Back to the future: Using herbarium specimens to isolate nodule-associated bacteria.

Area of Science:

• Microbiology
• Botany
• Evolutionary Biology

Background:

• Herbarium specimens are valuable resources for studying plant ecology and evolution.
• Current research primarily uses specimens for genetic material via culture-independent methods.

Purpose of the Study:

• To demonstrate the feasibility of culturing nodule-associated bacteria from herbarium specimens.
• To explore plant-microbe interactions at novel spatiotemporal scales using historic samples.

Main Methods:

• Historic and contemporary nodules from Medicago lupulina were used to establish a culture collection.
• Bacteria were isolated and identified from specimens collected in 1950, 2004, and 2015.

Main Results:

• Historic bacteria from 15 genera were successfully recovered from herbarium specimens.
• This is the first study to isolate historic bacteria from herbarium samples.
• While the primary symbiont Ensifer was not recovered, other potential nodulating and growth-promoting bacteria were identified.

Conclusions:

• Herbarium specimens offer a viable method for culturing historic bacteria, expanding research possibilities for plant-microbe interactions.
• Future studies should involve inoculating plants with historic strains to assess nodulation, plant phenotype, and fitness.