Flowering cycles of woody bamboos native to southern South America

Phylogenomic and morphological evidence supports the reinstatement of the bamboo genus Clavinodum from Oligostachyum (Poaceae: Bambusoideae)

One of the most intractable problems in bamboo systematics concerns the three-branched bamboos of tribe Arundinarieae (Poaceae: Bambusoideae), which are collectively characterized by having three branches per mid-culm node. Previous phylogenetic studies based on double-digest restriction-site associated DNA sequencing (ddRAD-seq) data confirmed that Oligostachyum, a member of this group, is non-monophyletic, and in particular that Oligostachyum oedogonatum is a problematic species deserving further attention, as it appears to be morphologically and phylogenetically distinct from the other three-branched bamboos. Here we aim to define and confirm the phylogenetic position of O. oedogonatum, by including representatives from across its geographic range. We also provide new insights into the overall phylogeny of the three-branched bamboos and closely related genera, using multiple phylogenomic datasets. While a plastid genome-based tree is very poorly supported, phylogenies inferred using two sets of conserved nuclear genes and single nucleotide polymorphism (SNP) data yield generally well-supported and congruent topologies using coalescent-based approaches. The tree inferred from the largest concatenated gene set is the most dissimilar to other inferences. The nuclear-based data sets all recover a major clade that includes all of the three-branched bamboos and four other genera, which can be distinguished from related taxa due to their possession of three stigmas per floret and leptomorph rhizomes. Notably, eight O. oedogonatum samples form a clade that is distantly related to other members of Oligostachyum, including the type species of the genus (Oligostachyum sulcatum). Population genetic approaches and multi-species coalescent-based analysis of the nuclear data sets imply that seven of these populations can be treated as a single species, O. oedogonatum, but that one population from Jinggangshan is likely an intergeneric hybrid between O. oedogonatum and Pleioblastus. Morphologically, O. oedogonatum differs from all other three-branched bamboos, in having strongly asymmetrically swollen supra-nodal ridges, a laterally compressed spikelet, and rachilla segments that disarticulate readily below fertile florets. Because of its morphological distinctiveness and molecular phylogenetic position, we propose that this taxon should be reinstated as Clavinodum oedogonatum. We provide a new description for this monotypic genus here.

Advances in bamboo genomics: Growth and development, stress tolerance, and genetic engineering

Bamboo is a fast-growing and ecologically significant plant with immense economic value due to its applications in construction, textiles, and bioenergy. However, research on bamboo has been hindered by its long vegetative period, unpredictable flowering cycles, and challenges in genetic transformation. Recent developments in advanced sequencing and genetic engineering technologies have provided new insights into bamboo's evolutionary history, developmental biology, and stress resilience, paving the way for improved conservation and sustainable utilization. This review synthesizes the latest findings on bamboo's genomics, biotechnology, and the molecular mechanisms governing its growth, development, and stress response. Key genes and regulatory pathways controlling its rapid growth, internode elongation, rhizome development, culm lignification, flowering, and abiotic stress responses have been identified through multi-omics and functional studies. Complex interactions among transcription factors, epigenetic regulators, and functionally important genes shape bamboo's unique growth characteristics. Moreover, progress in genetic engineering techniques, including clustered regularly interspaced short palindromic repeats-based genome editing, has opened new avenues for targeted genetic improvements. However, technical challenges, particularly the complexity of polyploid bamboo genomes and inefficient regeneration systems, remain significant barriers to functional studies and large-scale breeding efforts. By integrating recent genomic discoveries with advancements in biotechnology, this review proposes potential strategies to overcome existing technological limitations and to accelerate the development of improved bamboo varieties. Continued efforts in multi-omics research, gene-editing applications, and sustainable cultivation practices will be essential for harnessing bamboo as a resilient and renewable resource for the future. The review presented here not only deepens our understanding of bamboo's genetic architecture but also provides a foundation for future research aimed at optimizing its ecological and industrial potential.

Ecological Relationships Between Woody Species Diversity and Propagation Strategies of Aulonemia queko

This study explores how floristic composition, diversity, and woody vegetation structure vary across floristic zones in Andean montane forests under the dominance of Aulonemia queko Goudot (Poaceae, Bambusoideae) dominance. As a culturally and ecologically significant non-timber forest product, A. queko plays a key role in shaping plant communities and requires effective propagation strategies for sustainable management. Significant differences in floristic composition were observed among zones, with indicator species identified in the lower and upper zones. However, despite environmental variability, species richness and structural attributes remained stable across the elevation gradient, suggesting resilience in woody plant communities. A. queko density was highest in the upper zone, while its basal area peaked in the lower and middle zones, probably shaping floristic composition through competitive interactions and habitat modification. Propagation experiments revealed that shoots with rhizomes exhibited higher survival and growth, particularly in mulch substrates with 1000 ppm indole-3-butyric acid (IBA), highlighting the importance of shoot type, substrate, and hormone dose. These findings suggest that A. queko is a structuring species and a potential restoration target. However, its dominance may alter forest composition, requiring adaptive management strategies that balance its ecological role with conservation and sustainable use, ensuring biodiversity and ecosystem resilience.

