Nutrient assimilation and exchange in lichen mutualisms

Lichen are classic examples of mutualisms where a fungal host (mycobiont) and an algal symbiont (photobiont) partner with each other in order to thrive in harsh and limiting conditions. This relationship has long been hypothesized to be predominantly nutritional and it has been demonstrated that the photobiont provides the mycobiont with an abundant source of carbon through photosynthesis. However, the other nutritional dynamics between the two partners are poorly understood in large part due to the difficulty in physically separating them. 

We developed a novel method to isolate sufficient mycobiont and photobiont tissue for stable isotope analysis of each component of the lichen holobiont. Our lab is using this new technique to ask and answer diverse questions about the trophic niches of lichens, including how trophic strategy varies across species and conditions, such as elevation. Further, we are combining this separation technique with stable isotope tracers to trace the pathway of nutrients into and within lichen holobionts. This work will provide new insight into how these relationships function and the tradeoffs involved in maintaining symbiotic partnerships.

These projects were funded by a National Science Foundation Postdoctoral Research Fellowship in Biology (Award #2109909) and a Faculty Research Grant from Lingnan University (105127).