Most soybean cultivars have ovate leaflets, although a few cultivars have narrow or lanceolate leaflets. Narrow leaflet cultivars tend to have more seeds produced per pod than ovate leaflet cultivars, suggesting that the narrow leaflet trait is tightly linked to or cosegregating with the trait controlling number of seeds produced per pod (nspp). The objective of this study was to construct a high resolution map of a chromosomal region controlling narrow leaflet trait and nspp in soybean. A BC3F2 population from a cross between 'Sowonkong' and 'V94-5152' was used. Sowonkong have narrow leaflet and 4-seeded pod and V94-5152 have ovate leaflet and do not have 4-seeded pod. The plants of F2 populations showed a segregation ratio of 3:1 of ovate leaflet to narrow leaflet and then leaflet genotypes were obtained from F2:3 population of each F2 individual. The narrow leaflet-containing plants showed Sowonkong-like pod trait and the ovate leaflet-containing plants V94-5152-like pod trait. The results suggested that, in our mapping population, a single gene controls inheritance of the narrow leaflet character and the narrow leaflet trait is tightly linked to or co-segregating with the trait controlling nspp. Subsequently, we mapped the narrow leaflet locus near Sat_105, Satt270 and SM315 on soybean linkage group I that corresponds with the previously known ln locus. Work is ongoing to construct a fine molecular genetic linkage map on this MLG I region and to find a linkage relationship between ln and nspp. Our results should facilitate further elucidation for the relationship between ln/nspp and yield.

Pod shape of twenty soybean (Glycine max L. Merrill) genotypes was evaluated quantitatively by image analysis using elliptic Fourier descriptors and their principal components. The closed contour of each pod projection was extracted, and 80 elliptic Fourier coefficients were calculated for each contour. The Fourier coefficients were standardized so that they were invariant of size, rotation, shift, and chain code starting point. Then, the principal components on the standardized Fourier coefficients were evaluated. The cumulative contribution at the fifth principal component was higher than 95~% , indicating that the first, second, third, fourth, and fifth principal components represented the aspect ratio of the pod, the location of the pod centroid, the sharpness of the two pod tips and the roundness of the base in the pod contour, respectively. Analysis of variance revealed significant genotypic differences in these principal components and seed number per pod. As the principal components for pod shape varied continuously, pod shape might be controlled by polygenes. It was concluded that principal component scores based on elliptic Fourier descriptors yield seemed to be useful in quantitative parameters not only for evaluating soybean pod shape in a soybean breeding program but also for describing pod shape for evaluating soybean germplasm.