‘Recipe’ for determining right mix of probiotics for crops

Microbiologists from Utrecht University, Nanjing Agricultural University in China and the University of York in England have developed a method for composing the right mix of ‘probiotics’ for a specific crop. This protects the crops against pathogens in a natural manner, making other pesticides unnecessary. Each year, up to one third of the harvest of important crops such as potatoes, rice, tomatoes and grain is lost due to diseases. This new probiotics approach will contribute to sustainable food production. The results of their research were published in Nature Communications on 24 September.

Enriching the soil of greenhouses and cropland using beneficial bacteria, called ‘probiotics’, is a growing trend as an alternative for the use of pesticides. However, until recently scientists were unaware of the optimal bacteria community for use with a specific crop in a specific soil type. The research by the botanists from Nanjing, Utrecht and York now makes this a possibility. They proved the effectiveness of their method in an experiment with a tomato grower in China whose crop was affected by the Ralstonia solanacearum bacteria. The applied probiotics mix completely wiped out the bacteria infection. Ralstonia solanacearum cause devastating plant epidemics worldwide. It mainly occurs in tropical and subtropical area, but also regularly causes outbreaks in Europe. As the causative agent of brown rot it is there responsible for major damage to the potato harvest.

Working hand-in-hand

The basis for the right mix of probiotics is the composition of the soil bacteria community in the soil in which the crops are grown. All of the bacteria present are then categorised according to their roles in the soil community. Optimal mixes consist of bacteria consuming different resources. Together, these bacteria will eat up all nutrients around plant roots, outcompeting pathogens. “Based on this result, we can identify which bacteria support one another by working hand-in-hand to fight the disease, without competing with one another”, explains PhD Candidate Tianjie Yang from Nanjing Agricultural University and Utrecht University.

The ‘gut flora’ in plants

Plants naturally live in symbiosis with a large number of useful soil bacteria, which help them absorb nutrients and water. These ‘useful’ bacteria also form a shield against pathogenic soil organisms. “You can compare it to our gut flora”, explains project leader Dr. Alexandre Jousset from Utrecht University. “That is also a mix of a large number of useful bacteria that are essential for the proper absorption of nutrients and a healthy immune system.”

 Intensive agriculture

In intensive agriculture, however, many beneficial moulds and bacteria disappear from the soil, so crops cannot develop properly and become more susceptible to diseases. As a reaction to this effect, farmers use pesticides that are seldom environmentally friendly. Enriching the soil with useful bacteria - ‘probiotics’ - is a growing trend, but it could be made much more effective. The researchers are in negotiations with a company for the application of their method.

 Cooperation between Nanjing and Utrecht

This study is the result of a special partnership between Utrecht University and the Nanjing Agricultural University. The two universities have exchanged students, doctoral candidates and lecturers since 2013. PhD Candidate Tianjie Yang, one of the main authors of the study, will spend two years of her doctoral research in Nanjing and two years in Utrecht. The leader of the study, Dr. Alexandre Jousset, is a University Lecturer in Utrecht and a guest lecturer in Nanjing.

This study was financed in part by the Chinese Ministry of Agriculture and the Chinese Science Organisation.

Publication

Trophic network architecture of root-associated bacterial communities determines pathogen invasion and plant health
Zhong Wei*, Tianjie Yang*, Ville-Petri Friman, Yangchun Xu, Qirong Shen & Alexandre Jousset*
Nature Communications, 24 September 2015, DOI: 10.1038/ncomms9413

 * Collaboration by Nanjing Agricultural University/Utrecht University

 Future Food Utrecht

This study is part of the Future Food Utrecht programme, an interdisciplinary research focus from Utrecht University that aims to find new solutions for a sustainable and healthy food supply acceptable and accessible for the world population. We focus on finding solutions that arise from understanding the fundamental mechanisms, and integrate knowledge and ideas from the full range of food-related disciplines. Future Food Utrecht scientists include botanists, pharmaceutical scientists, social scientists, urban geographers, medical scientists, ethicists, economists and veterinary researchers.

More information about Future Food Utrecht.

Contact

Monica van der Garde, Press Spokesperson, Faculty of Science m.vandergarde@uu.nl, 06 13 66 14 38.