DIFFERENCES IN KINETICS OF F-1-ATPASES OF CYTOPLASMIC MALE-STERILE, MAINTAINER AND FERTILITY RESTORED LINES OF SORGHUM

A comparative analysis of mitochondrial functions was carried out in t he cytoplasmic male sterile Al (mile) cytoplasm, its maintainer and th e fertility restored lines. The study of temperature dependence (15-45 degrees C) of the rates of uncoupled whole chain electron transport i n the three lines did not reveal any differences between them at any o f the temperatures studied. The partitioning of electrons between the cyanide-sensitive and the cyanide-insensitive respiratory pathways als o did not show any differences between the three lines. However, diffe rences in the kinetic properties of the isolated mitochondrial F-1-ATP ases between the sterile and the fertility restored lines were clearly observed. The studies revealed that while a strong negative cooperati vity between the subunits of the F-1-ATPases of the fertile maintainer and the fertility restored hybrid lines was observed, the F-1-ATPase from the sterile line, in contrast, showed much reduced negative coope rativity. It is proposed that these differences in kinetic properties of the F-1-ATPase may play a role in the expression of the CMS trait a t the time of anther formation. (C) 1997 Elsevier Science Ireland Ltd.