Multi-locus plastid phylogenetic biogeography supports the Asian hypothesis of the temperate woody bamboos (Poaceae: Bambusoideae).

In this paper we investigate the biogeography of the temperate woody bamboos (Arundinarieae) using a densely-sampled phylogenetic tree of Bambusoideae based on six plastid DNA loci, which corroborates the previously discovered 12 lineages (I-XII) and places Kuruna as sister to the Chimonocalamus clade. Biogeographic analyses revealed that the Arundinarieae diversified from an estimated 12 to 14Mya, and this was followed by rapid radiation within the lineages, particularly lineages IV, V and VI, starting from c. 7-8Mya. It is suggested that the late Miocene intensification of East Asian monsoon may have contributed to this burst of diversification. The possibilities of the extant Sri Lankan and African temperate bamboo lineages representing 'basal elements' could be excluded, indicating that there is no evidence to support the Indian or African route for migration of temperate bamboo ancestors to Asia. Radiations from eastern Asia to Africa, Sri Lanka, and to North America all are likely to have occurred during the Pliocene, to form the disjunct distribution of Arundinarieae we observe today. The two African lineages are inferred as being derived independently from Asian ancestors, either by overland migrations or long-distance dispersals. Beringian migration may explain the eastern Asian-eastern North American disjunction.

Biogeography and phylogenomics of New World Bambusoideae (Poaceae), revisited.

UNLABELLED: • PREMISE OF THE STUDY: New World Bambusoideae have only recently been studied in a phylogenomic context. Plastome sequences were determined and analyzed from Arundinaria appalachiana, A. tecta, and Olyra latifolia, to refine our knowledge of their evolution and historical biogeography. A correction is noted regarding an error in an earlier report on the biogeography of Cryptochloa• METHODS: Single-end DNA libraries were prepared and sequenced on the Illumina platform. Complete plastomes were assembled and analyzed with 13 other Poaceae.• KEY RESULTS: Complete sampling in Arundinaria and an additional species of Olyreae gave a more detailed picture of their evolution/historical biogeography. Phylogenomic analyses indicated that the first major divergence in Arundinaria occurred around 2.3 to 3.2 mya and that Arundinaria tecta and A appalachiana diverged from their common ancestor around 0.57 to 0.82 mya. Estimates of the divergence of Olyra latifolia from Cryptochloa strictiflora ranged from 14.6 to 20.7 mya. The age of the stem node of Olyreae ranged from an estimated 26.9 to 38.2 mya.• CONCLUSIONS: Estimates of divergences in Arundinaria can be correlated with paleoclimatic events including an early Pliocene warming, subsequent cooling, and North American glaciations. Discriminating between alternate evolutionary/biogeographic scenarios in Olyreae is challenging.

Chimonobambusafarcta (Poaceae, Bambusoideae), a new species from western Guangxi, China with taxonomic notes on C.pubescens and C.luzhiensis.

Chimonobambusafarcta, a new species of temperate woody bamboos from western Guangxi, China is described and illustrated. The new species is similar to C.pubescens in the solid internodes of culms, but differs in having taller culm to 7 m with longer verrucose internodes to 23.5 cm and intranodes to 4 mm, intranode usually with a ring of 7-9 root thorns below mid-culm, abaxially brown or brown-purple verrucose-setose culm leaf sheaths with indistinct transverse veins, conspicuously developed culm leaf blades to 3.2 cm long, longer foliage leaf sheaths to 5.2 cm, larger and broader foliage leaf blades to 22 × 1.4 cm. It also somewhat resembles C.convoluta, but can be easily distinguished by having solid internodes and longer intranode 2-4 mm, very prominent nodes with supranodal ridge obviously more elevated than sheath scar, usually persistent and sometimes brownish striate culm leaf sheaths, longer culm leaf blades to 3.2 cm, and abaxially glabrous foliage leaf sheaths. Based on the morphological characteristics, this new species is assigned to C.sect.Chimonobambusa. The character description of C.pubescens are revised for its culm to 2.1 m tall, 1.1 cm in diameter and glabrous foliage leaf blades. The systematic position of C.luzhiensis is discussed, and this species is proposed as a member of C.sect.Chimonobambusa.

