Is Male-sterility in Plants Related to Lack of Cyanide-resistant Respiration in Tissues.'?

Cyanide-resistant (alternative) respiration by tissues of 7 male-sterile lines from 4 species (Glycine max (L.), Helenium amarum (Raf.) H. Rock., Plantago lanceolata L. and Zea mays L.) was compared with that of fertile tissues. Six of the 7 male-sterile lines lacked alternative respiration in the tissue assayed (leaf or root), while the corresponding fertile tissue displayed a typical alternative pathway equivalent to about 20% of the uninhibited respiratory rate. The exception to this pattern was the male-sterile maize line cytoplasmic male sterile (cms)-T, which had an alternative pathway equivalent to that of the fertile line. Mitochondria isolated from male-sterile cms-C maize were found to have an alternative pathway, but the capacity of this pathway was only one-half to two-thirds as large as that found in mitochondria from the male-fertile N line. Thus while no alternative pathway could be detected in intact cms-C tissue, it was found in the isolated mitochondria, suggesting that the pathway is somehow suppressed in the intact tissue. Since cytokinins are known to both inhibit the alternative pathway and affect floral development, they represent potential candidates for the suppressing agent involved. The lack of alternative respiration in the male-sterile lines might also serve to explain the commonly observed higher prodlw.kivity and vigor of male-sterile plants compared to fertile ones.