GENETIC-RELATIONSHIPS OF SOYBEAN MUTANTS FOR DIFFERENT LINOLENIC ACIDCONTENTS

The normal content (80-90 g kg(-1)) of linolenic acid in soybean [Glyc ine max (L,) Merr.] oil adversely affects oil flavor and stability. A new mutant (M-24) with lower linolenic acid content (62 g kg(-1)) was developed by x-ray irradiation. Our objective was to determine the inh eritance of linolenic acid content in M-24 and to determine the geneti c relationship of this trait with the fan and fanx loci known to contr ol linolenic acid in M-5 and KL-8 mutants, respectively. Reciprocal cr osses were made between each mutant and 'Bay', and among the three mut ants. No maternal or cytoplasmic effects were observed in any of the c rosses. Data from F-2 seeds of the cross M-24 x Bay indicated that lin olenic acid content in M-W was controlled by an allele at a single loc us with no dominance effects. In the cross of M-24 x KL-8, F-2 segrega tion indicated that linolenic acid content in M-24 and KL-8 was contro lled by two different alleles at the same Locus. For the M-5 x M-24 cr oss, I; segregation patterns and the segregation of F-3 seeds from ind ividual F-2 plants indicated that M-5 and M-24 mutants have alleles at different independent loci that control linolenic acid content. there fore, the allele in M-24 is designated as fanx(a) (M-24) to distinguis h it from those of fan (M-5) and fanx (KL-8). The segregate with the f anfanfanx(a)fanx(a) genotype can be considered as an important germpla sm that can reduce the linolenic acid content in soybean oil.