Gelidocalamusalbozonatus (Poaceae, Bambusoideae), a new species from the southeast of Chongqing, China, and analysis of the morphological diversity in the core group of Gelidocalamus.

Gelidocalamusalbozonatus W. G. Zhang, S. R. Yi & Y. L. Li, a new species of Gelidocalamus, collected from Pengshui County of Chongqing City in China, was described and illustrated herein. In this study, key morphological characters were compared between the new species and other eight "gelido-" members of Gelidocalamus. By using scanning electron microscopy (SEM), its leaf epidermal characters were observed in comparison with those of another three Gelidocalamus representatives. Our results show that the new taxon has the typical characteristics of the genus Gelidocalamus, both macromorphologically and micromorphologically. Moreover, it was most similar to G.tessellatus, but differed by a ring of white tomenta below per node, culm sheath base with densely purple verrucous setae and foliage leaf blades mesophyll.

The complete chloroplast genome of Pseudosasa usawae (Poaceae: Bambusoideae: Arundinarieae) in Taiwan.

Pseudosasa usawae is an endemic species in Taiwan, and grows at an altitude of 600-1200 m. In this study, we fully characterized the complete chloroplast genome of P. usawae. The complete chloroplast sequence was 139,660 bp, including large single-copy (LSC), small single-copy (SSC), and a pair of invert repeats (IR) region of 83,271, 12,803, and 21,793 bp. Besides, the plastid genome comprised a total of 129 genes, including protein-coding, tRNA, and rRNA genes as 83, 38, and 8 genes. Phylogenetic analysis reveals that P. usawae is closely associated with Phyllostachys genus clade, sister to the lineage of Phyllostachys.

Histological, metabolomic and transcriptomic analyses reveal mechanisms of cold acclimation of the Moso bamboo (Phyllostachys edulis) leaf.

The Moso bamboo (Phyllostachys edulis) leaf copes well with cold winters in southeastern China. However, until now, there has been almost no research on its adaptation mechanisms to cold weather. Herein, we found that the Moso bamboo leaf has evolved several anatomical structures that may play a role in enhancing its cold tolerance. These structures include fewer fusiform cells, smaller bulliform cells, lower stomata density and many more trichomes, as well as lower relative water content than in the leaf of a cold-sensitive bamboo species, Bambusa ventricosa. Untargeted metabolomic analysis revealed that the winter leaf of Moso bamboo had 10- to 1000-fold higher stress-resistant metabolites such as glutathione, trehalose and ascorbic acid than the leaf of B. ventricosa on both warm and cold days. In contrast to the leaves that grew on a warm day, some metabolites such as glutathione and trehalose increased dramatically in the leaves of Moso bamboo that grew on a cold day. However, they unexpectedly decreased in the leaf of B. ventricosa growing at cold temperatures. Transcriptome analysis revealed a cold stress response network that includes trehalose, glutathione, flavonoid metabolism, DNA repair, reactive oxygen species degradation, stress-associated genes and abiotic stress-related plant hormones such as jasmonic acid, abscisic acid and ethylene. The potential mediator transcription factors, such as EREBP, HSF, MYB, NAC and WRYK, were also significantly upregulated in Moso bamboo leaves growing at cold temperatures. Interestingly, many newly identified genes were involved in the transcriptome of the winter leaf of the Moso bamboo. Most of these new genes have not even been annotated yet. The above results indicate that the Moso bamboo leaf has evolved special histological structures, metabolic pathways and a cold stress-tolerant transcriptome to adapt to the cold weather in its distribution areas.

The complete chloroplast genome and phylogenetic position of Thamnocalamus unispiculatus (Poaceae: Bambusoideae: Arundinarieae).

Thamnocalamus unispiculatus T.P.Yi & J.Y.Shi 2007 is an important bamboo species with significant ecological and economic value. This study presents the complete chloroplast genome sequence of T. unispiculatus. The sequence was 139,726 bp in length and exhibited a typical quadripartite structure, containing four regions: large single copy regions (LSC, 83,283 bp), small single copy regions (SSC, 12,851 bp) and a pair of inverted repeats (IRs, 21,726 bp). A total of 130 genes were annotated, including 86 protein-coding genes, 36 transfer RNA genes, and eight ribosomal RNA genes. Phylogenetic analysis indicated that T. unispiculatus and T. spathiflorus are sister species, supporting the conclusion that Thamnocalamus is a monophyletic group. The chloroplast genome of T. unispiculatus promotes the protection and exploration of biodiversity, phylogenetic relationships, and genetic research in Bambusoideae.