Mysterious Bamboo flowering phenomenon: A literature review and new perspectives

Bamboo, a globally distributed non-timber forest resource, plays a critical role in local ecosystems and economies. Despite its significance, the understanding of bamboo's long and unpredictable flowering cycles remains limited. Our bibliometric analysis of bamboo flowering-related literature from the Web of Science database reveals an initial focus on regeneration studies, with a recent trend shifting towards microscopic and molecular perspectives. Furthermore, our narrative review emphasizes the importance of considering factors such as the proportion of flowering culms and the duration of flowering in classifying bamboo flowering phenomena. While numerous studies have endorsed the predator saturation hypothesis as a suitable explanation for the synchronicity of bamboo flowering, no existing theory explains bamboo's prolonged flowering cycles. We propose a new natural selection hypothesis as a potential explanation for these extraordinary cycles, underscoring the need for further research in this area. Despite the substantial volume of data accumulated on bamboo flowering, these resources have not been fully exploited in recent research. Future studies would benefit from more comprehensive data collection methods, encompassing field observations, satellite remote sensing data, and omics data. The convergence of traditional ecological studies with molecular techniques may pave the way for significant advancements in bamboo flowering research.

A comparative full-length transcriptomic resource provides insight into the perennial monocarpic mass flowering

Perennial monocarpic mass flowering represents as a key developmental innovation in flowering time diversity in several biological and economical essential families, such as the woody bamboos and the shrubby Strobilanthes. However, molecular and genetic mechanisms underlying this important biodiversity remain poorly investigated. Here, we generated a full-length transcriptome resource incorporated into the BlueOmics database (http://blueomics.iflora.cn) for two Strobilanthes species, which feature contrasting flowering time behaviors. Using about 112 and 104 Gb Iso-seq reads together with ~185 and ~75 Gb strand-specific RNA seq data, we annotated 80 971 and 79 985 non-redundant full-length transcripts for the perennial polycarpic Strobilanthes tetrasperma and the perennial monocarpic Strobilanthes biocullata, respectively. In S. tetrasperma, we identified 8794 transcripts showing spatiotemporal expression in nine tissues. In leaves and shoot apical meristems at two developmental stages, 977 and 1121 transcripts were differentially accumulated in S. tetrasperma and S. biocullata, respectively. Interestingly, among the 33 transcription factors showing differential expression in S. tetrasperma but without differential expression in S. biocullata, three were involved potentially in the photoperiod and circadian-clock pathway of flowering time regulation (FAR1 RELATED SEQUENCE 12, FRS12; NUCLEAR FACTOR Y A1, NFYA1; PSEUDO-RESPONSE REGULATOR 5, PRR5), hence provides an important clue in deciphering the flowering diversity mechanisms. Our data serve as a key resource for further dissection of molecular and genetic mechanisms underpinning key biological innovations, here, the perennial monocarpic mass flowering.

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.

The SOC1-like gene BoMADS50 is associated with the flowering of Bambusa oldhamii

Bamboo is known for its edible shoots and beautiful texture and has considerable economic and ornamental value. Unique among traditional flowering plants, many bamboo plants undergo extensive synchronized flowering followed by large-scale death, seriously affecting the productivity and application of bamboo forests. To date, the molecular mechanism of bamboo flowering characteristics has remained unknown. In this study, a SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1)-like gene, BoMADS50, was identified from Bambusa oldhamii. BoMADS50 was highly expressed in mature leaves and the floral primordium formation period during B. oldhamii flowering and overexpression of BoMADS50 caused early flowering in transgenic rice. Moreover, BoMADS50 could interact with APETALA1/FRUITFULL (AP1/FUL)-like proteins (BoMADS14-1/2, BoMADS15-1/2) in vivo, and the expression of BoMADS50 was significantly promoted by BoMADS14-1, further indicating a synergistic effect between BoMADS50 and BoAP1/FUL-like proteins in regulating B. oldhamii flowering. We also identified four additional transcripts of BoMADS50 (BoMADS50-1/2/3/4) with different nucleotide variations. Although the protein-CDS were polymorphic, they had flowering activation functions similar to those of BoMADS50. Yeast one-hybrid and transient expression assays subsequently showed that both BoMADS50 and BoMADS50-1 bind to the promoter fragment of itself and the SHORT VEGETATIVE PHASE (SVP)-like gene BoSVP, but only BoMADS50-1 can positively induce their transcription. Therefore, nucleotide variations likely endow BoMADS50-1 with strong regulatory activity. Thus, BoMADS50 and BoMADS50-1/2/3/4 are probably important positive flowering regulators in B. oldhamii. Moreover, the functional conservatism and specificity of BoMADS50 and BoMADS50-1 might be related to the synchronized and sporadic flowering characteristics of B. oldhamii.

