Niche Shifts Facilitate Mycorrhizal Fungal Specialization in Burmannia

Mycoheterotrophic plants (MHPs) are achlorophyllous and obtain nutrients through parasitizing mycorrhizal fungi. MHPs evolved from autotrophic ancestors independently but show obvious convergent evolution in adaptation to their life mode, such as reduced vegetative growth and habitat changes from open grassland/shrub-land to dense moist forests, accompanied by specialized relationships with a phylogenetically narrower range of mycorrhizal fungal lineages . This still have much to learn about what ecological factors have driven the specialization of fungal associations in MHPs during the evolution of mycoheterotrophy.

Burmannia s.l. comprises fully mycoheterotrophic, partially mycoheterotrophic, and autotrophic species, providing a rare opportunity and excellent model system for understanding the interaction between MHPs and mycorrhizal fungi. In this study, through surveying the fungal diversities in several populations of different Burmannia species and their co-occurring plants, this research revealed the ecological drivers promoting the changing plant-fungi relationships along the evolution from autotrophy to mycoheterotrophy.

This research showed that the different fungal compositions among habitats likely provide the basis for the fungal partner changes of MHPs, while the turning to fungal communities having lower phylogenetic distances during the habitat transition from open grasslands to shaded forests may have resulted in the specialization of mycorrhizal associations in Burmannia MHPs. This research highlight that the differential fungal associations in autotrophic and mycoheterotrophic Burmannia species are influenced by the communities of grasslands and forests, rather than their mode of life. Overall, this study sheds light on the enigmatic tripartite relationships among MHPs, mycorrhizal fungi, and co-occurring plants, providing new insights into the evolution of MHPs driven by plant-fungi interactions.

This study titled “Not only transitions in nutritional modes but also niche shifts facilitate mycorrhizal fungal specialization in Burmannia” has been published online in Functional Ecology with ZHAO Zhongtao  as the first author and ZHANG Dianxiang as the corresponding author. This study was supported by the National Natural Science Foundation of China. The article is available at https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2435.14706.

Figure 1. Burmannia species with different trophic mode (Image by ZHAO et al)