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

Vincent Ferrer,Mathieu Paoli,Patrick Ollitrault,Gilles Costantino,François Luro,Carole Quinton,Noémie Paymal,Félix Tomi

doi:10.3390/agronomy11061084

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.

Highlights

The regular sour orange belongs the Rutaceae family
Even if regular sour orange is resistant to citrus tristeza virus (CTV), if a sensitive scion is grafted onto sour orange and infected with CTV the defense mechanism of sour orange will induce a necrosis at the graft junction and death of the scion [6]
Three main genetic groups of C. × aurantium have been identified: a regular sour orange group represented by 39 varieties without intercultivar molecular diversity, a “Tosu” and “Gou Tou” pair, and “Australian” and “Fraser Seville” pair

Summary

Introduction

The regular sour orange belongs the Rutaceae family. Its genetic origin is commonly accepted to be direct hybridization between a pure male mandarin (C. reticulataBlanco) and a pummelo (C. maxima (Burm.) Merr.) [1,2]. The regular sour orange belongs the Rutaceae family. Sour orange was probably cultivated in India and China hundreds of years ago, before the Christian era [3]. Oil production is estimated to two hundred and twenty tons per year for leaves oil (petitgrain), to one ton per year for flower oil (neroli) and twenty-five to thirty tons/year for PEO [8,9]. This production is characterized by low volumes with high monetary value [10]. Tanaka’s classification distinguished numerous sour orange species (C. aurantium L., C. myrtifolia Raf., C. neoaurantium Tan . . . ), whereas Swingle and Reece described only one group, C. aurantium [11,12]

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