Effect of Puccinia graminis tritici on Organic Acid Content of Wheat Leaves

Abstract

In previous work it has been established that rust-affected tissues have high rates of respiration mediated by a pentose pathway. A quantitative study of acids associated with the Krebs cycle was made in order to determine if oxidative pentose metabolism would lead to synthesis of organic acids or whether a cylic pentose pathway was involved. Organic acids were separated by gradient elution from dowex 1- X 8 columns in the formate form. During vegetative development there were marked increases in malic and succinic acids, during sporulation citric acid increased markedly. Changes in glutamic and aspartlc acids paralleled those of citric and malic respectively. The significance of the results are discussed with respect to the literature on obligate parasites.