Ecological Genetics of Plant-Bacteria Association : lessons from serpentinophytes and legumes

Prof. Alessio Mengoni, University of Florence, Italy

Similarly to the animal body, a diverse range of bacteria, including pathogens, mutualists, and commensals are supported by plants. These bacteria grow in and around roots, in the vasculature, and in the aerial tissues and are known as rhizospheric, endophytic and phyllospheric. Of these, rhizospheric and endophytic bacteria have been widely studied for their plant-growth promotion abilities, but several basic questions on their ecological roles are still unanswered. We have focused our curiosity on two plant species, Alyssum bertolonii, a nickel-hyperaccumulating endemic serpentinophyte, and Medicago sativa (alfalfa), one of the most diffused forage legume crops. A. bertolonii is intriguing for its peculiar habitat (serpentine soil) and the toxicity due to the heavy-metal Ni, while the legume alfalfa is interesting since the symbiotic interaction which takes place with nitrogen-fixing rhizobia. These two plant species allowed to shed some light on the ecological meaning of “being plant-associated” and on the many different genomic recipes of bacteria for colonizing a plant. Recent results coming from molecular ecology studies, genome sequencing and computational biology analyses will be discussed.