Plant resistance inducers (PRIs): perspectives for future disease management in the field

Plants are confronted with numerous biotic stresses that may affect productivity. Besides their constitutive defence, plants can activate specific metabolic processes to enhance resistance upon stress detection. These defence mechanisms can also be activated through the recognition of plant resistance inducers (PRIs). This review highlights some of the current challenges that prevent the adoption of PRIs in agriculture, and explore research topics and knowledge gaps to be addressed for bringing PRIs closer to practice. First, we present studies on the variance of induced defence responses and examine the possibility of employing inducibility in breeding strategies as well as the possible role of epigenetics. We also discuss the efficiency of PRIs in future climate and knowledge gaps on this subject. Remote sensing, high-throughput phenotyping and modelling in combination with PRIs as part of decision support systems and integrated pest management are further possibilities to advance the use of PRIs. Finally, we discuss the challenges which need to be addressed to make PRIs available for small-scale farmers in low-income countries. Although PRIs have successfully presented significant rates of disease prevention under controlled conditions, converting these findings into field application still depends on more studies, e.g. on how they can be integrated into disease management programmes. Better mechanistic understanding of IR together with the coupling of PRIs to new disease monitoring and protection strategies can give PRIs a stronger role in future agricultural practice.