Podocarpus Species Research Articles

Deep learning approaches to the phylogenetic placement of extinct pollen morphotypes.

The phylogenetic interpretation of pollen morphology is limited by our inability to recognize the evolutionary history embedded in pollen features. Deep learning offers tools for connecting morphology to phylogeny. Using neural networks, we developed an explicitly phylogenetic toolkit for analyzing the overall shape, internal structure, and texture of a pollen grain. Our analysis pipeline determines whether testing specimens are from known species based on uncertainty estimates. Features from specimens with uncertain taxonomy are passed to a multilayer perceptron network trained to transform these features into predicted phylogenetic distances from known taxa. We used these predicted distances to place specimens in a phylogeny using Bayesian inference. We trained and evaluated our models using optical superresolution micrographs of 30 extant Podocarpus species. We then used trained models to place nine fossil Podocarpidites specimens within the phylogeny. In doing so, we demonstrate that the phylogenetic history encoded in pollen morphology can be recognized by neural networks and that deep-learned features can be used in phylogenetic placement. Our approach makes extinction and speciation events that would otherwise be masked by the limited taxonomic resolution of the fossil pollen record visible to palynological analysis.

Detailed Seed Cone Morpho-Anatomy Provides New Insights into Seed Cone Origin and Evolution of Podocarpaceae; Podocarpoid and Dacrydioid Clades.

The study of reproductive morphology and trait evolution provides a vital insight to understand the evolutionary history of plants. The conifer family Podocarpaceae has a remarkable diversity of seed cones, with distinct morphology among the genera and with conifers in general. However, we lack a good understanding of the seed cone morpho-anatomy and trait evolution of Podocarpaceae. We investigated detailed seed cone morpho-anatomy using staining and sectioning techniques to clarify the anatomical, morphological diversity and evolution of functional traits. The presence of a fleshy receptaculum is a characteristic feature of both clades. However, species of Retrophyllum, Afrocarpus and some species of Nageia and Podocarpus form a fleshy sarcotesta-like seed coat, lacking a fleshy receptaculum. The ancestral state reconstructions show a shift between and sometimes within the genus. Although both clades demonstrate fleshiness as an ancestral trait, the shift in fleshy structures provides evidence for complex multiple evolutions of fleshy morphologies. These seed cone traits (e.g., fleshiness and size), along with the broad, flattened and well-adapted (leaf dimorphism) foliage in both clades, are largely congruent with efficient light harvesting and bird dispersal. These traits make these two clades well adapted to their environment, when growing in communities including tall and broad-leaved angiosperms (closed-canopy angiosperm forests), compared to other podocarps, making them more successful in achieving a wider distribution and species richness.

Phytochemical and metabolic profiling of the different Podocarpus species in Egypt: Potential antimicrobial and antiproliferative activities

Podocarpus is the most dominant genus of Podocarpaceae, with higher taxonomical proximity to the Taxaceae, having numerous pharmaceutical applications, however, scarce studies dealing with the physiological and metabolic criteria of Podocarpus in Egypt were reported. Thus, the objective of this work was to assess the physiological and metabolical patterns of the different species of Podocarpus; P. gracilior, P. elongates, P. macrophyllus and P. neriifolius. The highest terpenoids contents were reported in P. neriifolius, followed by P. elongatus, and P. macrophyllus. P. gracilior had the highest antioxidants amount, followed by P. macrophyllus, P. neriifolius and P. elongatus. From the GC/MS metabolic profiling, caryophyllene, β-cadinene, β-cuvebene, vitispirane, β-cadinene and amorphene were the most dominant metabolites in P. gracilior. β-Caryophyllene was the common in P. gracilior, P. elongatus, P. macrophyllus and P. neriifolius with an obvious fluctuation. The plant methanolic extracts have an obvious activity against the multidrug resistant bacteria; E. coli, P. aeruginosa, S. pyogenes and S. aureus, and fungi; A. fumigatus, A. flavus, A. niger and C. albicans in a concentration-dependent manner. The highest Taxol yield was assessed in the extracts of P. elongatus (16.4 μg/gdw), followed by P. macrophyllus, and P. neriifolius. The chemical identity of Taxol derived from P. elongatus was resolved by LC/MS, with molecular mass 854.6 m/z, and similar structural fragmentation pattern of the authentic one. The highest antitumor activity of P. elongatus extracted Taxol was assessed towards HCT-116 (30.2 μg/ml), HepG-2 (53.7 μg/ml) and MCF-7 (71.8 μg/ml). The ITS sequence of P. elongatus “as potent Taxol producer” was deposited on Genbank with accession #ON540734.1, that is the first record of Podocarpus species on Genbank.

