New strategies to combat root rot

In his doctoral thesis, agricultural scientist Wilken Boie is researching the prevalence of certain species of fungus in arable soils and the potential for improving the soil microbiome in the interest of plant health.

The aim of the doctoral researcher at the Institute of Phytopathology at the Faculty of Agricultural and Nutritional Sciences is ambitious: through his research, Wilken Boie wants to help reduce the use of fertilisers and pesticides on arable land in future or even make it completely unnecessary in some instances. "But we have a really long way to go before that can happen," explained the 25 year old from Alveslohe near Henstedt-Ulzburg who worked at various farms while studying at Kiel University. His interest in "applied biology" was kindled by his parents: his mother teaches agriculture at a vocational school, his father works at the German Farmers’ Association. Boie specialised in phythopathology because he was particularly captivated by his Bachelor's degree lectures on plant diseases and plant breeding. "Phythopathology deals with issues of plant breeding, like how plants can be made resistant to certain diseases." He is also fascinated by microbiome research. This research is still in its early stages, though.

Experts define the microbiome as the totality of all the micro-organisms in a certain habitat, for instance, in arable soil. Some of these tiny life forms are damaging to plants, others protect them from diseases and pests or are important for growth. "We still do not know very much about the complex interplay between micro-organisms in the soil and in plants. We know that the organisms all interact. I want to find out whether there are certain connections in the microbiome that counteract root rot," said Boie, who means "billions" of micro-organisms when he talks about the "totality of micro-organisms". This is why it makes sense for him to limit himself to a few species, he said.

In this case he is focusing on the Pythium fungus that causes plant diseases. This genus is made up of more 200 species. "Pythium ultimum and Pythium silvaticum, which I am looking at in closer detail, are present in all soils." They attack roots and damage cereal crops as well as sugar beets, sweetcorn, tomatoes, cucumbers and many other crop plants. The root rot caused by Phytium fungus makes it harder for the plants to absorb water and nutrients. The plants do not thrive or grow at all, and their stems bend and buckle.

"Farmers see the result in their fields and try to fix the symptoms using fertilisers, pesticides or irrigation." Microbiome researcher Boie gets to the roots of the problem in his doctoral thesis (his doctoral degree supervisors are Professor Daguang Cai and Professor Joseph-Alexander Verreet). "I am looking at whether the type of soil – i.e. the texture and moisture – affects the fungus and how this fungus interacts with other micro-organisms. If there are connections – and, from the current standpoint, there seem to be – we could promote plant health through targeted changes to the microbiome." This is Boie’s hypothesis, which he has been investigating since 2019 with the assistance of farmers from the EU and Switzerland. Over a period of three years he collected soil samples from 45 different sites as well as extensive information on climate, weather, location, fertilisation, usual plant diseases.

"The next steps now are to analyse and evaluate the samples," said Boie. For the analysis, he has decoded the genetic material of the micro-organisms in the soil samples, specifically the genetic material of fungus in general, of Pythium fungus in particular and of various bacteria. Now follows the evaluation of this extremely extensive data collection as the basis for further research. For this purpose, the agricultural scientist is currently working with the support of his colleague Markus Schemmel on creating computer software with algorithms designed to highlight connections between micro-organisms. Boie’s evaluation work is also supported by experts at Zhejiang University in Hangzhou, China. During a research stay there, likely to take place in 2022, he will further analyse the complex data in cooperation with scientists at the Department of Bioinformatics. A scholarship from the Heinz Wüstenberg Foundation is enabling Boie to go on this study trip.

Author: Jennifer Ruske