Can the legume-rhizobia symbiosis be improved

Thursday 10 October 2019, 1.00PM

Speaker(s): William Deakin, University of York

The group of bacteria known as rhizobia, in association with certain leguminous plants (peas & beans), are capable of reducing atmospheric nitrogen to ammonia which is then converted to nitrate-based compounds used by the plant for growth. The relationship is symbiotic with legumes providing rhizobia with nutrients. The initiation of the symbiotic interaction involves molecular signalling between the plant and rhizobia, leading to the formation of new root organelles - nodules, in which the rhizobia are housed. The process of nodulation involves rhizobia penetrating the plant root and for a successful symbiotic relationship, rhizobia are taken up by root cells.

Of all the rhizobia, one strain known as NGR234 possesses the ability to nodulate the largest number of legume genera. It is able to do this through the production/secretion of a variety of molecular signals that, depending upon the legume host, can facilitate nodulation or in some cases block it. In the first part of my talk I will describe the actions of some of these signals and how the signals could be manipulated to improve inefficient symbioses.

Nitrate isn’t the only nutrient required by legumes and a variety of other compounds must be absorbed from the soil. Two key nutrients, iron and phosphate derivatives are typically present in soil as insoluble compounds which plant roots cannot absorb. In the environment other bacteria, referred to as plant-growth-promoting, aid plants to assimilate phosphates and iron (as well as many other nutrients). The second part of my talk will introduce my project at York which is to create consortia of plant-growth-promoting bacteria, together with rhizobia to supply a variety of nutrients to plants. This “bio-fertilizer” (and possibly “bio-pesticide”) will be tested on Soybean, an economically important legume.

Location: Dianna Bowles Lecture Theatre B/K/018