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ARS Home » Pacific West Area » Pullman, Washington » Plant Germplasm Introduction and Testing Research » Research » Publications at this Location » Publication #352464

Research Project: Enhancing Resistance to Diseases and Abiotic Stresses in Alfalfa

Location: Plant Germplasm Introduction and Testing Research

Title: Genomic Architecture and Phenotypic Plasticity of Forage Quality in Response to Water Deficit in Alfalfa (Medicago sativa L.)

item Yu, Long-Xi
item Boge, William
item HAWKINS, CHARLES - Washington State University
item FRANSEN, STEVE - Washington State University

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 12/10/2017
Publication Date: 1/12/2018
Citation: Yu, L., Boge, W.L., Hawkins, C., Fransen, S. 2018. Genomic Architecture and Phenotypic Plasticity of Forage Quality in Response to Water Deficit in Alfalfa (Medicago sativa L.). Meeting Abstract.

Interpretive Summary: Plant phenotypic plasticity is the ability for plants to cope with environmental factor variability. However, mechanisms by which phenotypic plasticity affects plant adaptation to environmental change remain largely unknown. It is important to identify plant functional traits in which plasticity may play a critical role in plant response to the environmental change. In the present study, we characterized 31 forage quality traits in alfalfa populations and analyzed the phenotypic plasticity of these traits in response to a gradient of water deficit. The plasticity index (PI) varied among the traits with the highest PI value (1.1) for K content and lowest (0.2) for dry matter. Fiber contents such as lignin, ADF and NDF decreased as drought increased. In contrast, energy traits were increased as drought increased. Correlation coefficients between the quality traits were increased as drought increased. Genetic factors were also characterized using genotyping by sequencing and genome-wide association studies. Single nucleotide polymorphisms associated with the traits were identified. Genomic architectures for phenotypic plasticity were analyzed for each trait and compared between the traits. Genomic regions responsible for the traits were identified and characterized. The possible roles of the genetic factors affecting phenotypic plasticity of forage quality in alfalfa were discussed.

Technical Abstract: A panel of alfalfa cultivars and landraces originated worldwide with potential value of drought tolerance were selected from USDA-Western Region Plant Germplasm Center. Field trials were conducted in the in Roza farm in Prosser, WA and a gradient of water deficits were applied. Aboveground biomass were harvested and evaluated for forage quality using Near Infrared Reflectance Spectroscopy (NIRS). Higher correlation was found between energy-related traits. The correlations among fiber-related traits decreased or maintained as drought increased, while those among energy-related traits increased as drought increased. Similar trends were found in the regression analysis. Great phenotypic plasticity variations were found in 200 alfalfa cultivars and landraces evaluated for drought resistance in the field trail. Genetic regions for forage quality were identified and compared between the quality traits. Similar regions were found between energy-related traits with higher correlations. Significant markers associated with forage quality under deferent irrigation episodes were identified. Common and specific markers were found among deferent levels of drought treatments. After validation, the markers closely linked to the quality loci can be used for MAS in breeding alfalfa with improved forage quality.