RELATION OF DL‐HOMOCYSTEINE, DL‐METHIONINE, AND METHYL DONORS TO THE APHANOMYCES ROOT ROT OF PEAS

Abstract

Davey, C. B., and G. C. Papavizas. (Crops Res. Div., ARS, USDA, Beltsville, Md.) Relation of dl‐homocysteine, dl.‐methionine, and methyl donors to the Aphanomyces root rot of peas. Amer. Jour. Bot. 50(1): 67–72. 1963.—dl‐Homocysteine, a compound lacking a methyl (CH3) group, completely prevented Aphanomyces root rot of peas, whereas several CH3 donors (betaine, choline, dimethyl‐β‐propiothetin chloride, S‐methylmethionine) did not. dl‐Homocysteine was taken up by pea plants from nutrient solution and converted to methionine. The methylation of dl‐homocysteine in pea tissue occurred without an exogenous source of labile CH3 groups. More d‐ than l‐methionine was taken up by the plants and more methionine of both forms was taken up when methionine served as the sole sulfur source than when it was supplemented with sulfate. dl‐Methionine sulfoxide but not dl‐methionine sulfone was converted to methionine in pea tissues. Methionine derived from dl‐methionine sulfoxide was proportionately more abundant in the aerial portions of the plants.