Karyological Analysis and DNA Barcoding of Pompia Citron: A First Step toward the Identification of Its Relatives

Abstract

Pompia is a citrus fruit endemic of Sardinia, Italy, with an essential oil profile showing outstanding anti-inflammatory and anti-microbic properties. Despite its remarkable pharmaceutical potential, little taxonomic and genetic information is available for this species. We applied flow cytometry and classical cytogenetic techniques to assess the DNA content and to reconstruct the karyotype of several Pompia accessions. Molecular data from plastid DNA barcoding and nuclear DNA sequencing were used to study the genetic distance between Pompia and other citrus species. Flow cytometric estimates of DNA content and somatic chromosome counts suggest that Pompia is a regular diploid Citrus species. DNA polymorphisms of nuclear and chloroplast markers allowed us to investigate the genetic relationships between Pompia accessions and other Citrus species. Based on DNA polymorphism data we propose that Pompia is a very recent interspecific hybrid generated by a cross between C. aurantium (as seed bearer) and C. medica (as pollen donor). Our findings pave the way for further and more specific investigations of local Pompia germplasm resources that may help the preservation and valorisation of this valuable citrus fruit tree.

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

“…However, these two studies only considered a few genotypes: citron, lemon, sour orange, grapefruit and Volkamer lemon (Mignani et al, 2015), as well as three lemon varieties and one citron variety (Camarda et al, 2013). The use of barcoding (ITS) and cytoplasmic DNA fragment sequencing of 10 citrus genotypes suggested a putative contribution of sour orange and citron in the origin of Pompia (Viglietti et al, 2019). However, definitive conclusions about the origin of Pompia require more accurate genetic diversity studies based on an extended set of codominant nuclear and cytoplasmic markers, similar to that performed to identify the origin of Corsican citron (Luro et al, 2012).…”

Antioxidant, Antimicrobial, and Other Biological Properties of Pompia Juice

“…No anthocyanins were found in the Pompia juice. As previously said, Pompia has been considered a citrus variety belonging to C. limon species [ 17 ], but there are not definitive conclusions on this taxonomy and the most recent studies, based on karyological [ 20 ] and genetic [ 19 ] analyses suggested that Pompia is a cross between sour orange and citron. The provided phenolics characterization of Pompia juice adds elements but cannot solve this puzzle since many molecules identified in Pompia were also found in lemon juice, while some are typical of citron ( Citrus medica L.) [ 29 , 30 ], and some others characterize bergamot [ 13 , 28 ], another species of still uncertain botanical origin, defined as a hybrid between sour orange and lemon [ 15 ].…”

“…nova [ 17 ], previously classified as Citrus x monstruosa [ 18 ], is a particular citron-like tree locally known as “Pompia.” It is an endemic species cultivated in Sardinia, primarily along the north-eastern coast of the Italian island. The tree has an ancient origin [ 19 , 20 ] and its cultivation has recently known a revival because of the use of fruit rind in Sardinian traditional sweets, classified as Slow Food [ 21 ]. For centuries, the local tradition has attributed to Pompia flavedo and its essential oils beneficial properties on health, even though no scientific evidence was available.…”

Development of a Specific Mini-Barcode From Plastome and its Application for Qualitative and Quantitative Identification of Processed Herbal Products Using DNA Metabarcoding Technique: A Case Study on Senna

“…DNA barcoding is a technique for authenticating species using a standard DNA region, aiming to provide rapid, automatable, and cost-effective methods for accurate identification at the species-level. Studies on DNA barcoding have made remarkable progress in species identification ( Naeem et al, 2014 ; Zhang et al, 2016 ; Viglietti et al, 2019 ). Initially used as an identification tool, DNA barcoding is now applied in the industrial quality assurance context to identify herbal products ( Mosa et al, 2018 ; Amritha et al, 2020 ).…”