Projecting Podocarpaceae response to climate change: we are not out of the woods yet.

Under the changing climate, the persistence of Afrotemperate taxa may be threatened as suitable habitat availability decreases. The unique disjunct ranges of podocarps in southern Africa raise questions about the persistence of these species under climate change. Here, we identified likely environmental drivers of these distributions, characterized the current and future (2070) environmental niches, and projected distributions of four podocarp species in South Africa. Species distribution models were conducted using species locality data for Afrocarpus falcatus, Podocarpus latifolius, Pseudotropheus elongatus and Podocarpus henkelii and both historical climate data (1970-2000) and future climate scenarios (Representative Concentration Pathway [RCP] 4.5 and 8.5, 2061-2080) to estimate the current and future distributions. We also used this opportunity to identify the most important climatic variables that likely govern each species' distribution. Using niche overlap estimates, a similarity test, and indices of niche expansion, stability and unfilling, we explored how niches change under different climate scenarios. The distribution of the study species was governed by the maximum temperature of the warmest month, temperature annual range, mean temperature of the wettest quarter, and precipitation of the wettest, driest and warmest quarters. The current distribution of A. falcatus was predicted to expand to higher elevations under RCP 4.5 and RCP 8.5. Podocarpus henkelii was predicted to lose most of its suitable habitat under RCP 4.5 and expand under RCP 8.5; however, this was the opposite for P. elongatus and P. latifolius. Interestingly, P. elongatus, which had the smallest geographic distribution, showed the most vulnerability to climate change in comparison to the other podocarps. Mapping the distribution of podocarps and understanding the differences in their current and future climate niches provide insight into potential climate drivers of podocarp persistence and the potential for adaptation of these species. Overall, these results suggest that P. elongatus and P. henkelii may expand to novel environmental niches.

A comprehensive review on the medicinal usage of Podocarpus species: Phytochemistry and pharmacology.

Plants of the Podocarpus species belong to the Podocarpaceae family and are largely distributed in the southern hemisphere. Beside the commercially and ecologically valuable, plants of the Podocarpus species are also used in traditional medicines in some countries for treating asthma, fever, venereal diseases, eye diseases, etc. AIM OF THE STUDY: In recent decades, the identities and pharmacological activities of phytochemicals extracted from Podocarpus plants have been widely studied. However, there have been no comprehensive and systematic reviews. This article aims to systematically review the latest research on the putative mechanisms underlying pharmacological actions of phytochemicals from the Podocarpus species, as well as to lay a foundation for promoting the development of plant resources from this genus, further drug research, and product development. A comprehensive search of PubMed, Google Scholar, Web of Science, Elsevier and CNKI databases was conducted using the keywords "Podocarpus", "traditional usage", "phytochemistry", "pharmacology", "nagilactone", etc. Related papers published among July 1964 to February 2023 were collected to summarize the research progress. All plant names were determined through the "The Plant List" (http://www.theplantlist.org/). To date, 262 chemical constituents have been isolated and identified from 26 Podocarpus plants; among these, norditerpene bilactone is the main pharmacologically active component. Norditerpene bilactones are reported to have anti-cancer, anti-inflammatory, antioxidant, antibacterial, anti-tyrosinase, neuroprotective, anti-plasmodial, anti-mutagenic, and anti-atherosclerotic properties as well as other pharmacological activities, which support its traditional uses. Extensive studies on phytochemistry and pharmacology of Podocarpus species lead to discovery of a series of hopeful leading compounds with unique chemical structure, especially the nor- and bis-norditerpenoid dilactones with four isoprene units. These compounds have been proved to possess various pharmacological activities. This review will provide a reference for further research and promote the idea of combining modern research with traditional medicinal applications of Podocarpus plants.

