Faculty Advisor

Kirkpatrick, Betsy

Area of Study

Science and Mathematics

Publication Date

Summer 2011


Scotch broom (Cystis scoparius) is invading the South Puget lowlands, presumably with help from the nitrogen-fixing symbiotic bacteria that are found in its root nodules. With this nitrogen source, Scotch broom is not limited by low nitrogen levels in the soils like many other plants. The goals of our research are 1) to identify the nodulating bacteria of Scotch broom in the Northwest, British Columbia, and Canberra, Australia to explore the diversity of Scotch broom symbionts and 2) to explore the possibility of multiple occupancy in Scotch broom nodules. Using 16s rRNA sequencing, we will identify the bacteria of Scotch broom nodules from Washington, British Columbia, and Canberra, Australia. We recently identified the South Puget Sound lowland prairie Scotch broom symbionts as predominantly from two genera: Burkholderia and Rhizobium (British Columbia and Australian sequence data to follow). Moreover, there were two nodules of the ten from which both Burkholderia and Rhizobium were successfully isolated and sequenced. Therefore, it is possible that multiple bacterial species can live within a single Scotch broom nodule. Neither the presence of Burkholderia nor multiple nodule occupation has been previously well-documented in a temperate zone legume and a survey of Scotch broom symbionts of the Northwest, USA has not been performed.


University of Puget Sound