Identification of ETR1 alleles in some Malus Miller species

Abstract

Wild Malus Miller species offer diversity essential for future breeding programmes that are not available within domestic and foreign apple cultivars. These species may provide novel alleles not just for disease resistance, but also for various desirable traits. Predicting and optimising the quality of stored apples and maximising their shelf life are becoming a major challenge worldwide. Ethylene regulates a broad spectrum of developmental and physiological processes in apple (including fruit ripening) and being perceived through the family of receptors, among which Ethylene Receptor 1 (ETR1) is one of the Subfamily I receptors, encoded by ETR1 gene. This study aimed to identify the ETR1 alleles in nine Malus Miller species from the ex situ collection of the Fruit Research Institute, Čačak, Republic of Serbia. The ETR1 alleles were revealed by polymerase chain reaction (PCR) and additional restriction analysis of amplified PCR product (~5,000 bp) with RsaI, AluI and HinfI enzymes. Upon comparison of the observed polymorphisms, six alleles of ETR1 gene (a, b, c, d, f and g) were identified, among which f and g alleles were revealed in this study for the first time. Further characterisation of the novel alleles will be performed through cloning and sequencing of the corresponding DNA fragments. The polymorphisms observed upon PCR amplification and subsequent digestion with aforementioned restriction enzymes were generated in six allelic constitutions for ETR1 gene ‒ bb (one species), bd (one species), bf (one species), b,a/c (three species), ff (two species) and g,a/c/d/g (one species).