Effects of Acacia melanoxylon, an alien tree species to South Africa, on Afrotemperate forest tree sapling composition

The alien tree Acacia melanoxylon (R.Br.) occurs extensively in the Southern Cape Afrotemperate Forest (South Africa). Concerns exist about its potential negative effects on indigenous tree sapling communities, ultimately with implications for forest composition and structure. We investigated whether Acacia melanoxylon affects Afrotemperate forest tree sapling composition in the Garden Route National Park. Using a paired plot design, we compared sapling species richness, diversity and density underneath 30 overstorey Acacia melanoxylon trees and 30 indigenous counterparts of the species Podocarpus latifolius (Thunb.) R.Br. ex Mirb, Afrocarpus falcatus (Thunb.) C.N.Page, or Olea capensis macrocarpa (C.H.Wright) I.Verd. We recorded 2 503 tree saplings from 27 indigenous species and only three Acacia melanoxylon saplings in the 60 plots. There were no significant differences in the richness, diversity or density of saplings underneath Acacia melanoxylon trees versus their indigenous counterparts. Non-metric multidimensional scaling and cluster analysis accordingly showed only minor differences in sapling species composition and abundance between Acacia melanoxylon and indigenous overstorey trees. We concluded that indigenous tree sapling composition is not significantly altered by the presence of Acacia melanoxylon trees at the densities (< 3 trees ha−1) at which this species commonly occurs in Afrotemperate forest in the Garden Route National Park. However, populations of Acacia melanoxylon in the forest interior act as a source of propagules for invasion in forest margins, riparian areas and neighbouring fynbos shrubland, while at high density the species may alter forest gap-forming dynamics. These invasive attributes need to be considered in the management of the species in the region.

Plastome sequencing of South American Podocarpus species reveals low rearrangement rates despite ancient gondwanan disjunctions.

Historical reconstructions within Podocarpaceae have provided valuable information to disentangle biogeographic scenarios that begun 65 Mya. However, early molecular phylogenies of Podocarpaceae failed to agree on the intergeneric relationships within the family. The aims of this study were to test whether plastome organization is stable within the genus Podocarpus, to estimate the selective regimes affecting plastome protein-coding genes, and to strengthen our understanding of the phylogenetic relationships and biogeographic history. We sequenced the plastomes of four South American species from Patagonia, southern Yungas, and Brazilian subtropical forests. We compared their plastomes to those published from Brazil, Africa, New Zealand, and Southeast Asia, along with representatives from other genera within Podocarpaceae as outgroups. The four newly sequenced plastomes ranged in size between 133,791bp and 133,991bp. Gene content and order among chloroplasts from South American, African and Asian Podocarpus were conserved and different from the plastome of P. totara, from New Zealand. Most genes showed substitution patterns consistent with a conservative selective regime. Phylogenies inferred from either complete sequences or protein coding regions were mostly congruent with previous studies, but showed earlier branching of P. salignus, P. totara and P. sellowii. Highly similar and conserved plastomes of African, South American and Asian species suggest that P. totara plastome should be revised and compared to other species from Oceanic distribution. Furthermore, given such structural conservation, we suggest plastome sequencing is not useful to test whether genomic order can be climatically or geologically structured.

Extraction, characterization of bioactive compounds and biological activities of the leaves of Podocarpus lambertii Klotzch ex Endl

Podocarpus species exhibit anti-inflammatory, antiseptic, astringent activities, and are useful in the treatment of fevers, asthma, coughs, and headaches. This study is the first with the objective of determining the effect of solvent extraction, characterization of bioactive compounds of the essential oil (EO) and plant extracts of Podocarpus lambertii leaves, as well as evaluating the antimicrobial activity by the broth microdilution technique, antioxidant activity by the 2,2-diphenyl-1-picryl hydrazyl (DPPH) method and activity on preformed bacterial biofilms. The yield of the EO was 0.36 %, of the methanolic extracts (ME) 14.9 % and ethanolic extracts (EE) 9.76 %. The analysis of EO (GC-MS) identified 16 compounds: the major components were Manool, 13-epi-, and Rimuene. The phytochemical prospection of the extracts revealed the presence of alkaloids, flavonoids, steroids, and tannins. The extracts showed high antimicrobial activity against Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus, Enterococcus feacalis, Bacillus subtillis, and high antioxidant activity of the ME, with the percentage of DPPH radical sequestration of 84 %. The EO presented low antimicrobial and antioxidant activity. The ME showed high antibiofilm activity of and reduction of the biomass of the biofilm formed most of the bacterial strains tested. The results suggest that the plant extracts of P. lambertii are a promising alternative source of natural bioactive compounds for the control of resistant microorganisms, besides contributing to the knowledge of the species.

