Plastome phylogeny and lineage diversification of Salicaceae with focus on poplars and willows

Abstract

Phylogenetic relationships and lineage diversification of the family Salicaceae sensu lato (s.l.) remain poorly understood. In this study, we examined phylogenetic relationships between 42 species from six genera based on the complete plastomes. Phylogenetic analyses of 77 protein coding genes of the plastomes produced good resolution of the interrelationships among most sampled species and the recovered clades. Of the sampled genera from the family, Flacourtia was identified as the most basal and the successive clades comprised both Itoa and Poliothyrsis, Idesia, two genera of the Salicaceae sensu stricto (s.s.) (Populus and Salix). Five major subclades were recovered within the Populus clade. These subclades and their interrelationships are largely inconsistent with morphological classifications and molecular phylogeny based on nuclear internal transcribed spacer sequence variations. Two major subclades were identified for the Salix clade. Molecular dating suggested that species diversification of the major subclades in the Populus and Salix clades occurred mainly within the recent Pliocene. In addition, we found that the rpl32 gene was lost and the rps7 gene evolved into a pseudogene multiple times in the sampled genera of the Salicaceae s.l. Compared with previous studies, our results provide a well‐resolved phylogeny from the perspective of the plastomes.

RAD sequencing data reveal a radiation of willow species (SalixL., Salicaceae) in the Hengduan Mountains and adjacent areas

“…So far, molecular studies of the Chamaetia-Vetrix clade either failed to resolve relationships within the Chamaetia - Vetrix clade (Chen et al, 2010; Barkalov & Kozyrenko, 2014; Lauron-Moreau et al, 2015; Wu et al, 2015), or included only a few species of this clade (Zhang et al, 2018a; Zhao et al, 2019). A well-resolved phylogeny of European species did not include Salix species from the HDM and adjacent areas (Wagner et al, 2018).…”

A general model to explain repeated turnovers of sex determination in the Salicaceae

“…The family Salicaceae provides an excellent system to study the drivers of sex chromosome evolution. This family includes two sister genera, Populus and Salix , which are composed exclusively of dioecious species (Peto, 1938; Zhang et al , 2018; Li et al , 2019). Previous studies in multiple Salix species have consistently mapped the sex determination regions (SDRs) to chromosome 15, and proposed a ZW system in which females are the heterogametic sex (Pucholt et al , 2015, 2017; Hou et al , 2015; Chen et al , 2016; Zhou et al , 2018, 2020).…”

The complete choloroplast genome of Flacourtia rukam

“…Furthermore, the location of F. rukam is out of the Idesia polycarpa and is an outgroup to the genera of Salix and Populus with over 90% bootstrap support (Figure 1). The location of other species consisted of the previous study (Zhang et al 2018) of Salicaceae phylogenetic analysis.…”