Search

Nicotinamide nucleotide coenzymes were estimated spectrophotometrically in noninfected barley leaves and leaves infected with Erysiphe graminis var hordei (powdery mildew). Amounts of NADH, NADP(+) and NADPH were not altered by infection. In contrast, the NAD(+) content rose sharply and at 144 hours was 100% greater than in noninfected leaves. The respiratory rate was increased in infected leaves and the pattern of this increase was similar to that of NAD(+).The effect of infection on the intracellular distribution of NADP(+) was examined by fractionating lyophilized leaves in a nonaqueous medium. In noninfected leaves almost all of the NADP(+) was localized in the chloroplasts. In infected leaves where some chloroplast breakdown occurs, about 60% of the NADP(+) was detected in the nonchloroplast part of the cell. This intracellular redistribution of NADP(+) is discussed in relation to the increased pentose-P pathway activity occuring after infection.