Complete plastome sequences of Picea asperata and P. crassifolia and comparative analyses with P. abies and P. morrisonicola

Picea asperata and P. crassifolia have sympatric ranges and are closely related, but the differences between these species at the plastome level are unknown. To better understand the patterns of variation among Picea plastomes, the complete plastomes of P. asperata and P. crassifolia were sequenced. Then, the plastomes were compared with the complete plastomes of P. abies and P. morrisonicola, which are closely and distantly related to the focal species, respectively. We also used these sequences to construct phylogenetic trees to determine the relationships among and between the four species as well as additional taxa from Pinaceae and other gymnosperms. Analysis of our sequencing data allowed us to identify 438 single nucleotide polymorphism (SNPs) point mutation events, 95 indel events, four inversion events, and seven highly variable regions, including six gene spacer regions (psbJ-petA, trnT-psaM, trnS-trnD, trnL-rps4, psaC-ccsA, and rps7-trnL) and one gene (ycf1). The highly variable regions are appropriate targets for future use in the phylogenetic reconstructions of closely related, sympatric species of Picea as well as Pinaceae in general. Key words: Picea crassifolia, Picea asperata, plastome, ycf1, highly variable regions. Le Picea asperata et le P. crassifolia occupent des aires de repartition sympatriques et sont tres proches, mais les differences entre ces especes au niveau de leurs plastomes sont inconnues. Afin de mieux comprendre la variation entre les plastomes du genre Picea, les plastomes complets du P. asperata et du P. crassifolia ont ete sequences. Ensuite, ces plastomes ont ete compares a ceux du P. abies et du P. morrisonicola, lesquelles sont respectivement des especes proches et eloignees des especes a l'etude. Les auteurs ont egalement employe ces sequences pour produire des arbres phylogenetiques visant a determiner les relations entre ces especes ainsi que d'autres taxons au sein des Pinaceae et d'autres gymnospermes. L'analyse des donnees de sequencage a permis d'identifier 438 polymorphismes mononucleotidiques (SNP), 95 indel, quatre inversions et sept regions hypervariables incluant six espaceurs intergeniques (psbJ-petA, trnT-psaM, trnS-trnD, psaC-ccsA et rps7-trnL) et un gene (ycf1). Les regions hypervariables constituent des cibles appropriees pour une future utilisation dans le cadre de reconstructions phylogenetiques au sein d'especes de Picea proches et sympatriques, de meme qu'au sein des Pinaceae. de maniere generale. [Traduit par la Redaction] Mots-cles : Picea crassifolia, Picea asperata, plastome, ycf1, regions hypervariables.
Introduction Spruces (Picea, Pinaceae) are important constituents of forests throughout the Northern Hemisphere. The genus Picea comprises 34 species worldwide, and its distribution and center of differentiation is in Asia [...]