Host variation for interactions with beneficial plant-associated microbes

Beneficial plant-associated microbes can profoundly influence plant health by suppressing disease, enhancing nutrient uptake, fixing atmospheric nitro gen, and promoting plant growth. Host variation, among cultivars or plant g enotypes, for response to beneficial microorganisms suggests that plant gen es play a role in supporting these interactions. Such host variation can be found among diverse groups of microorganisms including rhizobia, mycorrhiz al fungi, and microbial biocontrol agents. Discrete variation among plant g enotypes for interaction with beneficial microbes has led to the discovery of single genes that specify compatible interactions. Continuous variation for interaction phenotypes such as disease suppression, plant growth, or nu trient uptake have led to hypotheses, and in some cases genetic description s, of multigenic control of these interactions. Future research into the ro le of plant genes involved in hosting beneficial plant-associated microbes will provide greater insight into this relatively unexplored area of biolog y and should provide new tools to improve plant health in agriculture.