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Biological Sciences Colloquium: Shashini Welmillage

November 18, 2022 @ 4:00 pm - 5:00 pm

Shashini Welmillage, current graduate student in the Department of Biological Studies at UWM, will present a talk about her work entitled, “Beyond the Crop Legumes: Mechanisms of symbiosis between Mimosa pudica and Paraburkholderia phymatum.”

The nitrogen-fixing symbiosis between legumes and rhizobia plays a vital role in agriculture and minimizes the negative impacts of N-fertilizer. Existing knowledge of the symbiotic mechanisms is based on papilionoid crop legumes and associated α-rhizobia. In contrast, very little is known about mechanisms of symbiosis between Caesalpinioid legumes and their β-rhizobia symbionts. It is crucial to extend research beyond crop legumes and their symbionts to obtain an enhanced
understanding of legume-rhizobia symbiosis. This research is focused on studying the interaction between the Mimosoid legume Mimosa pudica and the β-rhizobia Paraburkholderia phymatum in both laboratory and natural environments. Using 16S RNA analysis of bacterial diversity, we show that exogenously inoculated P. phymatum increased its population on plant root but not in the rhizosphere in non-sterile soils but did not require the well-studied type VI secretion system for
outcompeting existing microbiome. A mutant defective in Nod factor biosynthesis failed to nodulate M. pudica showing that Nod factor is required for nodulation similar to the α-rhizobia. Using random transposon mutagenesis, we identified a mutant strain that was delayed in nodulation and formed ineffective symbiosis. The mutant is likely affected in synthesis of polysaccharides important for bacterial envelope. These results will help in expanding our knowledge about this important symbiosis between plants and bacteria.

The presentation will begin at 4:00 PM in Lapham N101, preceded by an informal Q&A from 3:45 – 4:00 PM.

Details

Date:
November 18, 2022
Time:
4:00 pm - 5:00 pm
Event Category: