A single nucleotide polymorphism in the alternative oxidase gene among rice varieties differing in low temperature tolerance

Alternative oxidase (AOX) is encoded in a multigene family, and multiple isoforms have been observed in various plant species. We found for the first time an allelic variation in the same AOX locus. On SDS-gel blots of callus protein of rice (Oryza sativa L.), varieties without the QTL for low temperature tolerance showed a 32-kDa AOX band, whereas those with the QTL showed a 34-kDa band. The variation was attributed to the substitution of Lys(71) for Asn(71) caused by a single nucleotide polymorphism between alleles of OsAOX1a, and was tightly linked to the presence of the QTL. (C) 2002 Federation of European Biochemical Societies. Published by Elsevier Science B.V. All rights reserved.