Plants and microbes continually interact, both for roots in the soil and shoots above the ground. These interactions can be either beneficial or pathogenic and can have tremendous environmental/ecological and agricultural implications. Beneficial microbes can enter into a symbiotic relationship with their host plant, providing them with essential nutrients in exchange for carbohydrates from the host. Examples of symbioses include rhizobia bacteria and mycorrhizal fungi. By contrast, pathogenic microbes can damage, and even kill, their host plant, and include an array of bacteria, fungi and viruses.
Due to the immense economic importance of plant diseases and symbioses, considerable research efforts have focused on advancing the understanding of many plant-microbe interactions. Researchers have studied these intricate relationships from the entire ecosystem to the individual molecular and genetic components. Indeed, establishing the mechanisms that promote symbioses or enhance disease resistance requires expertise ranging from plant and microbe biology, to ecology, soil biology, cellular biology, molecular biology, biochemistry, plant nutrition/physiology, bioinformatics, genomics and genetics. Enhancing this knowledgebase could help to underpin future strategies aimed at controlling and/or optimising critical plant-microbe relationships, both in natural communities and in major crop species and production systems.
Images of various legume roots colonised by compatible rhizobia bacteria. This symbiotic interaction results in the formation of novel organs that form on the host roots, called nodules, which act to house the rhizobia. Inside the nodule, the rhizobia fix atmospheric di-nitrogen for their host plant in exchange for carbohydrates. Photos courtesy of Dr Brett Ferguson (CILR, UQ, Australia).
The root of a Brassica napus plant infected by the fungal pathogen Leptosphaeria maculans. Commonly referred to as black-leg disease, this interaction is responsible for considerable yield losses each year. Photo courtesy of Dr Annaliese Mason (CILR, UQ, Australia).
(by Dr Brett Ferguson)