*Corresponding author. Present address: Department of Biochemistry, Mahatma Phule Krishi Vidyapeeth, Rahuri 413 722, India
Differential response in the leaves of tall and dwarf wheat to CO, an inhibitor of cytochrome oxidase and to SHAM, an inhibitor of alternative oxidase appears to be correlated with presence of Rht dwarfing genes. This was detected by in vivo nitrate reductase assay after CO treatment and direct O2 uptake in presence of SHAM. Pretreatment of the leaves with Triton X-100 at a concentration which specifically inhibits the accessibility of exogenous NAD(P)H to alternative oxidase, significantly enhanced the CO response as assessed, by in vivo NR assay. This supports the hypothesis that the competition for NADH between NR and mitochondrial respiration is regulated by NADH-dehydrogenase located on the outer surface of inner mitochondrial membrane.
Triticum aestivum, alternative oxidase, carbon monoxide, cytochrome oxidase, nitrate reductase, NADH-dehydrogenase
