How do lichens withstand desiccation?

Duke University
Durham, North Carolina
DOI: 10.18258/12505
Raised of $4,300 Goal
Funded on 2/15/19
Successfully Funded
  • $5,275
  • 122%
  • Funded
    on 2/15/19

About This Project

Lichens, symbioses between fungi and algae, survive levels of desiccation lethal to most organisms. We recently discovered that seemingly unnecessary extra DNA segments ("introns") present in the lichen DNA coding for ribosomes are central to the induction of desiccation resistance. We hypothesize that the slowdown in ribosome assembly caused by the introns triggers the expression of genes protective against desiccation damage. We plan to identify these protective genes through RNA sequencing.

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What is the context of this research?

All cells have ribosomes, molecular machines that build proteins. Ribosome assembly is sensitive to stresses like desiccation. So we asked if the many introns found in ribosomal DNA (rDNA) of lichen fungi affect their remarkable desiccation tolerance. Using CRISPR, we moved introns from a lichen fungus into the rDNA of yeast, a fungus with no rDNA introns. Yeast desiccation tolerance went up 1000-fold with introns. We think that introns are not causing the resistance directly, but their removal during ribosome assembly slows it down, which then causes activation of genes protecting the cell from desiccation damage. In the presence of rDNA introns such genes remain on, maintaining cells on constant alert even in absence of desiccation.

What is the significance of this project?

Drought is a major problem for land-based organisms. Land plants evolved roots and evaporation controls to counteract water loss, but prolonged drought can lead to death. Worldwide, drought affects 64% of the land area, is projected to increase due to climate change, and causes large food losses. Not surprisingly, drought stress in plants is intensely studied, but contributions from remote corners of biology could open novel possibilities. One such understudied corner is lichens and their remarkable ability to withstand complete desiccation. Since biological mechanisms are not compartmentalized, understanding drought defenses in lichens would not just answer a question in basic science, but might lead to new practical applications to protect crop plants from drought damage.

What are the goals of the project?

We hypothesize that lichen rDNA introns, by slowing ribosome assembly, trigger expression of genes protective against desiccation damage. Using yeast as model, our immediate goal is to identify such genes by comparing transcription in four yeast strains we constructed. Three have lichen introns inserted at two locations ("A" and "B") in the yeast rDNA: the first has an intron in A, the second an intron in B, the third has two introns, one in A and one in B. The fourth has no rDNA introns. RNA from each strain will be sequenced. Gene expression in the four strains (each in three replicates) will be analyzed bioinformatically. Subsequent goals are to validate the genes' protective functions in yeast and in lichens and eventually to apply the findings to plants if feasible.


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RNA sequencing is part of a core project already in progress, aimed at understanding the basis of lichen desiccation tolerance. The project has been supported intramurally through undergraduate research funds provided by Duke University, and RNA sequencing is the first step towards a more comprehensive and expensive molecular analysis.

Endorsed by

I am delighted to endorse this clever project! One of the most important events in Earth’s history was the conquest of land by plants 480 million years ago. How the earliest colonizers managed to survive on dry land without succumbing to dehydration is a major conundrum. Clues to how they managed might be provided by lichens––a symbiotic partnership between a fungus and an alga––which display remarkable drought tolerance. Maybe one day, we will be able to 'engineer' this capability into crop plants, making them more tolerant to water loss?
This project will address a critical knowledge gap in the field of desiccation resistance. Dr. Armaleo brings his unique expertise in lichen biology and genomics. Working together with a talented team of undergraduates, his project has the potential to determine the mechanisms of the extraordinary resistance of lichens to drying.
Lichens are unique organisms -- they represent a symbiotic relationship between a fungus and alga, yet are more than the sum of their parts! Lichens occupy some of driest habitats on earth so they could well provide novel clues about the mechanisms that help organisms survive extreme desiccation. This research team is qualified to conduct the research, with the added benefit that they will likely be able to involve developing undergraduate scientists who want to explore research careers in biology and ecology.

Project Timeline

The first milestone (1.5 months) requires optimizing growth, harvesting yeast and extracting RNA of the highest quality. The second milestone (1.5 months) depends on the turnaround time of the sequencing facility, which depends on how busy they are when we submit our RNA samples. The third milestone (2 months) depends on the availability of bioinformatics consultation and on the complexity of the sequence data.

Jan 16, 2019

Project Launched

Mar 15, 2019

Growth of strains and RNA extraction

Apr 30, 2019

Obtaining sequencing data

Jun 30, 2019

Initial bioinformatics analysis results

Dec 31, 2019

Publish results in a peer-reviewed journal

Meet the Team

Daniele Armaleo
Daniele Armaleo


Duke University, Department of Biology
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Lilly Chiou
Lilly Chiou

Daniele Armaleo

I came to Duke University from Italy as a graduate student and never left Duke, where I am now an Associate Professor of the Practice of Biology in the Biology Department and teach undergraduate lab courses in Molecular and Cell Biology. Although I worked with fungi most of my life, I came to love lichens late in my career, inspired by Chicita Culberson, a world-class lichen chemist working in the Biology Department. Together with many collaborators, we just completed the first comprehensive lichen genome project on both alga and fungus of the lichen Cladonia grayi, and this project on the function of lichen introns is the first test of an idea born of that genome analysis. A large component of my research is done by undergraduates, and I consider sparking their interest in research my main mission as a professor.

Project Backers

  • 95Backers
  • 122%Funded
  • $5,275Total Donations
  • $55.53Average Donation
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