Identification of quantitative trait loci for carbon isotope ratio in a recombinant inbred population of soybean

Authors: BAZZER, SUMANDEEP - University Of Arkansas; KALER, AVJINDER - University Of Arkansas; Ray, Jeffery - Jeff; Smith, James - Rusty; FRITSCHI, FELIX - University Of Missouri; PURCELL, LARRY - University Of Arkansas

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2020
Publication Date: 4/15/2020
Citation: Bazzer, S.K., Kaler, A.S., Ray, J.D., Smith, J.R., Fritschi, F.B., Purcell, L.C. 2020. Identification of quantitative trait loci for carbon isotope ratio in a recombinant inbred population of soybean. Theoretical and Applied Genetics. https://doi.org/10.1007/s00122-020-03586-0.
DOI: https://doi.org/10.1007/s00122-020-03586-0

Interpretive Summary: Drought is a major limitation to soybean yield, and the frequency of drought stress is likely to increase under future climatic scenarios. Water use efficiency is associated with drought tolerance and was measured in a genetically segregating soybean population over four field environments. The objective of this study was to identify DNA regions associated with water use efficiency. A total of 16 regions putatively associated with water use efficiency were identified on seven chromosomes. Molecular markers flanking the identified chromosomal regions were described and may be used to facilitate the accumulation of desirable genes associated with drought tolerance into soybean improved lines. The knowledge obtained from this research will be of use to soybean breeders in developing improved cultivars with drought tolerance.

Technical Abstract: Drought is a major limitation to soybean yield, and the frequency of drought stress is likely to increase under future climatic scenarios. Water use efficiency (WUE) is associated with drought tolerance, and carbon isotope ratio (d13C) is positively correlated with WUE. In this study, 196 F6-derived recombinant inbred lines from a cross of PI 416997 × PI 567201D were evaluated in four environments to identify genomic regions associated with d13C. There were positive correlations of d13C values between different environments (0.67 = r = 0.78). Genotype, environment, and genotype × environment interactions had significant effects on d13C. Narrow sense heritability of d13C was 90% when estimated across environments. There was a total of 16 QTLs on seven chromosomes with individual QTLs explaining between 2.5 to 29.9% of the phenotypic variation and with additive effects ranging from 0.07 to 0.22%. These 16 QTLs likely identified eight loci based on their overlapping confidence intervals. Of these eight loci, two loci on Gm20 were detected in at least three environments and were considered as stable QTLs. Additive QTLs on Gm20 showed epistatic interactions with 10 QTLs present across nine chromosomes. Six QTLs were identified across environments and showed significant QTL × environment interactions. These findings demonstrate that additive QTLs and QTL × QTL interactions play significant roles in genetic control of the d13C trait. Markers flanking identified QTLs may facilitate marker assisted selection to accumulate desirable QTLs to improve WUE and drought tolerance in soybean.