White pine blister rust's habitat range is changing with the climate

New study in Sequoia and Kings Canyon National Parks demonstrates the complexity of changing plant-pathogen interactions

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a yellow fungus infecting the branch of a white pine tree

Marek Argent on Wikimedia Commons (CC BY-SA 3.0) 

A rapidly changing climate is expected to shift where species live. This will also alter human activities like agriculture and forest conservation, as the ranges of plant pathogens change. 

Scientists have been predicted that climate change will both increase and decrease the prevalence of a pathogen across its geographic range, depending on local climate effects, a pathogen’s favored conditions, and host factors. In an article published in Nature Communications, a group of researchers led by Joan Dudney demonstrate exactly this in a natural system. 

The researchers report the effects of climate change on the occurrence of white pine blister rust in the Sequoia and Kings Canyon National Parks (SEKI) in California. Blister rust is a fungal disease that threatens white pine forests across Europe and North America. Leveraging blister rust prevalence data from two surveys conducted twenty years apart (1996 and 2016) in SEKI, alongside climate data over the same timeframe, they authors found that a warming, increasingly dry climate caused contraction of blister rust's range at low elevations and expansion at higher elevations, where conditions remained relatively mild. They noted an approximately 33 percent decline in overall disease prevalence despite these expansions and high elevations.

The blister rust fungus has a complex lifecycle that requires both a white pine tree and an alternative host, such as Ribes shrubs. Dudney and her fellow researchers found that alternative hosts were less common at higher elevations, likely limiting blister rust's ability to infect pine trees at those elevations even though the pathogen could live there. They also observed that aridity, or dryness, played an important role in determining infection risk.

The study provides a roadmap for future studies on host-pathogen-climate interactions. Genomic adaptations of rapidly reproducing pathogens to changing conditions could further alter these dynamics and represent an additional avenue to explore in future work.