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.

Gelidocalamus fengkaiensis (Poaceae: Bambusoideae), a new bamboo species from Guangdong, China, with an analysis of branch development in relation to flowering.

BACKGROUND: Bamboos, widely distributed in temperate and tropical Asia, Africa and America, refer to a group of special plants in Poaceae, Bambusoideae. China is rich in bamboo species. However, due to a long flowering cycle, the flowering habit and the flowering structure of many bamboo species are still not well understood. Here, we report a new bamboo species from Guangdong, China and an analysis of its interesting branch development in relation to flowering. RESULTS: This species is similar to G. stellatus, the type species, but differs in the characteristics of its lemma and palea, mid-culm branch complement, and culm-sheath ligules. The initial branches at a culm node do not apically develop flowering structures during a flowering episode; instead, these form on what appears to be specialized flowering branches. CONCLUSIONS: The results of morphological comparison support the recognition of Gelidocalamus fengkaiensis as a new species. And during a flowering episode, two branch types ('foliage branch' and 'flowering branch') can be distinguished in this species.

Integrated Genomic Analyses From Low-Depth Sequencing Help Resolve Phylogenetic Incongruence in the Bamboos (Poaceae: Bambusoideae).

The bamboos (Bambusoideae, Poaceae) comprise a major grass lineage with a complex evolutionary history involving ancient hybridization and allopolyploidy. About 1700 described species are classified into three tribes, Olyreae (herbaceous bamboos), Bambuseae (tropical woody bamboos), and Arundinarieae (temperate woody bamboos). Nuclear analyses strongly support monophyly of the woody tribes, whereas plastome analyses strongly support paraphyly, with Bambuseae sister to Olyreae. Our objectives were to clarify the origin(s) of the woody bamboo tribes and resolve the nuclear vs. plastid conflict using genomic tools. For the first time, plastid and nuclear genomic information from the same bamboo species were combined in a single study. We sampled 51 species of bamboos representing the three tribes, estimated their genome sizes and generated low-depth sample sequence data, from which plastomes were assembled and nuclear repeats were analyzed. The distribution of repeat families was found to agree with nuclear gene phylogenies, but also provides novel insights into nuclear evolutionary history. We infer two early, independent hybridization events, one between an Olyreae ancestor and a woody ancestor giving rise to the two Bambuseae lineages, and another between two woody ancestors giving rise to the Arundinarieae. Retention of the Olyreae plastome associated with differential dominance of nuclear genomes and subsequent diploidization in some lineages explains the paraphyly observed in plastome phylogenetic estimations. We confirm ancient hybridization and allopolyploidy in the origins of the extant woody bamboo lineages and propose biased fractionation and diploidization as important factors in their evolution.

Khoonmengia honbaensis, a new genus and species of temperate bamboo (Poaceae, Bambusoideae) from central-southern Vietnam.

A new genus of Arundinarieae, Khoonmengia, is established to accommodate a unique new bamboo species, K. honbaensis, from central-southern Vietnam. The morphological features, habitats and distribution of Khoonmengia and related genera, i.e. Ampelocalamus and Hsuehochloa, are compared. The characters of its scrambling habit, internodes with brownish green dots, conspicuous nodes swollen at one side, elliptic buds wholly sunken into culm, extravaginal branching pattern, mid-culm branch complement with one central dominant branch elongating to reiterate the culm accompanied by several lateral slender branches, swollen culm sheath base with a distinctive zone of transverse wrinkles, synflorescence composed of only one spikelet, single or several to many synflorescences arranged into a raceme or panicle terminal on leafy branches, purple anthers and nut-like caryopsis with hardened pericarp and loosely adherent lemma and palea distinguish K. honbaensis from morphologically similar taxa. In order to investigate the phylogenetic position of this unknown bamboo, molecular phylogenetic analyses based on the nuclear gene GBSSI were also conducted, and the results proved that K. honbaensis is definitely a member of Arundinarieae with an isolated position, which also indicated that this species could not be assigned to any of the already described genera and supported the establishment of the new genus.

