Folate derivatives in healthy and rust-infected primary leaves of wheat

Abstract

Six days after inoculation, crude extracts were prepared from healthy and rust-infected wheat leaves of a susceptible line and from healthy and rust-infected wheat leaves of a resistant line. Extracts from rust-infected leaves of both lines contained 50% more folates, active as growth factors for Lactobacillus casei, than did those from healthy leaves. Rust-infected leaves did not differ from healthy leaves in their content of folates active as growth factors for Streptococcus faecalis and Pediococcus cerevisiae.All extracts were fractionated on DEAE-cellulose columns. The eluate fractions were treated with chicken pancreas conjugase and assayed with L. casei. All extracts yielded similar folate profiles consisting of five major and three minor peaks. Conjugase treatment and differential assay of the peak fractions with L. casei, S. faecalis, and P. cerevisiae indicated that the eluates contained folates methylated at N-5 and folates formylated at N-10 in various states of oxidation and conjugation. The eluates also contained a compound believed to be 5-formyltetrahydropteroylglutamate, small amounts of pteroylglutamate, traces of tetrahydropteroylglutamate, and several unidentified folates.The increase of folate levels in rust-infected leaves was due almost entirely to increases of 5-methyl-tetrahydropteroylgiutamate and its conjugates. The folate composition of resistant-reacting leaves did not differ appreciably from that of susceptible-reacting leaves.Radioactivity was not incorporated into either 5-methyltetrahydropteroyltriglutamate or into methionine when 5-[methyl-14C]-tetrahydropteroylglutamate was fed to wheat leaves.