Advances in QTL mapping for ethylene production in apple (Malus×domestica Borkh.)

Ethylene is a gaseous hormone that coordinates several important physiological processes resulting inthe final fruit quality in apple. Due to its genetic heterozygousity, apple offers the possibility to exploit thenatural allelic variation existing at the level of two genes involved in the ethylene biosynthetic pathway,Md-ACS1 and Md-ACO1. The allelism of these two genes can be exploited for the advanced selection ofgenotypes characterized by low ethylene production, with a consequent extended postharvest storability. The impact of these two elements in ethylene control was verified using two specific apple populations(‘GDxBr’ and ‘FjxMG’) presenting distinct allelotype configurations. In the first progeny, two QTLs wereidentified in genetic positions corresponding with these genes, and for the first time the association of aQTL for ethylene production with Md-ACO1 in apple was established. However, the analysis carried out onthe second population, homozygous for the allele of Md-ACS1 associated with a low ethylene production,suggested the possible involvement of other genetic elements in the regulation of ethylene production. Inthe end we also present, in parallel to the GC assessment, a novel methodology based on proton transferreaction-time of flight-mass spectrometry (PTR-ToF-MS) for a more reliable, fast and efficient monitoring of the ethylene production in apple