Identification and characterization of SSR markers of Guadua chacoensis (Rojas) Londoño & P.M. Peterson and transferability to other bamboo species

The aim of this study was to develop simple sequence repeat (SSR) markers for genetic studies on G. chacoensis, as well as to evaluate their transferability to other bamboo species. Genomic DNA was isolated from G. chacoensis and its partial sequencing was used to find SSR loci. The obtained sequencing data were de novo assembled using the software CLC Genomics Workbench^® 8.0v. The SSR loci primers were identified and designed with the software SSRLocator. The selected markers were validated using 56 plants sampled in seven populations from southern Brazil. The markers with potential polymorphism were selected and fluorescently labeled for characterization by capillary electrophoresis. In total, 92 SSR loci were found in G. chacoensis contigs. Suitable primers were designed for 70 SSR loci, and the remaining 22 SSR loci did not have sequences for primer development. Out of 35 selected SSR markers, after PCR optimization, 10 with high polymorphism potential were characterized. These loci can be used in genetic analyses of G. chacoensis and all of them were successfully transferred to other bamboo species. Non-polymorphic loci require further tests with additional plants, from different populations, to identify possibilities of their use.

The Bamboo Flowering Cycle Sheds Light on Flowering Diversity

Bamboo is a perennial flowering plant with a distinctive life cycle: many bamboo species remain in the vegetative phase for decades, followed by mass synchronous flowering and subsequent death. The phenomenon of bamboo flowering is not fully understood, but its periodicity is a major research focus. Here, we collected information on bamboo flowering events by investigating historical documents and field studies at the Bamboo Research Institute of Nanjing Forestry University. We compiled information on more than 630 flowering events, 124 of which accurately recorded the flowering cycle time. We summarized the specific flowering cycles of 85 bamboo species, as well as four kinds of bamboo flowering habits in detail. We present a theory of the bamboo flowering cycle and discuss the reasons for the observed variations in bamboo flowering. This review also introduces two mechanisms by which bamboo forests are rejuvenated after flowering and explains the flowering phenomena of bamboo forests using the bamboo flowering cycle theory. Finally, we present suggestions for forest management strategies. Bamboo flowering is a normal physiological phenomenon, even though it has unique elements compared with flowering in other plants. The results presented here provide valuable reference material for understanding bamboo flowering and its periodicity.

Flowering of Guadua trinii (Poaceae, Bambusoideae, Bambuseae)

Abstract Flowering in bamboo is an unusual event. Documenting flowering individuals or populations provides valuable information about bamboo life cycles. Guadua trinii is endemic to northeastern Argentina, southern Brazil, Paraguay and Uruguay. We here report the flowering of this species in native and cultivated stands in Argentina and confirm its flowering cycle to be of 30-33 years.

The Uses of Herbaria in Botanical Research. A Review Based on Evidence From Argentina

Botanists, a section of the broad universe of researchers in Biology, are intensive users of herbaria. Presumably, all botanists use herbaria, with greater or lesser frequency and intensity, in the development of their research. In this article, we will try to prove this statement. For this purpose, an institutional history of Botany and herbaria in Argentina is presented. This study will also show that there are other fields of knowledge in which the herbarium has a role as an input, or data source, for research (e.g. agronomy, ethnobotany, medicine). On the other hand, it will be demonstrated that, in addition to the uses of the herbarium in basic science, this institution has a crucial role in the knowledge and preservation of biodiversity, and in the improvement of species for commercial use.

A method to implement continuous characters in digital identification keys that estimates the probability of an annotation

PREMISE

Species identification is vital to many disciplines. Digital technology has improved identification tools, but the direct use of characters with continuous states has yet to be fully realized. To achieve full use of continuous characters for identification, I propose a classifier that calculates a posterior probability (degree of belief) in possible name assignments and an estimate of the relative evidence for the candidate annotations.

