Comparative genetic mapping and a consensus interspecific genetic map reveal strong synteny and collinearity within the genus.

Introduction: Useful germplasm for citrus breeding includes all sexually compatible species of the former genera , and , now merged in the single genus. An improved knowledge on the synteny/collinearity between the genome of these different species, and on their recombination landscapes, is essential to optimize interspecific breeding schemes.

Method: We have performed a large comparative genetic mapping study including several main clades of the genus.

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

Despite their importance in food processing, perfumery and cosmetics, the inheritance of sweet orange aromatic compounds, as well as their yield in the fruit peel, has been little analyzed. In the present study, the segregation of aromatic compounds was studied in an F1 population of 77 hybrids resulting from crosses between clementine and blood sweet orange. Fruit-peel essential oils (PEOs) extracted by hydrodistillation were analyzed by gas chromatography coupled with flame ionization detection.

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

Orange ( var ) 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.

Genetic, morphological and chemical investigations reveal the genetic origin of Pompia (C. medica tuberosa Risso & Poiteau) - An old endemic Sardinian citrus fruit.

Citrus fruits have been introduced to the Mediterranean area from Asia for centuries and spontaneous crosses have generated several hybrid forms, some of which have had agricultural or industrial success while others have remained niche food or ornamental products, or have disappeared. Pompia (C. medica tuberosa Risso & Poiteau) is an old endemic citrus fruit from Sardinia of unknown genetic origin.

Genotyping by sequencing can reveal the complex mosaic genomes in gene pools resulting from reticulate evolution: a case study in diploid and polyploid citrus.

Background And Aims: Reticulate evolution, coupled with reproductive features limiting further interspecific recombinations, results in admixed mosaics of large genomic fragments from the ancestral taxa. Whole-genome sequencing (WGS) data are powerful tools to decipher such complex genomes but still too costly to be used for large populations. The aim of this work was to develop an approach to infer phylogenomic structures in diploid, triploid and tetraploid individuals from sequencing data in reduced genome complexity libraries.

Preferential Homologous Chromosome Pairing in a Tetraploid Intergeneric Somatic Hybrid ( + ) Revealed by Molecular Marker Inheritance.

The creation of intergeneric somatic hybrids between and is an efficient approach for citrus rootstock breeding, offering the possibility of combining beneficial traits from both genera into novel rootstock lineages. These somatic hybrids are also used as parents for further tetraploid sexual breeding. In order to optimize these latter breeding schemes, it is essential to develop knowledge on the mode of inheritance in the intergeneric tetraploid hybrids.

The Distribution of Coumarins and Furanocoumarins in Citrus Species Closely Matches Citrus Phylogeny and Reflects the Organization of Biosynthetic Pathways.

Citrus plants are able to produce defense compounds such as coumarins and furanocoumarins to cope with herbivorous insects and pathogens. In humans, these chemical compounds are strong photosensitizers and can interact with medications, leading to the "grapefruit juice effect". Removing coumarins and furanocoumarins from food and cosmetics imply additional costs and might alter product quality.

Cytological and molecular characterization of three gametoclones of Citrus clementina.

Background: Three gametoclonal plants of Citrus clementina Hort. ex Tan., cv.

A reference genetic map of C. clementina hort. ex Tan.; citrus evolution inferences from comparative mapping.

Background: Most modern citrus cultivars have an interspecific origin. As a foundational step towards deciphering the interspecific genome structures, a reference whole genome sequence was produced by the International Citrus Genome Consortium from a haploid derived from Clementine mandarin. The availability of a saturated genetic map of Clementine was identified as an essential prerequisite to assist the whole genome sequence assembly.

Genetic and chemical diversity of citron (Citrus medica L.) based on nuclear and cytoplasmic markers and leaf essential oil composition.

Native to southeast Asia, the citron (Citrus medica L.) was the first citrus fruit to be introduced to the Mediterranean area, in the third century BC, and remained its only citrus representative until the tenth century. The citron was used for its aroma - stemming from its essential oils in leaves and fruit peels - and as symbols in the Jewish religion.

Evidence for non-disomic inheritance in a Citrus interspecific tetraploid somatic hybrid between C. reticulata and C. limon using SSR markers and cytogenetic analysis.

Artificial tetraploid somatic hybrids have been developed for sterile triploid citrus breeding by sexual hybridization between diploid and tetraploid somatic hybrids. The genetic structure of diploid gametes produced by tetraploid genotypes depends on the mode of chromosome association at meiosis. In order to evaluate tetraploid inheritance in a tetraploid interspecific somatic hybrid between mandarin and lemon, we performed segregation studies using cytogenetic and single sequence repeat molecular markers.

Inheritance of characters involved in fruit quality in a citrus interspecific allotetraploid somatic hybrid.

The main components of citrus fruit quality (organic acids, sugars, and aromatic compounds) were studied in fruits of a somatic hybrid allotetraploid between Willow leaf mandarin (Citrus deliciosa Ten.) + Eureka lemon [Citrus limon (L.) Burm.

Transferability of the EST-SSRs developed on Nules clementine (Citrus clementina Hort ex Tan) to other Citrus species and their effectiveness for genetic mapping.

Background: During the last decade, numerous microsatellite markers were developed for genotyping and to identify closely related plant genotypes. In citrus, previously developed microsatellite markers were arisen from genomic libraries and more often located in non coding DNA sequences. To optimize the use of these EST-SSRs as genetic markers in genome mapping programs and citrus systematic analysis, we have investigated their polymorphism related to the type (di or trinucleotide) or their position in the coding sequences.

Induced parthenogenesis in mandarin for haploid production: induction procedures and genetic analysis of plantlets.

This study focused on haploid induction in mandarin through in situ gynogenesis by pollination with irradiated pollen of 'Meyer' lemon. Pollination was carried out for three genotypes of mandarin with four levels of gamma-ray-irradiated pollen (150, 300, 600, and 900 Gy). The resulting seeds were characterised by a small size.