susceptibility to pathogens

Commercial cultivation as we know it could be like 
stacking the deck against us and then trying to win the odds.
We are set for failure!        

Too much of one thing...

Monoculture, the practice of growing a single crop species in a field, can also affect the root exudate composition of plants. Monoculture can lead to a decrease in microbial diversity in the soil, which in turn can affect the plant's ability to recruit specific microorganisms for the association. A study by Berendsen et al. (2012) found that compared to a diverse crop rotation, a monoculture of winter wheat (Triticum aestivum) had a lower diversity of root-associated bacteria.

When plant age is not just a number for root exudates

Root exudates are compounds released by plants into the soil that can influence the composition of the microbial community. As plants grow and age, their root exudate composition also changes. For example, young plants tend to exude more sugars, amino acids, and other organic compounds that support the growth of microorganisms in the early stages of plant development. As plants mature, the composition of root exudates shifts towards compounds that support the plant's growth and reproduction, such as phytohormones and secondary metabolites. A study by Liu et al. (2018) found that the root exudates of young rice plants (Oryza sativa) had higher levels of sugars and amino acids, while mature rice plants had higher levels of phytohormones and secondary metabolites.

Stressing it out

Plant stress can lead to changes in the composition of root exudates, which in turn can alter the plant's ability to interact with the soil microbiome. When plants are under stress, certain secondary metabolites, such as flavonoids and phytohormones, which can act as signaling molecules to recruit specific microorganisms for association. For example, a study by Mhamdi et al. (2015) found that under drought stress, Medicago truncatula (a model legume) plants produced higher levels of flavonoids, which led to an increase in the abundance of rhizobia (beneficial nitrogen-fixing bacteria) in the root microbiome.

You gain some and you lose some

Breeding can also affect the root exudate composition of plants. Hybrid plants, for example, have been found to have different root exudate compositions compared to their wild ancestors. A study by Koehler et al. (2015) found that compared to wild race sorghum (Sorghum bicolor), a hybrid sorghum had a different composition of root exudates, including higher levels of some sugars and amino acids and lower levels of other sugars and amino acids. This change in root exudates composition can influence the ability of the plant to recruit specific microorganisms for association. For example, a study comparing the root exudates of wild rice (Oryza rufipogon) and hybrid rice (Oryza sativa) found that the hybrid rice had lower levels of certain sugars and amino acids, which can make it less attractive to beneficial microbes such as mycorrhizal fungi.

In our quest for higher yields, inadvertly we have lost on key aspects 
of plant-microbe interaction and how that shapes up the food we eat!        

Root exudates could very well hold the key to food security.

Root exudates and plant microbe interaction could hold the key-
But can we fix what's broken?        

Root exudates plays a crucial role in plant-microbe interactions, and various factors such as stress, plant age, monoculture, and breeding can affect the composition of root exudates and the ability of plants to recruit specific microorganisms for the association. Further research is needed to understand the specific changes in sugars, amino acids, secondary metabolites and the microorganisms recruited by plants in different scenarios.