Rice is the most important staple food on the planet, with more than half of the world’s population feeding mainly on its small grains.
Like all organisms, rice plants are struggling with the effects of climate change. More heat and less rainfall are affecting the most common varieties. In view of its importance for feeding billions of people, this poses an enormous risk.
In an international joint project, researchers from the US, the UK and Germany want to make rice plants more resistant to the threat of climate change. Arthur Korte, bioinformatician at Julius-Maximilians-Universität Würzburg (JMU), is playing a key role in the project.
For him, the international project offers an opportunity to apply his research to what is probably the most important crop plant in the world.
The transnational cooperation was a prerequisite for the funding application. In addition to Korte, project leader Julie Gray (University of Sheffield, UK), and Sally Assmann (Penn State University, US), a fourth partner is also on board: the International Rice Research Institute (IRRI) in the Philippines.
“IRRI is the leading institution when it comes to rice. They have the expertise, all the rice varieties and, of course, the cultivation areas to implement the project,” Korte said.
Two-hundred-year-old rice landraces are cultivated in the Philippines, both under regular conditions and under so-called rain shelters:
“You can imagine them like a big tent. It gets even warmer under these, and the plants get less water. We are therefore creating a possible future climate scenario,” Korte explained.
In Sheffield, the same setup will also be recreated on a smaller scale in plant breeding chambers.
The start date was February 1, and after four to six weeks, the researchers want to take the first samples and extract RNA in the Philippines.
“Stress factors such as heat and drought have a serious impact on the plant’s subsequent yield even at an early stage of growth,” Korte said.
Genetics
To achieve a stable yield despite changing climatic conditions, the team wants to get to the bottom of the rice plants’ genes. A particular focus is on stomata, also known as guard cells. These tiny pores on the undersides of all plant leaves are responsible for gas exchange. They absorb carbon dioxide (CO2) and release oxygen. During this process, the plants also lose water in the form of water vapour.
Based on several years of preliminary work, Gray and Assmann assume that genes that regulate these processes have enormous effects on the yield of plants – which makes them target genes for the project.
The researchers are looking for alleles, natural variants of these genes. Such small mutations occur repeatedly over thousands of years. Many have no significant effects, and the mutations with negative effects are sorted by evolution. The researchers are interested in those rare examples “that ensure that individual proteins work a little more actively and better – in our case for greater resistance to heat and drought,” Korte said.
Crossbreeding
Once these promising gene variants have been identified, IRRI comes into play again. Crossbreeding programs are used to transfer the desirable traits to common rice varieties.
“As with all crops, there are certain elite breeds of rice. These have been bred over hundreds of years because they promise the highest yield. However, these varieties are often particularly susceptible to stress factors such as heat and drought,” Korte said.
With around 30,000 genes per rice plant and various variables, enormous amounts of data are quickly generated and machine learning models will analyze them. Korte wants to predict which gene expressions could ultimately lead to higher yields under more difficult conditions.
“Here in Würzburg, with the Center for Computational and Theoretical Biology (CCTB) and the new Julia 2 mainframe computer, we have the necessary infrastructure and computing power to implement such models.”
Support from schools
In the US and the UK, pupils will also contribute to the project. The basis for this is a database with climate variables, i.e. different temperature values or amounts of precipitation, for all 200 original rice varieties. A map puts these in relation to different alleles. If a student discovers, for example, that plants with a certain allele often occur in regions with higher average temperatures, they provide the researchers with a hypothesis.
“We then get feedback on this and can check in the lab whether there really is a connection. I think this is a great way of making our research accessible and sharing it with the public,” said Korte.
Funding for the €2.5m project is provided by the German Research Foundation (DFG) together with the British Biotechnology and Biological Sciences Research Council (BBSRC), the US Department of Agriculture (USDA) and the National Institute of Health (NIH).