Development of a reduced linolenate soy mutant by Re-irradiation and its genetic analysis

A high content of linolenic acid leads to reduction of keeping quality and frying stability of cooking oil. The present study was conducted to obtain a further reduction of linolenic acid in soybean [Glycine max (L.) Merr.] o il by re-irradiation of M-5 and determine its genetic system. M-5 is a muta nt with 4.5% linolenic acid content, derived from the cultivar Bay (8.0% li nolenic acid). A seed lot from line M-5 was treated with X-ray irradiation and M-2 plants were obtained from randomly selected seeds of M-1 plants. Th e M-2 plants were screened for reduced linolenic acid. One plant was found with 3.0% linolenic acid content and was named MS382. The M-3 and M-4 gener ations of this line proved that the character was fixed and significantly l ower than the M-5 control. For inheritance studies, MS382 was reciprocally crossed with M-5 (fan) and LOLL [fanfanx(a), a recombinant of M-5 (fan) x M 24 (fanx(a))]. The F-2 segregation ratio and the segregation of F-3 seeds f rom F-2 plants of MS382 x M-5 indicated that reduced linolenic acid in MS38 2 was conbindly controlled by fan (M-5) and an additional gene. To determin e if this additional gene was similar with the fanx(a) gene in LOLL, F-2 se eds and F-3 seeds from each F-2 plant of MS382 x LOLL were evaluated. No tr ansgressive segregation for linolenic acid was found in this cross, indicat ing the genes for reduced linolenic acid content in MS382 and LOLL were ide ntical. However, the mutant MS382 was developed by reirradiation which indi cates the practicability of this technique to develop new gene for further reduction of linolenic acid in soybean oil.