Source: National University of Singapore (NUS)

This exciting discovery holds great promise for sustainable food security across diverse soils and crops.

Scientists from the Singapore Centre for Environmental Life Sciences Engineering (SCELSE) and the National University of Singapore (NUS) uncovered one of nature’s most potent tools in an arsenal to combat today’s agricultural challenges: agro-microbials – or agro-chemicals of natural origin – that can enhance the synergy between crops and microbes, and ultimately improve crop yield and productivity.

In a study conducted over five years from 2018, the scientists discovered that a well-known protective hormone typically released by plants above ground during periods of stress – a volatile organic compound (VOC) known as methyl jasmonate (MeJA) – possessed a hitherto unknown function. They found that MeJa serves as a shared, possibly secret, language that allows the plant to communicate with the surrounding multitude of microorganisms embedded in the soil.

The research team made three important discoveries:

1. Using a specially engineered airflow system, scientists have found, for the first time, that MeJA is released underground by the plant roots in a volatile form.

2. The presence of volatile MeJA triggers and enhances the formation of beneficial biofilms, microbes attached to surfaces, in bacteria situated at a distance from the plant roots thereby extending the region of plant influence by 1,000 times and uncovering a greater role of plants in soil health and primary productivity on terrestrial Earth.

 3. These bacteria in the biofilm release a different set of volatile compounds that can boost plant growth by up to 30% thereby generating a 2-way communication between plants and microbes.

The findings were detailed in the scientific paper titled ‘Volatile methyl jasmonate from roots signals the formation of host-beneficial biofilms by the soil microbiome’, which was published in the prestigious journal Nature Chemical Biology on 13 November 2023.

Associate Professor Sanjay Swarup, who is Deputy Research Director at SCELSE and Principal Investigator at the Research Centre on Sustainable Urban Farming (SUrF) under NUS Faculty of Science, said, “The impact of this discovery is manifold and key to sustainable agriculture. Harnessing these agricultural microbes will not only boost crop productivity, but using nature-based agrochemicals, also reduce the need for synthetic inputs and mitigate the environmental impact of modern farming practices.”

Having discovered nature’s own way of communication between plants and beneficial microbes, the research team has filed a patent for novel application of this natural chemical signal and the beneficial bacteria it stimulates, to improve the resilience and productivity of agricultural systems. The upshot of this could be a new generation of agro-chemicals or nature-structured chemicals and biological solutions, which can be used to enhance the benefits for plants.

Agro-microbials Can Influence Plant Growth And Address Food Security

As the world population is projected to reach 10 billion by 2050, ensuring food security for its inhabitants has become one of the most pressing challenges of this century. Singapore, for example, has set a “30 by 30” goal – to be able to produce 30 per cent of our nutritional needs by 2030.

To achieve these goals, agricultural productivity must urgently grapple with the effects of climate change, land degradation, and increasingly unpredictable weather events. Agro-microbials – and nature-based agrochemicals – are now emerging as a promising strategy for sustainable agriculture.

Agro-microbials encompass microbial communities associated with crops, and they serve critical functions of plant growth promotion, disease prevention, and nitrogen fixation. They also help to keep the soil fertile by breaking down organic matter, recycling nutrients, and creating humus to retain moisture. Diverse communities of agro-microbials can be found inside biofilms, where they are embedded in a self-produced matrix.

The ‘ Fragrance’ Emitted By Plant Roots Causes A Positive, Cascading Effect

Fragrant MeJA VOC can impact microbes from a distance. This highlights the fact that the volatile signal can extend the influence of plant roots beyond their immediate zone  called rhizosphere (a region of two millimetres from roots, where soluble and volatile molecules facilitate the communication between plants and the associated microbiota). Zone of plant influence could be 1,000 greater than previously thought.

The paper’s joint first author, Dr. Omkar Kulkarni, who is now a research scientist at L’Oréal-SCELSE joint laboratory, said, “Plants can’t talk like us, but they have their elegant ways of conversing over long distances. This exciting discovery will not only bring fundamental insights about plant-microbe interactions but also potentially pave the way for nature-based agrochemicals.” Dr Kulkarni conducted this research as part of his PhD work at the Department of Biological Sciences of the NUS Faculty of Science.

Dr. Mrinmoy Mazumder, an NUS research fellow at SCELSE and joint first author of the paper, added, “VOC-mediated communication between plants and microbes in the rhizosphere spans the distance, orchestrating nature’s harmonious collaboration. This discovery holds fundamental and translational significance for the scientific community, offering opportunities to delve into mechanistic insights and develop tailored solutions for stress management in diverse crop varieties.”

This research was funded by SCELSE and supported by NUS. A detailed explanatory video, “SCELSE-NUS scientists uncover plant hormone that recruits good bacteria to boost plant growth by 30%” can be found on SCELSE’s YouTube.

Future Plans

As a follow-up from the initial findings, the team will further investigate the exact chemical nature of the compounds released by the soil microbial environment that stimulates plant growth. The team will also design an ecology-inspired microbial community and nature-based agrochemicals to harness the new discovery of how plants enlist the help of beneficial soil microbes to trigger plant growth.