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Friend or Foe? A Look at the Microbes Living in Euphorbia Latex

Posted by Marc M. Baum | December 17, 2015

Things are not always as they seem – especially in the enigmatic and microscopic world of microbes living in extreme environments.

Scientists from the Oak Crest Institute of Science discovered that first-hand during their recent study of Euphorbia, a highly diverse plant group, which includes over 2,000 different annuals, biennials, perennials, as well as tress and shrubs. The plants share the feature of having a poisonous, milky, white latex-like sap, along with unusual and unique kind of floral structures.

Results of their study appear in the December 2015 issue of the prestigious American Journal of Botany, the flagship journal of the Botanical Society of America. Findings in the article, “Euphorbia Plant Latex Is Inhabited by Diverse Microbial Communities,” are so significant, that Editor-in-Chief, Dr. Pamela Diggle, selected the article for special recognition in the Highlights section of the journal.

Discoveries published by Oak Crest, in collaboration with researchers from The Huntington Library, Art Collections and Botanical Gardens and University of California, San Diego, dispel the premise that the antimicrobial properties and toxicity of Euphorbia plant latex make it a hostile environment to microbes.

According to Dr. Marc Baum, Oak Crest senior faculty, when specimens from Euphorbia spp. were propagated in tissue culture, microbial growth was observed routinely, raising the question whether the latex of this diverse plant genus can be a niche for polymicrobial communities. “Based on these observations, we suspected that the latex would contain a low diversity of microbes, but what we discovered was totally unexpected. Euphorbia latex was found to contain complex bacterial and fungal communities using culture-independent methods,” says Dr. Baum. “Many of the identified taxa are known plant endophytes, but have not been previously found in latex. The most commonly observed bacteria in the studied samples were from a family that is not typically associated with plants, let alone latex.”

These results suggest that Euphorbia plant latex, a putatively hostile antimicrobial environment, unexpectedly supports diverse bacterial and fungal communities. Dr. Baum explains that the ecological roles of these microorganisms and potential interactions with their host plants are unknown. “Further research is warranted and will give us a better idea of the significance of these findings,” he adds.