An Additional QTL for Water Use Efficiency in Soybean
- M. A. R. Mian ,
- D. A. Ashley and
- H. R. Boerma
Water use efficiency (WUE) is one of the physiological traits that has been associated with drought tolerance in soybean [Glycine max (L.) Merr]. In a previous publication, we reported the identification of four quantitative trait loci (QTL) that conditioned WUE in a F4-derived soybean population obtained from a cross of ‘Young’ × PI416937. The purposes of this study were to identify WUE QTL in a F2-derived soybean population from a cross of ‘S100’ × ‘Tokyo’ and to determine the consistency of WUE QTL across the two soybean populations. A restriction fragment length polymorphism (RFLP) linkage map was created from 142 markers and 116 F2-derived lines of the population. The map covered about 1100 cM of the soybean genome with 120 markers linked on 25 linkage groups. Twenty-two of the markers remained genetically unlinked. The WUE of the parents and the F2-derived lines was evaluated in a greenhouse at Athens, GA, in 1996. S100 produced 9% more dry matter per unit of water used than did Tokyo. Progeny lines with greater WUE than S100 were identified in this population. Two independent markers were associated with WUE in this soybean population. There was no interaction between the two markers. One (A063E) of the two independent markers was also associated with WUE in the Young × P1416937 population. Marker A489H, on Linkage Group (LG) L, was unique to the S100 × Tokyo population and explained 14% of the variation in WUE in this soybean population. Interval mapping with MAPMAKER/ QTL indicated that the most probable location of the QTL on LG L was at marker locus A489H. The likelihood of odds (LOD) score for the presence of a QTL at this location was 3.4. Thus, we have identified a previously unreported QTL for WUE on LG L.
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