Agricultural production systems worldwide are facing many challenges and must adopt more dynamic, efficient and sustainable production methods for increasing food and fodder production to feed a growing population with fewer resources (FAO). Firstly, the world population is predicted to reach roughly 10 billion by 2050 (http://esa. un.org/wpp/). Secondly, urbanisation reduces available agricultural land, both by encroachment and by increasing pollution and water demand in adjacent areas. Thirdly, economic growth and social development are increasing demand for meat-based diets and fodder, rather than food crops, whilst simultaneously increasing greenhouse gas emissions.
Climate change is a challenge also for sustainable plant disease control. In particular, emerging pathogens (and pests) find favourable conditions in new regions. Meanwhile, the increased unpredictability of the weather is leading to an increase in, and unpredictability of, abiotic stresses, such as drought, heat and cold, thereby altering risk patterns for specific diseases. This leads to the need to understand the subtle interactions between these abiotic stress factors, the hormones regulating the ability of the plant to adapt to abiotic stress, and microorganisms exhibiting different lifestyles. These range from mutualistic mycorrhizal fungi and rhizobia over beneficial endophytes to harmful pathogens. There are also examples where the same microbe can act as a benign of beneficial endophyte under some conditions and as a disease-inducing pathogen under others. While plant diseases can devastate crops, they can often be controlled by cultural practice, disease resistance, biological control and the use of pesticides. BestPass was a major initiative aimed to deliver new insights into the nature of the relationships between plants and associated microorganisms – both beneficial and pathogenic, and by both biological control and stimulation of host growth.
The world needs to increase crop yield while reducing pesticides and the use of inorganic fertilisers- in order to meet the challenges of population growth and climate change. Plant endophytic microorganisms can improve plant yield and enhance plant tolerance to abiotic stress as well as to pathogens under experimental conditions, but these effects are often not sufficiently stable for practical application. The knowledge obtained from studying the impact of endophytes on plant health is expected to benefit the sustainable development of agriculture over the coming decades. Examples of new knowledge gained through the project used model organisms such as Serendipita (syn. Piriformospora) indica, arbuscular mycorrhiza (AM) fungi and novel bacterial and fungal endophytes, as well as three way interactions involving beneficial fungi, bacteria and host plants. The availability of genome sequences of the interacting partners is an important prerequisite for gaining knowledge about these three way interactions and their use in sustainable plant production systems and meeting the challenges of climate change and modern societies.
