Abstract
The genus Phoenix (Arecaceae) comprises 14 species distributed from Cape Verde Islands to SE Asia. It includes the economically important species Phoenix dactylifera. The paucity of differential morphological and anatomical useful characters, and interspecific hybridization, make identification of Phoenix species difficult. In this context, the development of reliable DNA markers for species and hybrid identification would be of great utility. Previous studies identified a 12 bp polymorphic chloroplast minisatellite in the trnG (GCC)-trnfM (CAU) spacer, and showed its potential for species identification in Phoenix. In this work, in order to develop an efficient DNA barcode marker for Phoenix, a longer cpDNA region (700 bp) comprising the mentioned minisatellite, and located between the psbZ and trnfM (CAU) genes, was sequenced. One hundred and thirty-six individuals, representing all Phoenix species except P. andamanensis,were analysed. The minisatellite showed 2-7 repetitions of the 12 bp motif, with 1-3 out of seven haplotypes per species. Phoenix reclinata and P. canariensis had species-specific haplotypes. Additional polymorphisms were found in the flanking regions of the minisatellite, including substitutions, indels and homopolymers. All this information allowed us to identify unambiguously eight out of the 13 species, and overall 80% of the individuals sampled. Phoenix rupicola and P. theophrasti had the same haplotype, and so had P. atlantica, P. dactylifera, and P. sylvestris (the “date palm complex” sensu Pintaud et al. 2013). For these species, additional molecular markers will be required for their unambiguous identification. The psbZ-trnfM (CAU) region therefore could be considered as a good basis for the establishment of a DNA barcoding system in Phoenix, and is potentially useful for the identification of the female parent in Phoenix hybrids.
Highlights
Taxonomy and phylogeny of Phoenix L.The genus Phoenix L. (Arecaceae) comprises 14 species (Govaerts and Dransfield 2005), distributed from the E Atlantic (Macaronesia), through Africa, the Mediterranean region, S Asia to islands in the Indian Ocean (Madagascar, Andaman) and the NW Pacific (Taïwan and N Philippines)
The position of Phoenix within the subfamily Coryphoideae has been confirmed by a generic-level phylogenetic analysis of the entire palm family (Arecaceae) that included plastid and nuclear DNA sequences, cpDNA RFLPs and morphological data (Baker et al 2009)
Using one plastid and 16 nuclear microsatellite markers, Pintaud et al (2010) demonstrated that all members of the “datepalm complex” are distinct species. Their data suggested that P. atlantica and P. dactylifera were sister species
Summary
Taxonomy and phylogeny of Phoenix L.The genus Phoenix L. (Arecaceae) comprises 14 species (Govaerts and Dransfield 2005), distributed from the E Atlantic (Macaronesia), through Africa, the Mediterranean region, S Asia to islands in the Indian Ocean (Madagascar, Andaman) and the NW Pacific (Taïwan and N Philippines). The position of Phoenix within the subfamily Coryphoideae has been confirmed by a generic-level phylogenetic analysis of the entire palm family (Arecaceae) that included plastid and nuclear DNA sequences, cpDNA RFLPs and morphological data (Baker et al 2009). Combining sequence data of the chloroplast psbZtrnfM and rpl16-rps loci, Pintaud et al (2013) depicted five distinct phylogenetic lineages within Phoenix (P. loureiroi-acaulis-pusilla, P. roebelenii-paludosa, P. caespitosa, P. reclinata, and P. rupicola-theophrasti-canariensis-dactylifera-atlantica-sylvestris), and restricted the “date palm complex” to P. dactylifera-atlantica-sylvestris. This complex could be distinguished by the presence of a 3-repetitions haplotype of a 20 bp minisatellite motif at the rpl16-rps locus, that was absent in all other species. Phoenix andamanensis was the only taxon not included in their study
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