The Research Topic, published in Frontiers in Plant Science & Frontiers in Microbiology, aims to cover all aspects of biotrophic plant-microbe interactions.
— By Tanya Petersen
In just over thirty years there may be almost 10-billion people on earth, 2.5-billion more than now.
This population growth makes the global food security challenge seem quite straightforward: the UN’s Food and Agriculture Organisation estimates that by 2050 food production will need to increase by around 70% in order to feed the world’s people.
But underneath these seemingly simple numbers are layers of complexity, as outlined by Sustainable Development Goal 2 to “End hunger, achieve food security and improved nutrition and promote sustainable agriculture”. This SDG recognizes the inter-linkages between so many of the critical factors that will help us to achieve food security – increased agricultural efficiency, empowering small farmers, ending rural poverty, tackling the impacts of climate change and a critical drive towards overall sustainable agriculture.
Now, a fascinating new collection of research is tackling another of the complex layers in the global food security challenge: understanding the relationships between plants and microbes and how microbes and fungal parasites fool plants’ immune systems, sometimes causing devastating crop failures.
Led by Dr Ralph Panstruga from the Aachen University in Germany and Dr Pietro Daniele Spanu from London’s Imperial College, more than 200 researchers contributed to 34 research articles investigating Biotrophic Plant-Microbe Interactions with the hope of helping to improve agriculture for the benefit of future generations. This research, says Dr Panstruga, “will help us to develop new and novel strategies to protect crops from microbial invaders, reduce crop losses and contribute to increased agricultural efficiency”.
It’s well known that animals and plants live closely with microbes. All plants are colonised on their surface above and below ground, as well as within their bodies, by bacteria and fungi. Some microbes appear to bring benefits, for example by providing greater access to soil nutrients or elements (such as nitrogen) that are abundant in the air but not readily available to plants: these are mutualistic symbionts. Others are at least potentially harmful and can have a negative impact on the plants’ life to a greater or lesser extent: these are considered pathogens.
When microbes coexist intimately with plants exchanging nutrients, but without causing the direct death of the hosts’ cells and tissues, the interactions are called biotrophic, as opposed to necrotrophic ones in which the microbes kill and feed of the remains. In between these two extremes lie the hemibiotrophic interactions, which are characterized by an initial biotrophic and a later necrotrophic phase. For plants, there is evidence that these associations are extremely ancient and have existed as long as the organisms themselves, and they are thought to have influenced evolution for hundreds of millions of years.
Plants have evolved highly complex molecular detection and defence systems to control microbial colonisation of all these types, and interacting microbes have had to adapt and develop equally complex avoidance and counter defence measures. Until now, agriculturalists have based their attempts to breed disease resistant crops on the existence of genetically determined plant immune mechanisms but the capacity of microbes to evolve rapidly and effectively to overcome these resistances have led to catastrophic epidemics that threaten our core food security.