The Inheritance and Variation of Floral Scent Compounds in Parent–Progeny Relationships of Malus

Improving floral scent quality is an important goal in Malus breeding. However, the inheritance regularity for volatile components of Malus remains unclear. In this study, the floral scent compounds and scent characteristics of five Malus taxa with clearly defined parent–progeny relationships were analyzed by sensory evaluation, an electronic nose, and gas chromatography–mass spectrometry. A total of 51 volatile compounds were identified in five taxa. M. ioensis showed the highest sensory intensity with the maximum total content of compounds (8247.59 ng·g−1 FW·h−1). Compared to its progenies and ‘Lemoinei’, terpenoid compounds in M. ioensis accounted for the largest proportion (40.46%). Most compounds in the progenies were inherited from their maternal parent (60.61–75.00%), and most of them were significantly downregulated by hybridization. However, the content of several compounds in the progenies appeared transgressive, even unique. Progenies and their maternal parents exhibited similar sensory characteristics: earthy/woody, sweet, and rose. The content of characteristic compounds (geranylacetone, 6-methyl-5-hepten-2-one, 2-phenylethanol, α-ionone, β-ionone, decanal, and so on), total content, and the response of sensor W3S positively correlated with scent intensity. The response of sensor W1W correlated significantly and positively with the compound number and the total content. Our findings provided a reference for tracking maternal parents for cultivars and enabled rapid selection of fragrant flower cultivars by electronic nose.