Identifying transcriptomic indicators of growth rate and environmental stress in marine phytoplankton

Marine phytoplankton are an extremely diverse group of organisms that perform about half the photosynthesis on Earth and play a key role in the carbon cycle. Climate warming is expected have dramatic effects on environmental conditions that influence both the productivity and taxonomic composition of marine phytoplankton communities. The diversity and complex evolutionary history of the phytoplankton presents challenges for modelers who seek to project changes to phytoplankton productivity and biogeography and subsequent impacts on biogeochemistry in response to climate warming. Thousands of plankton species are routinely grouped into a few functional types, that are distinguished by a small number of ecological and physiological traits that that are poorly constrained by data. Transcriptomics can be used to monitor gene expression of phytoplankton communities in situ and provide us with a much more mechanistic understanding of how and why different phytoplankton species and/or functional groups respond to changing environmental conditions. Here we propose to identify differentially expressed genes associated with growth rate and with acclimation to several environmental conditions under different time-scales from transient application of a new environmental condition to multi-generation acclimation, across several ecologically important marine phytoplankton taxa in controlled lab cultures. This work will allow us to identify universal transcriptomic signals associated with phytoplankton growth rate and acclimation to environmental conditions, and will provide the beginnings of a database that can be used to interpret the increasing number of marine phytoplankton metatranscriptomes taken from the field, and facilitate the identification of the genetic bases of key traits that define phytoplankton functional groups for next-generation biogeochemical models.