Abstract Detail

Genetics

Johnson, Loretta [1], Galliart, Matthew [2], Bello, Nora [3], Poland, Jesse [4], St Amand, Paul [5], Knapp, Mary [6], Maricle, Brian [7], Baer, Sara [8], gibson, David [8].

Adaptive Ecotypic Variation and Genetic Divergence of an Ecologically Dominant Prairie Grass across the Great Plains’ Precipitation Gradient.

Local adaptation is fundamental to evolution, conservation, and climate change. Andropogon gerardii, big bluestem, a C4 warm season grass, represents ~70% of Great Plains prairie biomass. Big bluestem has a wide geographic distribution across a precipitation gradient (500-1200 mm/yr, western KS to IL) and is hypothesized to have adaptive variation in response to climate. Objectives were to use reciprocal gardens to investigate differences among ecotypes in phenotypic traits, gene expression, and genetic divergence. Ecotypes (CKS, EKS, and SIL, derived from central, eastern KS and southern IL, respectively) were reciprocally planted in Colby, Hays, and Manhattan, KS, and Carbondale, IL. We evaluated ecotype differences in vegetative and reproductive traits, utilized RNASeq to investigate differential gene expression and Genotyping-by-Sequencing to characterize genetic divergence. Canopy area and height increased from west to east, with no ecotype differences in western KS (all plants dwarfed). In Carbondale and Manhattan, the xeric ecotype (CKS) flowered approximately 20 days earlier than other ecotypes. Morphology was primarily associated with seasonal mean temperature and seasonal mean precipitation. Gene expression analyses indicated that genes involved with water stress and were upregulated in the mesic ecotype (SIL) under dry conditions. Using UNEAK, we identified 4,641 SNPs. Outlier analysis identified 373 SNPs showing divergent selection, putatively associated with seasonal diurnal temperature variation and seasonal precipitation. SNPs were aligned to the Sorghum bicolor genome for gene annotation. Candidate genes identified as outliers include: glutamate synthase (nitrogen assimilation), GA1 (internode length), and WUSCHEL transcription factor (development). Results provide insight into candidate genes responsible for adaptive divergence among ecotypes. Ultimately, this research will inform land managers as to what ecotypes are best suited for prairie conservation and restoration for drier climates. Such studies are crucial to understand big bluestem response to climate, particularly with the recent drought in 2012, the worst in ~50 years.

1 - Kansas State University, Biology, Ackert Hall Rm 232, Manhattan, KS, 66506-4901, USA
2 - Kansas State University, Biology,, Ackert Hall Rm 232, Manhattan, SA, KS, 66506-4901, US
3 - Kansas State University, Statistics, Dickens Hall, Manhattan, SA, KS, 66506, United States
4 - Kansas State University, Plant Pathology, Throckmorton Hall, Manhattan, KS, 66506, United States
5 - Hard Wheat Genetics Resource Center, USDA-ARS, Manhattan, SA, KS, 66506, United States
6 - Kansas State University, Agronomy, Throckmorton Hall, Manhattan, SA, KS, 66506, United States
7 - Fort Hays State University, Department Of Biological Sciences, 600 Park St., Hays, KS, 67601-4099, USA
8 - Southern Illinois University, Plant Biology, Carbondale, IL, US

Keywords:
ecotypes
grassland
genotype
RNA Seq
Genotyping by sequencing (GBS).

Presentation Type: Oral Paper
Session: 11, Genetics
Location: 105/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 2:00 PM
Number: 11003
Abstract ID:680
Candidate for Awards:Margaret Menzel Award