Correspondence between the Compositional and Aromatic Diversity of Leaf and Fruit Essential Oils and the Pomological Diversity of 43 Sweet Oranges (Citrus x aurantium var sinensis L.)

Abstract

Orange (Citrus x aurantium var sinensis) is the most widely consumed citrus fruit, and its essential oil, which is made from the peel, is the most widely used in the food, perfume, and cosmetics industries. This citrus fruit is an interspecific hybrid that would have appeared long before our era and would result from two natural crosses between mandarin and pummelo hybrids. This single initial genotype was multiplied by apomictic reproduction and diversified by mutations to produce hundreds of cultivars selected by men essentially based on phenotypic characteristics of appearance, spread of maturity, and taste. Our study aimed to assess the diversity of essential oil composition and variability in the aroma profile of 43 orange cultivars representing all morphotypes. In agreement with the mutation-based evolution of orange trees, the genetic variability tested with 10 SSR genetic markers was null. The oils from peels and leaves extracted by hydrodistillation were analyzed for composition by GC (FID) and GC/MS and for aroma profile by the CATA (Check All That Apply) method by panelists. Oil yield varied between varieties by a factor of 3 for PEO and a factor of 14 for LEO between maximum and minimum. The composition of the oils was very similar between cultivars and was mainly dominated by limonene (>90%). However, small variations were observed as well as in the aromatic profile, with some varieties clearly distinguishing themselves from the others. This low chemical diversity contrasts with the pomological diversity, suggesting that aromatic variability has never been a selection criterion in orange trees.

Inheritance and Quantitative Trait Loci Mapping of Aromatic Compounds from Clementine (Citrus × clementina Hort. ex Tan.) and Sweet Orange (C. × sinensis (L.) Osb.) Fruit Essential Oils

“…The F1 population consisted of 92 hybrids from two crosses: clementine (SRA 63) ( C. × clementina ) × Sokotoro sweet orange (SRA 407) ( Citrus × sinensis ) and clementine (SRA 63) × Moro sweet orange (SRA 301). The two populations can be considered one because the two sweet orange cultivars originated from the same “bloody pulp” group, and their PEOs did not differ in composition or quality [ 2 ]. Sweet oranges evolved only by mutations modifying very few phenotypic characters, such as pulp coloration due to anthocyanin synthesis [ 38 ].…”

“…1 Linkage groups: here each linkage group is associated with the scaffold corresponding to the physical map of the clementine tree. 2 Genetic position: the first value describes the first genetic position above the significance threshold, the second describes the max LOD position and the third describes the last position above the significance threshold. 3 Physical positions of the markers corresponding to the genetic positions of the QTLs.…”

“…is the most widely produced citrus fruit in the world. The orange juice industry generates approximately 60,000 tons of peel essential oils (PEOs), which represent a major product for flavoring beverages food products, and cosmetics [ 1 , 2 ]. The main volatile compounds of the essential oils present in the oil glands of sweet orange peel are monoterpenes, followed by aliphatic compounds and sesquiterpenes [ 3 ].…”

“…[ 19 ]. Sweet orange has been spread over the centuries by vegetative propagation (initially by somatic embryony and since a few centuries ago by grafting), and its phenotypic diversification mainly relies on mutation selection [ 2 ]. Sweet orange was the first citrus species whose genome was sequenced [ 20 ].…”