Characterization of soybean tissue culture cell lines resistant to methionine analogs.

Several hundred soybean [Glycine max (L.) Merr.] cell lines resistant to ethionine were isolated either with or without chemical mutagenesis. of these, 26 were found to contain 2 to 22 times higher than normal levels of uncombined methionine. These 26 cell lines also contained higher than normal levels of S-adenosylmethionine and S-methylmethionine, but the levels of free lysine, threonine, cysteine, valine, tyrosine and phenylalanine were not elevated. Isoleucine levels were only slightly elevated. These results suggest that the regulation of methionine synthesis in vivo is more likely to be later in the pathway (after homoserine phosphate) than early in the pathway.