Plastome sequences of two New World bamboos—Arundinaria gigantea and Cryptochloa strictiflora (Poaceae)—extend phylogenomic understanding of Bambusoideae

• Premise of the study: Two New World species of Bambusoideae, Arundinaria gigantea and Crytpochloa strictiflora, were investigated in a phylogenomic context. Complete plastome sequences have been previously determined and analyzed for nine bambusoid species that exclusively represent Old World lineages. The addition of New World species provides more complete information on relationships within Bambusoideae. • Methods: Plastomes from A. gigantea and C. strictiflora were sequenced using Sanger methods. Phylogenomic and divergence estimate analyses were conducted on both species with 23 other Poaceae. • Key Results: Phylogenomic and divergence analyses suggested that A. gigantea diverged from within Arundinarieae between 1.94–3.92 mya and that C. strictiflora diverged as the sister to tropical woody species between 24.83 and 40.22 mya. These results are correlated with modern relative diversities in the two lineages. • Conclusions: The two New World bamboos show unique plastome features accumulated and maintained in biogeographic isolation from Old World taxa. The overall evidence for A. gigantea is consistent with recent dispersal, and that for C. strictiflora is consistent with vicariance.     

Dawyck Botanic Garden: the Heron Wood cryptogamic project

Background: Arundinarieae are a large tribe of temperate woody bamboos for which phylogenetics are poorly understood because of limited taxon sampling and lack of informative characters.

Aims: This study assessed phylogenetic relationships, origins and classification of Arundinarieae.

Methods: DNA sequences (plastid trnL-F; nuclear ITS) were used for parsimony and Bayesian inference including 41 woody bamboo taxa. Divergence dates were estimated using a relaxed Bayesian clock.

Results: Arundinarieae were monophyletic but their molecular divergence was low compared to the tropical Bambuseae. Ancestors of the Arundinarieae lineage were estimated to have diverged from the other bamboos 23 (15–30) million years ago (Mya). However, the Arundinarieae radiation occurred 10 (6–16) Mya compared to 18 (11–25) Mya for the tropical Bambuseae. Some groups could be defined within Arundinarieae, but they do not correspond to recognised subtribes such as Arundinariinae or Shibataeinae.

Conclusions: Arundinarieae are a relatively ancient bambusoid lineage that underwent a rapid radiation in the late Miocene. The radiation coincides with the continental collision of the Indo-Australian and Eurasian Plates. Arundinarieae are distributed primarily in East Asia and the Himalayas to northern Southeast Asia. It is unknown whether they were present in Asia long before their radiation, but we believe recent dispersal is a more likely scenario.     

Identification of putative orthologous genes for the phylogenetic reconstruction of temperate woody bamboos (Poaceae: Bambusoideae)

The temperate woody bamboos (Arundinarieae) are highly diverse in morphology but lack a substantial amount of genetic variation. The taxonomy of this lineage is intractable, and the relationships within the tribe have not been well resolved. Recent studies indicated that this tribe could have a complex evolutionary history. Although phylogenetic studies of the tribe have been carried out, most of these phylogenetic reconstructions were based on plastid data, which provide lower phylogenetic resolution compared with nuclear data. In this study, we intended to identify a set of desirable nuclear genes for resolving the phylogeny of the temperate woody bamboos. Using two different methodologies, we identified 209 and 916 genes, respectively, as putative single copy orthologous genes. A total of 112 genes was successfully amplified and sequenced by next‐generation sequencing technologies in five species sampled from the tribe. As most of the genes exhibited intra‐individual allele heterozygotes, we investigated phylogenetic utility by reconstructing the phylogeny based on individual genes. Discordance among gene trees was observed and, to resolve the conflict, we performed a range of analyses using BUCKy and HybTree. While caution should be taken when inferring a phylogeny from multiple conflicting genes, our analysis indicated that 74 of the 112 investigated genes are potential markers for resolving the phylogeny of the temperate woody bamboos.     

Two new species of Yushania (Poaceae: Bambusoideae) from South China,with a taxonomic revision of related species

Two new species of Yushania (Poaceae, Bambusoideae, Arundinarieae) are described and illustrated from Hunan, China. Yushania longshanensis D.Z. Li & X.Y. Ye is distinguished from related species (Y. confusa, Y. angustifolia and Y. pachyclada) by having a thinner culm (0.2–0.3 cm in diameter), glabrous sheath scar, no oral setae, a large glabrous leaf blade (10–20 × 0.9–1.3 cm) and 3–4 pairs of secondary veins. Yushania stoloniforma D.Z. Li & X.Y. Ye has a distinctive scrambling habit, which differs from its putative close allies. Both of these two new species have a solitary branch at the basal nodes and can be assigned to Yushania sect. Yushania based on morphological features. Additionally, we treated Yushania gigantea T.P. Yi & L. Yang as a new synonym of Y. elevata T.P. Yi and renamed Y. microphylla T.P. Yi & L. Yang as Y. weiningensis D.Z. Li & X.Y. Ye.