Genetic analysis of net-like cracking in soybean seed coats
- Cite this article as:
- Nakamura, T., Yang, D., Kalaiselvi, S. et al. Euphytica (2003) 133: 179. doi:10.1023/A:1025541610329
Cracking of seed coats in soybean (Glycine max (L.) Merr.) deteriorates the external appearance of seeds and reduces their commercial value. Two types of cracking have been reported that occur in some cultivars: Type I with irregular cracks and Type II with net-like cracks. This study was conducted to determine the genetic basis of net-like cracking. Genetic analysis was performed using F1 plants produced by crossing Uzuramame, a Japanese landrace with black seed coats having net-like cracking and a Clark mutant with black seed coats, their F2 population and F3 lines. Degree of cracking in individual plants was calculated by averaging cracking index (no cracking: 0 to severe cracking: 4) of total or 100-seed samples (average cracking index, ACI). Uzuramame exhibited intense cracking, whereas the Clark mutant showed slight cracking. Intermediate degree of cracking in F1 plants suggested incomplete dominance. ACI of F2 plants was continuously distributed. Gene number involved was estimated to be 1.4 by Wright's method. All F3 lines derived from F2 plants with ACI more than 2.8 displayed severe cracking phenotypes. In contrast, F3 lines derived from F2 plants with ACI less than 2.8 segregated from low to high ACI (0.5 to 3.2). When F2 plants were classified as slight (ACI<2.8) or severe (ACI>2.8) cracking, the frequency distribution of the F2 plants fitted to a 3:1 ratio. Genotypes of SSR marker Satt264 that is closely linked to SoyPRP1 locus for proline-rich cell wall protein had a minor effect on ACI. Further, seed weight was positively associated with ACI (r =0.46**). Our results suggest that net-like cracking is controlled primarily by a major gene, and SoyPRP1 and gene(s) contributing to seed weight may have minor effects on the intensity of cracking.