The Origin of Cultivated Citrus as Inferred from Internal Transcribed Spacer and Chloroplast DNA Sequence and Amplified Fragment Length Polymorphism Fingerprints

By Xiaomeng Li, R. Xie, Zhenhua Lu, Zhiqin Zhou. 2010

85 citations recorded by the source corpus.

Citrus species are among the most important fruit trees in the world and have a long cultivation history. However, until now, the exact genetic origins of cultivated Citrus such as sweet orange (Citrus sinensis), lemon (C. limon), and grapefruit (C. paradisi) have remained unidentified. In the present study, amplified fragment length polymorphism (AFLP) fingerprints, nuclear internal transcribed spacer (ITS), and three plastid DNA regions (psb H- petB, trnL - trnF, and trn S- trnG) of 30 accessions of the cultivated citrus and their putative wild ancestors were analyzed in an attempt to identify their paternal and maternal origins. Molecular phylogenetic trees were constructed based on the AFLP data, and chloroplast DNA and ITS sequences using the genus Poncirus as the outgroup. Our results indicated that bergamot (C. aurantifolia) and lemon were derived from citron (C. medica) and sour orange (C. aurantium), and grapefruit was a hybrid that originated from a cross between pummelo (C. grandis) and sweet orange. Rough lemon (C. limon) was probable as a parent of rangpur lime (C. limonia) and guangxi local lemon (C. limonia). Our data also demonstrated that sweet orange and sour orange were hybrids of mandarin (C. reticulata) and pummelo, while rough lemon was a cross between citron and mandarin. For mexican lime (C. aurantifolia), our molecular data confirmed a species of Papeda to be the female parent and C. medica as the male. These findings provide new information for future study on the taxonomy, evolution, and genetic breeding of Citrus. Citrus species are among the most important fruit crops in the world. They are widely grown in the tropical, subtropical, and borderline subtropical/temperate areas of the world. The genus Citrus was established by Carl Linneaus in 1753 (Swingle and Reece, 1967). Since the establishment of the genus, Citrus has attracted much research interest for more than 250 years (Bayer et al., 2009; Nicolosi et al., 2000; Swingle and Reece, 1967; Tanaka, 1977). The genus Citrus has been variously described as consisting of 1 to 162 species (Malik, 1973; Tanaka, 1977). The most widely accepted taxonomic systems today are those of Swingle (1943) and Tanaka (1977) who recognized 16 and 162 species, respectively. Scora (1975) and Barrett and Rhodes (1976) suggested that there were only three true species within the subgenus Eucitrus of Swingle's system (i.e., C. medica, C. reticulata ,a ndC. grandis). The other genotypes were derived from hybridization between these true species. Citrus has a long history of cultivation—more than 4000 years (Scora, 1988; Webber et al., 1967). However, the huge controversy over the phylogeny of key wild species, and the genetic relationship between the cultivated species and their

Subfields: Cell Biology, Horticulture, Plant Science

View Paper: https://www.semanticscholar.org/paper/e416c2f53f9a7c06c8717a19f092735a0085c49c