PIPages
Labs

Liana Burghardt

Pennsylvania State University, PA·Ecology & Evolution·Early-career

In mutualisms, two species both benefit from living together. Evolutionary theory predicts that such partnerships should shrink the genetic diversity of both partners.

Fields

Ecology & Evolution

Plant Science & Agriculture

Microbiology & Immunology

Topics

mutualism

symbiosis

host-microbe interactions

Grants
2 known grants, through May 2031

What they work on

  1. Identify which legume host traits support which rhizobial bacteria by analyzing plant characteristics and field samples from legumes, using traditional and AI-enabled image and statistical analysis.
  2. Test whether living alongside particular legume hosts maintains bacterial genetic diversity, using multigenerational greenhouse experiments and AI-based simulations of bacterial evolution.
  3. Characterize the function of Sinorhizobium meliloti genes that affect bacterial fitness inside Medicago truncatula hosts and infer selection on them, using whole-genome sequencing of competing strains and field allele frequencies.
  4. Examine how adaptation to soil interacts with adaptation to hosts, and identify the selection and reward mechanisms that keep the legume-rhizobia mutualism stable.

More about the research

Yet bacteria that can live either with or without a host often stay highly diverse. The lab studies this puzzle in one of the most important plant-bacteria partnerships. Legumes, such as clover and beans, host rhizobia, soil bacteria that live inside small root swellings called nodules. Inside the nodules, the bacteria convert nitrogen from the air into a form the plant can use, and the plant feeds them sugars. Because the bacteria spend much of their lives in soil and must find a new host each plant generation, they face selection both inside and outside hosts. Two projects ask how hosts, soil and evolution together shape these beneficial bacteria.

Why it matters

Nitrogen-fixing bacteria are key to eco-friendly farming and to nutrient cycling. Knowing which host plants and genes keep beneficial strains diverse and effective could help farmers and restoration projects choose better legume-bacteria pairings. It could also help predict whether bacteria will specialize on hosts or remain beneficial. More broadly, the work could improve how beneficial microbes are used to support host health in other systems.

Known grants

From NIH and NSF research grants. Labs often have other funding we can't see.

CAREER: Unearthing impacts of leguminous plant co-occurrence on genetic diversity of bacterial mutualists

NSF · Jun 2026 – May 2031

Evolving together, evolving apart: probing the genomic basis of a facultative host-microbe mutualism

NIH · Mar 2026 – Feb 2031

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The school

Pennsylvania State University: 60 labs on PI Pages, $1.3B a year on research, 743 research doctorates a year.

More about Pennsylvania State University

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