Heterotrophic Bacteria Play an Important Role in Endemism of Cephalostachyum pingbianense (Hsueh & Y.M. Yang ex Yi et al.) D.Z. Li & H.Q. Yang, 2007, a Full-Year Shooting Woody Bamboo

The previous studies show soil microbes play a key role in the material and nutrient cycles in the forest ecosystem, but little is known about how soil microbes respond to plant distribution, especially in the soil bacterial community in woody bamboo forests. Cephalostachyum pingbianense (Hsueh & Y.M. Yang ex Yi et al.) D.Z. Li & H.Q. Yang, 2007 is known as the only bamboo species producing shoots all year round in natural conditions. Endemic to the Dawei mountain in Yunnan of China, this species is a good case to study how soil bacteria respond to plant endemic distribution. In this work, we assayed the soil chemical properties, enzyme activity, changes in the bacterial community along the distribution range of the C. pingbianense forest. The results showed that soil nutrients at the range edge were nitrogen-rich but phosphorus-deficient, and soil pH value and soil urease activity were significantly lower than that of the central range. No significant difference was detected in soil bacterial diversity, community composition, and function between the central and marginal range of C. pingbianense forest. Notably, the relative abundance of heterotrophy bacteria, such as Variibacter and Acidothermus, in the soil of the C. pingbianense forest was significantly higher than that of the outside range, which may lead to a higher soil organic carbon mineralization rate. These results imply that abundant heterotrophy bacteria were linked to the endemism and full-year shooting in C. pingbianense. Our study is amongst the first cases demonstrating the important role of heterotrophy bacteria in the distribution formation of endemic woody bamboos in special soil habitats, and provides insight into germplasm conservation and forest management in woody bamboos.

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.

A population genetics study of three native Mexican woody bamboo species of Guadua (Poaceae: Bambusoideae: Bambuseae: Guaduinae) using nuclear microsatellite markers

Background: Sporadic flowering contributes significantly to genetic diversity and connectivity among populations. Woody bamboos present sporadic or gregarious flowering patterns with long flowering cycles. In this study, we analyze the genetic diversity of three Guadua species distributed along the Gulf of Mexico slope that have different patterns of flowering. Questions: (1) Are the three Guadua species genetically differentiated? (2) Does the vulnerable species G. inermis have low levels of genetic diversity? (3) What is the relative contribution of geographic and environmental factors to the genetic structure of G. inermis? Species studied: Guadua inermis, G. amplexifolia and G. tuxtlensis Study site and dates: During 2014 and 2015, we collected samples of G. inermis in Puebla and southeastern Mexico, G. amplexifolia in Veracruz and Oaxaca, and G. tuxtlensis in southern Veracruz. Methods: We successfully amplified five of nine SSR markers, and genotyped a total of 155 samples. Results: The three Guadua species were genetically differentiated. For G. inermis, we found high levels of population genetic diversity, which are relatively higher than those of other monocot species. Genetic differentiation was high and three groups were detected: north, central and south. We found a significant association between genetic distances and the maximum temperature of the warmest month, but not with geographic distance. Conclusions: Our study is the first to analyze levels of genetic diversity in Mexican bamboos and confirms their taxonomic identity. G. inermis has a strong genetic structure, even when populations are geographically close.

Diversity, distribution, and classification of Neotropical woody bamboos (Poaceae: Bambusoideae) in the 21st Century

Background: The Neotropical woody bamboos (NWB) comprise a clade native to the Western Hemisphere. Taxonomically the NWB are classified into three subtribes: Arthrostylidiinae, Chusqueinae, and Guaduinae. These woody bamboos are distributed from northern Mexico and the West Indies to south-central Chile and Argentina and from sea level to over 4,000 m in elevation. The most recent comprehensive treatment of the diversity and classification of NWB was published just over 20 years ago, and knowledge of the NWB has greatly increased in the interim. Questions and / or Hypotheses: How much has our knowledge of Neotropical woody bamboo diversity, distribution and classification changed in the last 20 years? Results: The present work reviews the current state of Neotropical woody bamboo taxonomy and provides 1) new morphological keys (in English and Spanish) to and synoptic descriptions of the NWB genera; 2) an updated comprehensive species list; and 3) a biodiversity analysis by country and habitat type. Neotropical woody bamboo diversity presently totals 446 species in 23 genera. In the 21st century, 103 new species and five genera of NWB have been described. Conclusions: The new species and genera described since 2000 have produced an increase in species richness of 29.5 % and a net increase in generic richness of 26.3 %. This new review will be useful for systematists, ecologists, conservation biologists and others working with woody bamboos in the Neotropics.

Un evento de floración en el género Chusquea (Poaceae, Bambusoideae, Bambuseae)

Flowering in woody bamboos is an intriguing phenomenon. Documenting a flowering event provides valuable information about bamboo life cycles. Chusquea argentina is a species endemic to the Andean Patagonian beech forests of Argentina and Chile. We here report a flowering event of C. argentina in northwestern Argentinean Patagonia. We provide a map of the area indicating flowering sites. Photographs showing details of the flowering event are presented. The epidemiological effects of the flowering of C. argentina are taken into consideration.

