The Effect of Acid Feeding on Amine Formation in Barley

It is probable that one of the functions of potassium in theplant is to maintain the ionic balance of the cell, and it hasbeen suggested that in potassium deficiency, the productionof organic bases such as putrescine serves to balance an excessof organic acids which might occur under these conditions. Themechanism for the increase in activity of the enzymes in thepathway leading to the formation of putrescine in potassium-deficientbarley leaves was studied, therefore, by investigating the effectof artificially increasing the acidity by feeding inorganicacids to the roots of barley seedlings. Feeding hydrochloric acid caused significant increases in L-argininecarboxy-lase (arginine decarboxylase) and N-carbamylputrescineamidohydrolase activity in the leaves when expressed on thebasis of fresh weight, dry weight, total nitrogen, or proteinnitrogen, and a similar increase was induced on feeding sulphuricacid. Acid feeding did not cause a significant change in potassiumcontent on a dry-weight basis. The arginine, agmatine, and putrescinecontents were increased in the acid-fed leaves. The possibilitythat the increased arginine content in the acid-fed leaves ledto an increase in arginine decarboxylase by enzyme inductionwas investigated by feeding arginine through the roots to barleyseedlings. No increase in decarboxylase activity could be detected.