|LIU, XIANGPING - Washington State University
Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2017
Publication Date: 5/24/2017
Citation: Liu, X., Yu, L. 2017. Genome-wide association mapping of loci associated with plant growth and forage production under salt stress in alfalfa (Medicago sativa L.). Frontiers in Plant Science. 8:853. https://doi.org/10.3389/fpls.2017.00853.
Interpretive Summary: The development of alfalfa cultivars with the ability of tolerance to salt stress would be valuable in the reclamation of saline soils. However, it is difficult to develop a uniform, repeatable method for selecting alfalfa with the ability to germinate in the saline soil. Several techniques to screen alfalfa germplasm resistant to salt stress have been developed. In the present study, we used the standard protocol of forage prodcution under salt stress published in the NAAIC web page (http://www.naaic.org/). Using this protocol, we tested 200 diverse alfalfa accessions and identified a group of molecular markers asscoiated with salt tolerance. These markers can be used for marker-assisted selection in breeding alfalfa with improved salt tolerance when validated.
Technical Abstract: Salinity tolerance is highly desirable to sustain alfalfa production in marginal lands that have been rendered saline. In this study, we used a diverse panel of alfalfa accessions for mapping loci associated with plant growth and forage production under salt stress using genome-wide association studies (GWAS). The plants were genotyped using genotyping-by-sequencing (GBS). A greenhouse procedure was used for phenotyping four agronomic and physiological traits affected by salt stress, including biomass dry weight (DW), plant height (PH), leaf chlorophyll content (LCC) and stomatal conductance (SC). For each trait, a stress susceptibility index (SSI) was used to evaluate plant performance under stressed and non-stressed conditions. Marker-trait association identified a total of 42 markers significantly associated with salt tolerance. These markers were located on all chromosomes except chromosome 2 based on the alignment of their flanking sequences to the reference genome (Medicago truncatula). Of those identified, 13 were associated with multiple traits. Several loci identified in the present study were also identified in previous reports. BLAST search revealed that several salt resistance loci linked to functional genes that play roles in plant response to abiotic stress. With further investigation, these markers would be useful for marker-assisted selection to improve alfalfa cultivars with enhanced resistance to salt stress.