Rooting Quercus dumosa shoots in vitro and investigating the possible use of native mycorrhizal fungi to improve growth

Quercus dumosa, or the coastal sage scrub oak, faces numerous threats to its native range, such as fires, urban development, and climate change. Unfortunately, Q. dumosa’s acorns cannot survive the dry conditions required for seed banking, and living collections require considerable space. One alternative for ex situ conservation is tissue culture, in which microplants from many individuals can be maintained in a small space and away from environmental threats. Many Q. dumosa can now be cultivated in vitro relatively easily, but those shoots must be induced to form adventitious roots to create a whole tree. Like many other oak species, rooting Q. dumosa plants is difficult and often inconsistent. However, the concentration of auxin and the duration at which it is applied show clear effects on microshoots, regardless of genotype. These results, as well as those of experiments which did not succeed in improving rooting, suggest that rhizogenesis in Q. dumosa is a complex problem. To improve the chances of rooted plants surviving the transition from lab to field conditions, they were then exposed to native mycorrhizae cultures harvested from wild mushrooms. Several rooted plants showed clear signs of successful colonization in vitro, meaning that next step is to evaluate how well they adapt compared to those plants without mycorrhizal.