Identifying Differences in Abiotic Stress Gene Networks between Lowland and Upland Ecotypes of Switchgrass

2012 Awardee

Investigators: Kevin Childs (MSU), C. Robin Buell (MSU), Bingyu Zhao (VirginiaTech), Xunzhong Zhang (VirginiaTech)

Institutions: Michigan State University, Virginia Polytechnic Institute and State University

Non-Technical Summary: Switchgrass is a North American grassland species that has been identified as a promising lignocellulosic biofuel feedstock species. The lowland and upland ecotypes of switchgrass have contrasting agronomic traits. Lowland ecotypes are taller, produce more biomass, typically grow at more southerly latitudes and are often characterized as drought sensitive. Upland ecotypes are short statured, produce less biomass, are typically found in northerly latitudes and often tolerate drier growth conditions. We will conduct research to investigate the responses to drought and salt stress in a diverse collection of lowland and upland switchgrass ecotypes by correlating gene expression patterns with growth and metabolite levels in order to more fully characterize the role of key switchgrass genes and gene pathways during drought and salt stress. By comparing differential gene expression between tolerant and sensitive lines of switchgrass we will develop a better understanding about how switchgrass responds to drought and salt stress. This work will also allow us to identify genes and germplasm that can be used to improve cultivated switchgrass to better tolerate these abiotic stresses.

Objectives: (1) Characterize lowland and upland switchgrass cultivars for physiological, morphological and metabolic responses to drought and salinity to identify cultivars that are tolerant and sensitive to these abiotic stresses. (2) Profile gene expression patterns in four switchgrass lines with extreme tolerant/sensitive responses to drought and salt stress.  Profile transgenic switchgrass lines overexpressing homologs of known drought and salt stress transcription factors. (3) Construct and compare gene coexpression network modules found in tolerant/sensitive cultivars and transgenic lines.  Physiological, morphological and metabolic phenotypes will be correlated with gene network modules to develop a systems-level understanding of drought and salinity stress responses. (4) Incorporate gene network results into the existing Biofuel Feedstock Genomics Resource website.

Approach: This project will initially screen a diverse collection of switchgrass lines for responses to drought and salt stress. We will examine growth characteristics such as height, tiller number, and total biomass. We will perform metabolic analyses to quantify sugars, amino acids, plant hormones and other stress-related compounds. After initial characterization of the responses to drought and salt stresses, we will examine gene expression patterns in response to drought and/or salt treatment over a three-week time course in two stress-tolerant and two stress-sensitive switchgrass lines. We also will develop transgenic switchgrass lines that overexpress transcription factors known to be involved in drought and salt response. Transgenic plants will also be subjected to drought and/or salt treatment over a three-week time course. Morphological, metabolic and gene expression analyses will be performed on all time-course experiments. Gene coexpression analysis will identify collections of genes that have similar expression patterns, and gene expression patterns will be correlated with growth and metabolic measurements to identify genes involved in salt and drought stress responses in switchgrass.

Project Contact
Name: Kevin Childs
Phone: 517-775-2844
Fax: 517- 353-1926
Email: [email protected]