The polymorphism of ACS1 and ACO1 genes in some Malus species

Abstract

The allelic polymorphism of ACS1 and ACO1 genes, encoding for ACC synthase and ACC oxidase that catalyze the last two reactions in the ethylene biosynthetic pathway, were analyzed in the following nine Malus species from the ex situ collection of the Fruit Research Institute (FRI), Cacak, Republic of Serbia, i.e., Malus x atrosanguinea (Spaeth) Schneid., Malus floribunda Siebold ex Van Houtte, Malus hupehensis (Pamp.) Rehder, Malus x micromalus Makino, Malus niedzwetzkyana Dieck, Malus prunifolia (Willd.) Borkh. var. microcarpa, Malus prunifolia (Willd.) Borkh. var. xanthocarpa, Malus sargentii Rehder and Malus sieboldii (Regel) Rehder. The alleles were revealed by polymerase chain reaction (PCR) for ACS1 gene and additional restriction analysis of PCR product for ACO1 gene with two restriction enzymes (BamH1 and RsaI). The PCR product of 490 bp corresponded to the ACS1-1 allele and homozygosity of this allele was identified in all of the assessed Malus species. The comparison of polymorphisms observed upon the restriction analysis [BamH1 - two segregating fragments of 700 bp (f(1) fragment) and 760 bp (f(2) fragment); RsaI - three segregating fragments of 530 and 680 bp (together considered as f(1) fragment), 1,270 bp (f(2) fragment) and 1,050 bp (f(3) fragment)] resulted in the identification of four alleles of ACO1 gene - a, b, c and d, generating five genotypes (dd - four species, ac - one species, ad - two species, bd - one species and cd - one species). This study confirmed that allele d of the ACO1 gene has been detected only in the Malus wild species so far.