New papers and arrivals

We are welcoming Reena Debray, our newest graduate student, to the lab! Reena’s time in the lab is off to a great start as she seeks to quantify the impact of phages on plant resistance to pathogens. Stay tuned for some great science.

I am also happy to share two new papers from the lab:

1. Berg, M., & Koskella, B. (2018). Nutrient-and Dose-Dependent Microbiome-Mediated Protection against a Plant Pathogen. Current Biology, 28(15), 2487-2492.

During her final year of graduate school, Maureen Berg spent time in our lab to learn about plant microbiomes (to complement her amazing work on gut microbiota of C. elegans, as can be seen here: https://www.nature.com/articles/ismej2015253). Maureen and I set out to ask a very simple question: does the tomato phyllosphere protect against pathogen colonization. We used a new method we’ve been developing in the lab, where we transplant the microbiomes from field-grown tomato plants onto mostly sterile plants in the growth chamber. In this way, we can control host genotype, and other extrinsic factors, and examine how plants with these augmented microbiomes differ in phenotype from those without. Of course we had to add a twist, and in this case we thought we would ask how dose impacts microbiome-mediated protection. To make a long story short, the answer is that it does! But not always in the way we would have predicted – sometimes less was better. We then tested these patterns more explicitly using a constructed community of 12 culturable isolates from the tomato phyllosphere, and were able to confirm this counterintuitive result – which we are now following up on. Moreover, we accidentally discovered that fertilizing the plants before the experiment abolished the previously observed protection – a result we confirmed with a fully factorial experiment. When the plants were not fertilized, pathogen colonization depended critically on whether the phyllosphere had been colonized by commensal bacteria, but when they were fertilized, the phyllosphere no longer had any observable protective effects. See news coverage of the work here: http://news.berkeley.edu/2018/07/26/fertilizer-destroys-plant-microbiomes-ability-to-protect-against-disease/

2. Koskella, B., & Taylor, T. B. (2018). Multifaceted Impacts of Bacteriophages in the Plant Microbiome. Annual review of phytopathology, 56, 361-380.

In collaboration with Tiffany Taylor at Bath University, we spent some time thinking about the myriad ways in which phages might impact the plant microbiome. This blossoming field nicely complements work from the human microbiome (and other systems) suggesting that phages are key components of the microbiome, shaping composition, diversity, and function. This means there is plenty of work to be done in order to determine how and when such knowledge can be leveraged in human health and agriculture.