Nonstructural carbohydrates predict survival in saplings of temperate trees under carbon stress

Abstract Nonstructural carbohydrates (NSCs) mediate plant survival when the plant's carbon (C) balance is negative, suggesting that NSCs could predict plant survival under C stress. To examine this possibility, we exposed saplings of six temperate tree species to diverse levels of C stress created by the combination of two light conditions (full light availability and deep shade) and two defoliation levels (severe defoliation and nondefoliation). We then measured survival, biomass and total NSCs and soluble sugars (SSs) concentrations in different organs of both dead and live saplings. We estimated mean NSCs and SSs contents and concentrations per sapling and fitted logistic generalized mixed‐effects models to determine if NSCs and SSs predict survival. Using inverse prediction modelling, we also determined whether there is a common NSCs and SSs threshold across species at the time of sapling's death. Defoliation and shade reduced the mean sapling's NSCs and SSs contents, indicating C stress. Mean sapling NSCs and SSs contents and concentrations predicted survival and the robustness of the models improved with the inclusion of species. At death, saplings of the exotic deciduous tree species Acer pseudoplatanus exhibited significantly lower mean NSCs and SSs contents than saplings of the evergreen conifer species Podocarpus nubigenus and lower stem NSCs and SSs concentrations than the broadleaf evergreen species Drimys winteri. The energetic role that NSCs and SSs play in plants under C stress was evidenced by the capacity of these compounds to predict sapling survival under C stress. No common threshold of NSCs and SSs contents or concentrations for sapling survival amongst species was found, indicating that the level of these compounds may not be good proxies for interspecific comparisons of tolerance to C stress. Presumably, there are species‐specific limits for the mobilization and use of NSCs and SSs in metabolism. Our results anticipate that the inclusion of NSCs and SSs in modelling will improve predictions regarding tree responses to ongoing climate change. Nonetheless, a better understanding of the many roles that carbohydrates play in plant survival under C stress is required to scale predictions up to the community level. Read the free Plain Language Summary for this article on the Journal blog.

The effects of heat and drought stress on the ecophysiological responses and growth of Afrocarpus falcatus and Podocarpus henkelii seedlings

Drought and heat are major abiotic stresses that affect recruitment and growth which in turn affects the distribution of species. Plant distribution and forest composition may be determined by species abilities to tolerate and/or avoid drought and heat stress, particularly at the vulnerable seedling stage. Here we investigate the physiological and morphological responses of Afrocarpus falcatus (needle-like leaf) and Podocarpus henkelii (broadleaf) to heat and drought stress. To measure these responses, A. falcatus and P. henkelii seedlings were exposed to heat (ambient, heat wave and heat stress) and drought stress (well-watered and water-stressed) over a 4-week period. Both species showed a significant reduction in maximum quantum yield efficiency of photosystem II (PSII) and chlorophyll content under stressful conditions. Under both stresses P. henkelii was able to maintain minimal fluorescence yield, and maximum activity of PSII. Water use efficiency (WUE) of A. falcatus was significantly reduced under drought stress, while P. henkelii seedlings exposed to drought stress had greater WUE than well-watered seedlings across all heat treatments. Morphologically, leaf senescence and loss were accelerated by the drought and heat treatments in both podocarps. However, the drought and heat treatments did not have a significant effect on biomass allocation pattern, root:shoot ratio and leaf relative water content of A. falcatus and P. henkelii, except for leaf mass fraction in A. falcatus which was significantly reduced by drought and heat stress combined. Overall, the morphological and physiological responses of A. falcatus and P. henkelii to drought and heat stress are indicative of a heat and drought avoidance strategy, allowing both podocarps to persist during heat stress and under limited water availability. This research informs us of the responses of podocarp species to environmental stress, and how this may influence the distribution and potential persistence of these species under current and future environmental conditions.

