Respiratory Activities, Cytochrome Composition and CytochromecOxidase Subunit II Levels of Mitochondria from Alloplasmic Wheats HavingAegilopsCytoplasms

摘要

Respiratory activities, cytochrome composition and cytochromecoxidase (EC 1.9.3.1) subunit II (COXII) levels of isolated mitochondria in one euplasmic and four alloplasmic lines of wheat (Triticum aestivum), having cytoplasms ofAegilops columnaris, Ae.crassa(4×),Ae. muticaandAe. triuncialis, which show various growth abnormalities, were studied. Cytoplasm-specific variation on the respiratory activities has been revealed among the cytoplasms of fiveTriticumandAegilopsspecies. The cyanide-resistant respiratory pathway does not seem to contribute to the variation in activity. The low level of state 3 and cytochrome oxidase activities were evident in lines havingAe. columnarisandAe. triuncialiscytoplasms, which also show growth inhibition. The low cytochrome oxidase activity in both cytoplasms is consistent with the low amount of cytochromeaa3and the severe reduction in COXII levels. The relatively low amount of cytochromeaa3inAe. muticais also consistent with the reduced level of the COXII. On the other hand, relatively low amounts of cytochromeb(b-557) are found in theAe. crassacytoplasmic line. These results suggest that the growth abnormalities found in the alloplasmic wheat lines are related to the variation in respiratory activities and cytochrome composition. In particular, growth inhibition found in the alloplasmic wheats havingAe. columnarisandAe. triuncialismay be caused by the severe depression of respiratory activity due to the impaired cytochrome oxidase activity of their mitochondria