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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #340727
Title: Genome-wide association mapping of carbon isotope and oxygen isotope ratios in diverse soybean genotypes

Author
item KALER, AVJINDER - University Of Arkansas
item DHANAPAL, ARUN - University Of Missouri
item Ray, Jeffery - Jeff
item KING, ANDY - University Of Arkansas
item FRITSCHI, FELIX - University Of Missouri
item PURCELL, LARRY - University Of Arkansas

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2017
Publication Date: 9/14/2017
Citation: Kaler, A., Dhanapal, A., Ray, J.D., King, A., Fritschi, F., Purcell, L. 2017. Genome-wide association mapping of carbon isotope and oxygen isotope ratios in diverse soybean genotypes. Crop Science. 57:1-16.

Interpretive Summary: Drought is a major factor limiting soybean yield. Higher water use efficiency is a potential trait to reduce the impact of drought but it is difficult and expensive to measure in field experiments with many individual soybean genotypes. However, measuring the relative levels of carbon and oxygen elemental forms in the tissue allows scientists to estimate water use efficiency and transpiration more economically. These metrics were measured on a diverse collection of 373 soybean genotypes grown in four field environments. Additionally, data for over 30,000 molecular markers across the 373 genotypes were used to identify specific regions on chromosomes associated with putative water use efficiency and transpiration. Multiple chromosomal regions were identified, and differential genes in these regions may be combined through plant breeding to improve drought tolerance in soybean.

Technical Abstract: Water deficit stress is a major factor limiting soybean [Glycine max (L.) Merr.] yield. High water use efficiency (WUE) offers a means to potentially ameliorate drought impact, but increased WUE is often associated with a reduction in transpiration (T) and an accompanied reduction in photosynthesis. This interdependence of T and photosynthesis is a major constraint in selection for high WUE by breeding programs. Measurement of genetic variability in WUE and T through carbon isotope ratio (d13C) and oxygen isotope ratio (d18O), respectively, could be important in identifying genotypes with high WUE that also have relatively high T, and hence, higher rates of biomass production. This study’s objective was to identify genomic regions associated with d13C and d18O. A diverse collection of 373 soybean genotypes was grown in four field environments and whole-plant samples collected at early reproductive growth were characterized for d13C and d18O. After quality assessment, 31,260 polymorphic SNP markers with a minor allele frequency (MAF) = 5% were used for association analysis. Genome-wide association analysis identified 54 environment-specific SNPs associated with d13C and 47 SNPs associated with d18O. These SNP markers tagged 46 putative loci for d13C and 21 putative loci for d18O, and may represent an important resource for pyramiding favorable alleles for drought tolerance and identifying genotypes with high WUE.