The complete chloroplast genome of Phyllostachys glauca (Bambusoideae), a dominant bamboo species in limestone mountains endemic to China.

Phyllostachys glauca is a dominant species in limestone mountains endemic to China. Here, we characterized its complete chloroplast genome. It is a circular DNA molecule of 139,689 bp in length, including a pair of 21,798 bp inverted repeats (IRs), a 12,872 bp small single-copy (SSC) region and an 83221 bp large single-copy (LSC) region. The total GC content of P. glauca chloroplast genome was 38.9%, and it encodes a total of 137 functional genes, including 89 protein-coding genes, 40 tRNA genes, and 8 rRNA genes. The phylogenetic analysis shows that P. glauca is highly clustered in the Phyllostachys clade (V), sister to the lineage of P. nigra var. henonis + P. sulphurea.

The complete chloroplast genome sequence of Acidosasa gigantea (Bambusoideae: Arundinarieae): an ornamental bamboo species endemic to China.

We, at first, fully characterized the complete chloroplast genome of the woody bamboo Acidosasa gigantea using genome skimming and focused on comparative analyses among Acidosasa and Indosasa. This newly sequenced chloroplast genome (GenBank NO. MN917206) is a typical circular structure with 139,711 bp in length and comprises of an 83,295 bp large single-copy (LSC) region, a 12,824 bp small single-copy (SSC) region, and a pair of 21,796 bp inverted repeats (IRs). The GC content of A. gigantea is 38.9% and the sequences contained 132 unique genes were successfully annotated, including 39 tRNA genes, 8 rRNA genes, and 85 protein-coding genes. Phylogenetic analysis shows that A. gigantea is highly clustered in the Arundinaria clade (clade VI) of Arundinarieae, a sister of the clade of Acidosasa purpurea and was not clustered on the same branch as Indosasa sinica. Therefore, it is more accurate to classify A. gigantea into Acidosasa.

Two plastomes of Phyllostachys and reconstruction of phylogenic relationship amongst selected Phyllostachys species using genome skimming.

The genus Phyllostachys is economically important; however, only a small amount of complete plastid genomes have been reported to date. Here, we characterized two complete chloroplast genomes of Phyllostachys using genome skimming. The chloroplast genomes of Phyllostachys reticulata and Phyllostachys edulis 'Pachyloen' were 136,689 bp and 139,678 bp in length, respectively, and their GC contents were 38.8% and 38.9%, respectively. The sequences of each species contained 132 unique genes, including 39 tRNA, eight rRNA, and 85 protein-coding genes. Phylogenetic analysis shows that all selected Phyllostachys species were grouped into one well-supported clade in the Phyllostachys clade (V) of Arundinarieae. Moreover, in terms of chloroplast genome size, structure, and composition, P. edulis 'Pachyloen' is identical to P. edulis, further indicating the affinity between them.

Gelidocalamus xunwuensis (Poaceae, Bambusoideae), a new species from southeastern Jiangxi, China.

Gelidocalamus xunwuensis W.G.Zhang & G.Y.Yang, a new species collected from Xunwu County of Jiangxi Province in China, is described and illustrated. The new species is similar to G. stellatus in the habit, but differs by internodes sparsely hairy with granuliferous warts, culm sheath stiffly hairy, culm sheath blade broadly lanceolate to narrowly triangular, each node with a ring of appressed trichomes below, foliage leaves broadly lanceolate to narrowly oblong, and new shoots occurring in late October.

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.

Bergbambos and Oldeania, new genera of African bamboos (Poaceae, Bambusoideae).

Two new monotypic genera, Bergbambos and Oldeania are described for African temperate bamboo species in the tribe Arundinarieae, after a comparison of their morphological characteristics with those of similar species from Asia. Morphological differences are supported by their isolated geographical distributions. Molecular evidence does not support the inclusion of these species in related Asian genera, recognising them instead as distinct lineages. New combinations Bergbambos tessellata and Oldeania alpina are made.