The phylogenetic position and taxonomic status of the Southeast and South Asian bamboo genera Neohouzeaua and Ochlandra (Poaceae: Bambusoideae)

Among the tropical woody bamboos, the Melocanninae is one of the most clearly recognized subtribes morphologically and has also been consistently well delimited in molecular phylogenetic work. The relationships among those genera in this subtribe, however, have been contentious because of poorly understood generic delimitations, in part due to poor specimen material or insufficiently assessed morphological traits, sometimes exacerbated by poorly accessible provenances. We address the phylogenetic and taxonomic status of two groups which together include the largest number of species in this subtribe: the Neohouzeaua-Schizostachyum complex, distributed from India to South China, Southeast Asia and southwest Pacific, and the endemic Indian genus Ochlandra. Three Neohouzeaua species (including the generic type), 12 Schizostachyum species (including the generic type and several species of uncertain placement), together with five species of Ochlandra and representatives of Cephalostachyum, Melocanna and Pseudostachyum were assessed in a molecular phylogenetic analysis together with members of other well-distinguished subtribes. Members of Neohouzeaua and Schizostachyum align into two main groups that were not completely well-supported statistically but which members possess mostly reflexed culm leaf blades, or mostly erect culm leaf blades. Other characters which provide obvious differences between taxa, such as the number of flowers in a pseudospikelet, fusion of filaments into a staminal tube, and presence of lodicules, were inconsistent between these groups. Neohouzeaua and Schizostachyum cannot be clearly distinguished in either morphological or molecular terms, and thus are united under the latter name, which takes precedence. In reviewing names in Neohouzeaua and their basionyms, several lectotypifications are designated. Three new combinations in Schizostachyum are proposed. On the other hand, Ochlandra forms a distinct clade and its monophyly is demonstrated, supported by clear morphological characters.

Complementary Transcriptome and Proteome Analyses Provide Insight into the Floral Transition in Bamboo (Dendrocalamus latiflorus Munro)

Most woody bamboos bloom only once after long vegetative growth phases and die immediately afterwards. It is difficult, however, to determine the timing of the floral transition, as little information is available on the molecular mechanism of plant maturity in bamboos. To uncover the bamboo floral transition mechanism, its morpho-physiological characteristics, transcriptomes and large-scale quantitative proteomes were investigated in leaves which were collected at different stages during floral transition in a woody bamboo, Dendrocalamus latiflorus. We identified many flowering time-associated genes and the continued increase and decrease genes were screened as flowering biomarker genes (e.g., the MADS14 and bHLH13 genes). These different genes were assigned to specific metabolic pathways by the Kyoto Encyclopedia of Genes and Genomes (KEGG). And the photoperiod pathways depending on the circadian rhythm may play an essential role in the bamboo floral transition. In addition, a total of 721 differently expressed proteins of leaves from the vegetative-to-reproductive stages were identified. Fifty-five genes were specifically differentially expressed at both the transcriptomic and proteomic levels, including genes related to photosynthesis and nucleotide sugar, which may be involved in the floral transition. This work provides insights into bamboo flowers and the management of forest breeding.

Discovery of the first succulent bamboo (Poaceae, Bambusoideae) in a new genus from Laos’ karst areas, with a unique adaptation to seasonal drought

Lush jungle flagship species, woody bamboos (Poaceae–Bambusoideae) are famed for their synchronous flowering as well as the extensive “bamboo forests” some species can form in tropical or temperate environments. In portions of their natural distribution, Bambusoideae members developed various adaptations to seasonality in environmental parameters, such as frost or seasonal drought. A new taxon, Laobambos calcareus, described here, is extremely novel in showing the first documented case of succulence in bamboos, with its ability to seasonally vary the volume of its stem depending on the quantity of water stored. Anatomical studies presented in this paper document this specificity at the cellular level. Though no flowers or fruits are known yet, unique morphological characteristics along with an investigation of its phylogenetic affinities using molecular data show that this new taxon should belong to a new genus herein described.

Epitypification and emended description of Merostachys bifurcata (Poaceae: Bambusoideae: Bambuseae: Arthrostylidiinae)

Merostachys is one of the more species-rich genera of Neotropical woody bamboos. Merostachys includes ca. 55 described species; one of them is M. bifurcata, which is recorded from the Brazilian Atlantic Forest and was described based only on vegetative characters. Morphological analyses carried out in both national and foreign herbaria allowed us to record flowering specimens of this species. We propose here an emended description of M. bifurcata by including data for the reproductive structures, and we propose an epitype for this name. Comments about the taxonomy, habitat, distribution and phenology of this species are provided. A distribution map is provided and an illustration of the main morphological characters of this species is also included.