Intercultivar Diversity of Sour Orange (Citrus aurantium L.) Based on Genetic Markers, Phenotypic Characteristics, Aromatic Compounds and Sensorial Analysis

Abstract

Sour oranges (Citrus aurantium L.) are well known in the processing and cosmetics industries for the aromatic properties of their essential oils. Intercultivar genetic and aromatic diversity is not well documented. The objective of this study was to evaluate the impact of morphological selection and genetic mechanisms of varietal diversification (mutation or hybridization) on the aromatic and odor variability of sour orange essential oils. Forty-five sour orange accessions from INRAE-CIRAD citrus Biological Resources Center (France) were assessed for ten simple sequence repeat (SSR) and 54 single nucleotide polymorphism (SNP) markers, nine morphochemical fruit traits and with the aromatic components of leaf and peel essential oils. Thirty-nine sour oranges displayed no intercultivar molecular polymorphism and six genotypes originated from interspecific hybridizations involving sour orange, citron, pummelo or mandarin. The peel essential oil (PEO) diversity was low, in accordance with the genetic diversity. The predominance of limonene (>90%) prevents any possible correlation to be made between the composition and the variation in sensory profiles detected by panelists. Few compounds in the leaf essential oil (LEO), such as linalool, linalyl acetate, α-terpineol and geraniol were significantly different across sour oranges varieties. The morphological fruit attributes mainly used in varietal selection differed highly across the main genetically identical group of sour orange accessions. These results confirm that mutation can generate variability in aromatic compounds and aromas and that their exploitation requires an improvement in characterization processes.