Back to the future: Using herbarium specimens to isolate nodule
associated bacteria
Abstract
Herbarium specimens are increasingly being used as sources of
information to understand the ecology and evolution of plants and their
associated microbes. Most studies have used specimens as a source of
genetic material using culture independent approaches. We demonstrate
that herbarium specimens can also be used to culture nodule-associated
bacteria, opening the possibility of using specimens to understand
plant-microbe interactions at new spatiotemporal scales. We used
historic and contemporary nodules of a common legume, Medicago lupulina,
to create a culture collection. We were able to recover historic
bacteria in 15 genera from three specimens (collected in 1950, 2004, and
2015). This work is the first of its kind to isolate historic bacteria
from herbarium specimens. Future work should include inoculating plants
with historic strains to see if they produce nodules and if they affect
plant phenotype and fitness. Although we were unable to recover any
Ensifer, the main symbiont of Medicago lupulina, we recovered some other
potential nodulating species, as well as many putative growth-promoting
bacteria.