Comprehensive molecular and morphological analysis of Brachystemma calycinum and Stellaria ovatifolia in the tribe Alsineae (Caryophyllaceae)

Abstract

Over the course of the recent decade, the composition of Alsineae has been drastically changed by means of molecular phylogeny. However, the genus Brachystemma has not been sampled in any of the previous studies, and its phylogenetic position is still pending. In addition, the related species Stellaria ovatifolia, which has at times been placed in Brachystemma, Schizotechium, or Stellaria, has also not been sampled. Here, nuclear ribosomal internal transcribed spacer (ITS) and four plastid regions (trnL-F, matK, rbcL, rps16) were used to conduct phylogenetic analyses within Caryophyllaceae and the tribe Alsineae. Ancestral characters (petal margin and number of seeds) were reconstructed in the tribe Alsineae based on the phylogenetic results. Our results indicate that Brachystemma is nested in the tribe Alsineae and forms a monophylum with S. ovatifolia, and apically lobed petals and numerous seeds may be the ancestral characters in the tribe Alsineae. Based on our study, Stellaria ovatifolia should be considered within Brachystemma, and Brachystemma is clearly a separate genus and now includes two species.

Phylogenetic analysis and temporal diversification of the tribe Alsineae (Caryophyllaceae) with the description of three new genera, Hesperostellaria, Reniostellaria and Torreyostellaria

“…Within clade II, phylogenetic positions of the two genera Lepyrodiclis and Schizotechium were not resolved or weakly supported in previous studies (Greenberg and Donoghue, 2011;Sadeghian et al, 2015;Zhang et al, 2017;Yao et al, 2021;Arabi et al, 2022), while in our results, phylogenetic positions of the two genera were both well resolved with high supports, especially in analysis of the reduced Alsineae-wide dataset (BSs ≥ 86%, PPs = 1.00; Figure S4). Additionally, the sister relationships between Odontostemma and the Pseudostellaria jamesiana-Stellaria americana lineage, between Pseudostellaria (except P. jamesiana) and Shivparvatia, as well as the sister relationship between the two subclades II-F and II-G, were not resolved or lowly supported in previous studies (Greenberg and Donoghue, 2011;Sadeghian et al, 2015;Zhang et al, 2017;Yao et al, 2021;Arabi et al, 2022;Wang et al, 2023), but were well resolved with high supports in our analyses (Figures 4, S4). On the other hand, the generic relationships within Alsineae obtained here (Figure 4) are highly congruent with those reported in Sharples and Tripp (2019), which was conducted on the basis of reduced representation genomic data but with fewer generic sampling of Alsineae.…”

“…Such as compared with the results of Yao et al. (2021) and Wang et al. (2023) , in which the same set of DNA markers were analyzed but fewer genera of Alsineae were included, phylogenetic positions of multiple genera within the tribe were better resolved and/or obtained higher supports in the present study, including Holosteum , Lepyrodiclis , Moenchia and Shicparvatia ( Figures 4 ; S4 ).…”

“…This viewpoint was also supported in the present study. The improvements gained here in terms of resolution and support of the phylogeny of Alsineae may be attributed to the more extensive generic sampling compared with previous studies, which were conducted on the basis of the same or similar set of DNA markers compared with the present study but with fewer generic sampling of Alsineae (e.g., Greenberg and Donoghue, 2011 ; Zhang et al., 2017 ; Yao et al., 2021 ; Wang et al., 2023 ). Such as compared with the results of Yao et al.…”

“…The improvements gained here in terms of resolution and support of the phylogeny of Alsineae may be attributed to the more extensive generic sampling compared with previous studies, which were conducted on the basis of the same or similar set of DNA markers compared with the present study but with fewer generic sampling of Alsineae (e.g., Greenberg and Donoghue, 2011;Zhang et al, 2017;Yao et al, 2021;Wang et al, 2023). Such as compared with the results of Yao et al (2021) and Wang et al (2023), in which the same set of DNA markers were analyzed but fewer genera of Alsineae were included, phylogenetic positions of multiple genera within the tribe were better resolved and/or obtained higher supports in the present study, including Holosteum, Lepyrodiclis, Moenchia and Shicparvatia (Figures 4; S4). Additionally, including more taxa, even though those with a large proportion of missing data, was also suggested to be important to improve the phylogenetic resolution (Xi et al, 2012;Yao et al, 2019;Yao et al, 2023).…”

“…In the past two decades, molecular phylogenetic studies have changed our understanding on the circumscription of the tribe Alsineae as well as generic delimitation within it ( Fior et al., 2006 ; Harbaugh et al., 2010 ; Greenberg and Donoghue, 2011 ; Dillenberger and Kadereit, 2014 ; Pusalkar and Singh, 2015 ; Sadeghian et al., 2015 ; Zhang et al., 2017 ; Sharples and Tripp, 2019 ; Yao et al., 2021 ; Arabi et al., 2022 ; Wang et al., 2023 ). Bittrich (1993) provided a comprehensive taxonomic treatment of Alsineae and accepted 23 genera in the tribe, viz.…”