Abstract:

【Objective】 Comparison of accumulation pattern of oil and protein between different genotype parent lines and their recombinant inbred lines (RIL) were made to determine how C partitioning into protein or oil in high protein genotypes was achieved and transmitted to progeny selected from crossing between high and low protein parents, which will provide a reference for breeding high protein and high yield soybean seeds. 【Method】 Three genotypic soybean lines (Glycine max L. Merr.), high protein PI(H), low protein PI(L), high yield and low protein parent Evans (E), were used as parent lines and crossed E with H (HxE) and L (LxE) respectively. Then, high protein RIL (HH and LH ) and high oil lines RIL (HL, LL) were selected from HxE and LxE. The seeds of parent lines and RIL were grown in the field. Pods were harvested at 5 d interval from18 d until yellow pod stage yellow. Seed components in the seeds collected from each stage were tested. 【Result】 The seed developmental period of parent lines H and L (48 d) was shorter a that of parent line E (60 d) with plant height, more pods in the plant, but former had higher growth rate than later. RIL with high protein (HH) had similar growth pattern to high protein parent line (H),RIL with low protein (LL) similar to low protein parent line (L) and high yield line (E). The developmental pattern of DW partitioning into protein and oil varied with protein genotype in later season. In the later season of seed development, the protein content in H continued to increase until maturity, while that in L and E accumulated relatively slow. Oil content in H peaked at about 40 DAF and continued to accumulate in .L and E after 40 DAF. In different cross combinations, accumulation patterns of protein and oil in RILs HH (70) and LH(372) selected for high protein were the same as parent H with high protein. While RILs selected for low protein LL(389) and HL(42) had similar accumulation pattern of protein and oil to parent E. In same cross combination, protein content was varied in RIL, accumulation patterns of protein and oil in HH (70) were similar to H, while RILs HL (42) resembled the pattern in E.【Conclusion】 The protein and oil contents in mutured seeds were determined by C partitioning during the development of the seeds. RILs segregated with differences in protein and oil content were associated with partitioning of C into protein continued after mid fill. This result indicates that improving protein content requires a greater understanding of mechanisms regulating assimilate flux within the embryo.

Key words: genetic lines of soybean, recombinant inbred lines, accumulation pattern of protein and oil, partition of C