INVESTIGATORS: Todd Mockler (PI), Todd Michael, Douglas Bryant, Malia Gehan
INSTITUTIONS: Donald Danforth Plant Science Center, St. Louis, MO; Ibis Biosciences, Carlsbad, CA
PROJECT SUMMARY: The goal of this Brachypodium ENCODE (Encyclopedia Of DNA Elements) project is to identify and characterize all of the functional elements associated with progressive drought response in the Brachypodium distachyon genome sequence, and to develop integrated genome feature maps that will enable advanced modeling of complex pathways in plants. Brachypodium is a model organism for grasses, including potential bioenergy feedstocks, and this effort will develop deep knowledge of chromatin dynamics and gene networks related to abiotic stress responses in these plant species. This knowledge is necessary for the improvement of bioenergy grasses, which is needed for economical production of cellulosic biofuels in the US. To accomplish this goal, this Brachypodium ENCODE project will: (1) obtain fundamental information about Brachypodium’s transcriptome, epigenome, chromatin dynamics, and gene regulatory networks; and (2) elucidate the regulatory dynamics of gene networks that can be manipulated to increase energy grass crop productivity.
Physiological analysis will be coupled with drought-focused genomic and transcriptomic profiling in Brachypodium. These assays will include daily measurements of photosynthetic efficiency and membrane damage during drought stress. Drought-treated plants with physiological symptoms of stress will be re-watered, allowed to recover, and then reassessed to determine if they are capable of revival. Periodic sampling of tissue for ‘omics assays will be conducted from just before signs of physiological stress occur until plants can no longer recover with re-watering. Sampling will be conducted at several intervals to ensure that circadian/diel regulation does not confound downstream analysis and interpretation. To capture dynamic genomic features responding to progressive drought, multiple types of whole-genome analysis will be performed including mRNA and small RNA transcriptome profiling, DNA methylation profiling, and profiling of selected histone modifications. We will also leverage natural variation in Brachypodium drought response and previous DOE investments by analyzing progressive drought experiments using three accessions of Brachypodium whose genomes have been sequenced by DOE-JGI: the reference genome accession, Bd21; the drought-susceptible accession Bd3-1; and the drought-tolerant accession Bd1-1.
The information obtained in this project will aid basic and applied research on a wide range of bioenergy grasses and accelerate deployment of improved grass crops, and will also yield genomic data resources useful for the plant research community and valuable for other studies. This project builds upon previous investments in genomic resources for bioenergy and will address several key interests of the program including investigating environmental influences on gene expression and phenotypes and adaptations to abiotic stresses, with an emphasis on water use efficiency in a model bioenergy grass crop. The large experimental datasets generated by this project will be used to develop computational models and approaches to predict plant performance in varying environmental conditions, with the aim of translation to informed breeding programs for bioenergy grass feedstocks.
Name: Mockler, Todd