Respiration of the Diseased Plant

Abstract

At the present time the factors controlling respiratory mechanisms are understood incompletely in normal plant cells. Because of this, it is difficult to interpret respiratory responses invoked by altered physiological states. With incomplete understanding of control in normal tissues, it is difficult to define the mechanism of increased respiratory rate frequently observed following infection. This means that the significance of this increase in the over-all symptoms of a disease cannot be assessed. Clearly one must distinguish between initial responses in early stages of infection and oxidative metabolism associated with degenerative changes. To accomplish this, attention should be paid to the histological state of the cells under investigation. When respiration is considered as a mechanism of energy production for synthetic reactions, the levels of respiratory and synthetic activities of the cell should be compared. Increased synthesis will be reflected in increased rate of ATP turnover. It should be possible to measure such turnover by incorporation of P32 phosphate. Correlation of respiratory rates with amounts of protein, DNA, and cell number, rather than with fresh and dry weights of tissues, provides a better estimate of the energy conserved. Such quantitative comparisons would indicate the extent to which electron transport to O2 is coupled with ATP synthesis.