Abstract

Ahmed M El-Shehawi and Mona M. Elseehy

The orf256 gene is associated with cytoplasmic male sterile (CMS) wheat. The gene lies upstream of coxI in T. timopheevi (Tt) mitochondrial DNA (mtDNA) and is expressed with coxI in the same mRNA in Tt, fertility restored (FR), and CMS lines. It is not present in Triticum aestivum (Ta) mtDNA. The gene is expressed as a 7 kD protein only in CMS lines. Different transcripts were detected in the different mitochondrial sources. Orf256-coxI RNA binds to many protein from various wheat mitochondrial sources. Here, we report that there were various kinase activities in mitochondrial protein extracts of Ta and CMS wheats. Three bands of mitochondrial proteins were subject to phosphorylation by endogenous kinase activity that was differentially modulated by sodium vanadate. Dephosphorylation of mitochondrial protein extracts seems to decrease the kinase activity or make those protein bands less favorable substrates for the endogenous kinases. Staurosporine does not have major effect on the kinase activities. Results showed that there might be different kinases, one of which is modulated by sodium vanadate but not with staurosporine, in various mitochondrial protein sources. The variations in kinase activity may reflect proteomic variations among mitochondrial protein sources