METHODS

A model for a species is defined using continuous morphological characters, and an algorithm for identification with a naive Bayesian classifier, using the model, is presented. A method of estimating the strength of evidence for candidate species is also described.

RESULTS

The proposed method is applied in two example identifications: native vs. invasive Myriophyllum in North America and vegetative Rhipidocladum bamboos in Mexico. In each instance, the new method provides a probability and estimate of the strength of the probability to enhance the name assignment in situations where taxa are difficult to differentiate using discrete character states.

DISCUSSION

Naive Bayesian classifiers take advantage of the predictive information inherent in continuous morphological characters. Application of this methodology to plant taxonomy advances our ability to leverage digital technology for improved interactive taxonomic identifications.

Seed Set and Natural Regeneration of Dendrocalamus membranaceus Munro after Mass and Sporadic Flowering in Yunnan, China

The flowering periods of woody bamboos, seed set, natural regeneration and death after flowering have been rarely observed and evaluated in the field. Dendrocalamus membranaceus Munro, a tropical woody bamboo mainly distributed in the Yunnan, displayed both sporadic as well as gregarious (mass) flowering and fruited from 2006 to 2013 following severe droughts. The aim of this study is to examine potential differences in seed set and natural regeneration between the two flowering patterns in natural D. membranaceus forests. We investigated and analyzed seed set, seed germination, seedling growth and mortality in both mass and sporadic flowering populations. Observations were made over a period of three years to record changes in bamboo seedling density, height and culm diameter. We observed a low natural seed set ranging from 1.76% to 7.49%, and a relatively high seed germination rate in the nursery from 59.6% to 71.0% for both types of flowering populations. Seeds germinated in 5–7 days after sowing and the germination period lasted 10–15 days. Seed set and germination rates in mass-flowering populations were significantly higher than those of sporadically flowering stands. The seedlings within sporadically flowering populations died within two years. In comparison, seedling mortality in the mass flowering population increased over two periods of observation from 64.92% to 98.89%, yet there was good seedling establishment left over, which showed mean height and mean culm diameter increasing by 1053.25% and 410.71%, respectively, in the second year of observations, and 137.10%, and 217.48%, respectively, in the third year. There are significant differences in seed set, natural regeneration ability and sustainability of bamboo populations between the mass flowering and sporadically flowering populations of D. membranaceus. Sporadic flowering populations failed to produce effective regeneration, while mass flowering populations were able to regenerate successfully. This study provides useful insights for conservation and natural forest management of D. membranaceus. We consider the merits of introducing other genetic provenances towards long-term maintenance of the stand features at sporadically flowering sites; meanwhile, the most economic option for mass flowering stands is to allow natural regeneration to take place through protecting such sites from further disturbance.

Evolution of periodicity in periodical cicadas

Periodical cicadas (Magicicada spp.) in the USA are famous for their unique prime-numbered life cycles of 13 and 17 years and their nearly perfectly synchronized mass emergences. Because almost all known species of cicada are non-periodical, periodicity is assumed to be a derived state. A leading hypothesis for the evolution of periodicity in Magicicada implicates the decline in average temperature during glacial periods. During the evolution of periodicity, the determinant of maturation in ancestral cicadas is hypothesized to have switched from size dependence to time (period) dependence. The selection for the prime-numbered cycles should have taken place only after the fixation of periodicity. Here, we build an individual-based model of cicadas under conditions of climatic cooling to explore the fixation of periodicity. In our model, under cold environments, extremely long juvenile stages lead to extremely low adult densities, limiting mating opportunities and favouring the evolution of synchronized emergence. Our results indicate that these changes, which were triggered by glacial cooling, could have led to the fixation of periodicity in the non-periodical ancestors.

Extended flowering intervals of bamboos evolved by discrete multiplication

Numerous bamboo species collectively flower and seed at dramatically extended, regular intervals - some as long as 120 years. These collective seed releases, termed 'masts', are thought to be a strategy to overwhelm seed predators or to maximise pollination rates. But why are the intervals so long, and how did they evolve? We propose a simple mathematical model that supports their evolution as a two-step process: First, an initial phase in which a mostly annually flowering population synchronises onto a small multi-year interval. Second, a phase of successive small multiplications of the initial synchronisation interval, resulting in the extraordinary intervals seen today. A prediction of the hypothesis is that mast intervals observed today should factorise into small prime numbers. Using a historical data set of bamboo flowering observations, we find strong evidence in favour of this prediction. Our hypothesis provides the first theoretical explanation for the mechanism underlying this remarkable phenomenon.