Potential effect of methanol leaf extracts from three Podocarpus species on experimental cryptosporidiosis.

Cryptosporidiosis causes diarrhea in both immunocompetent and immunocompromised individuals, with acute manifestations occurring particularly in children and the elderly. Up till now, there is no curative therapy for cryptosporidiosis, so discovery of new classes of drugs are of great importance. This study aimed to examine the effect of methanol leaves extracts of the three Podocarpus species; P. macrophyllus (Thunb.), P. gracilior (Pilg.) and P. elongatus (Aiton) L' Hér. ex Pers and their combination on Cryptosporidium parvum (C. parvum) in experimentally infected mice in comparison with the commercially used drug, Nitazoxanide. As well as spectrophotometric estimation of the total phenolic and flavonoid content of these extracts was done. Results revealed that treatment with these three Podocarpus extracts and their combination showed a significant reduction of the number of C. parvum oocyst shed in the stool of infected mice compared to infected control group and Nitazoxanide- infected treated group at P < 0.001. The combination of the three Podocarpus extracts was the most effective treatment showing the lowest number of oocysts shedding in comparison with other used extracts and Nitazoxanide. Histopathological inspection of sections from ilium and colon displayed signs of improvement after treatment with P. macrophyllus and P. gracilior extracts and more remarkable improvement when the three extracts were combined. It was concluded that the three Podocarpus species extracts used in this study had a promising anti-Cryptosporidium activity especially when they were combined.

Bark Anatomy of Podocarpus elongatus (Ait) L.Herit and Screening of Phytochemical Constituents with Antimicrobial Potential

Background: Conifer Podocarpus elongatus belongs to the family Podocarpaceae and some species of Podocarpus are used in traditional medicine. The present study was undertaken to study the anatomical features of the bark of Podocarpus elongatus (Ait) L.Herit. The study was also focused on the antimicrobial activity and phytochemicals present in the bark extract. Methods: The bark was collected from the P. elongatus from Nilgiri Hills of Ooty, Tamil Nadu. The anatomical structures of the bark were elucidated macroscopically and microscopically by using the sectioning techniques. The phytochemical examination was done to confirm the presence of phytochemical components in the methanol extract. The antimicrobial activity was also studied based on the zone of inhibition. Result: The surface of the bark was highly distinguished from other related species, in the pattern of colour, stripes and thickness. Microscopical study envisaged that periderm is characterised by well distinct, continuous structures of the branchy sclereids with thick undulate, continuous segments that have been originated from a deeper cortex. TLS and RLS of the bark view elucidated that the phloem component appeared to be a vertical plane in the fibres. Phloem rays were found as uniseriate with wide sieve cells. Furthermore, antimicrobial activities of the bark exhibited potential effects against examined bacterial and fungal strains.

Stratigraphy and vegetation signals from an upland, landslide-dammed, paleolake during the Last Glacial-Interglacial Transition, Waipaoa Sedimentary System, Hikurangi Margin, eastern North Island, New Zealand

ABSTRACT A recently discovered upland paleolake (Redpath Lake) provides evidence of the expansion of lowland podocarp temperate forest to higher elevations within the tectonically active Waipaoa Sedimentary System (WSS), eastern North Island, New Zealand, during the Last Glacial-Holocene Transition. Interpreted as a localised landslide-dammed lake, lithofacies analyses indicate deposition and preservation in a low energy, sub-aqueous, lacustrine environment. Robust Bayesian-derived age-depth models constrained by key tephra fall beds and independent 14C dating (n = 7) indicate storm-bed frequency of c. 226 yrs on average. The absence of extensive soft-sediment deformation or lake-bed tilting implies that seismic shaking was insignificant during the Lake’s c. 12 ka yr (17.3–5.5 cal ka BP) existence. Pollen spectra extracted from lacustrine deposits include a mix of montane shrubland and lowland podocarp species spanning a well-dated c. 2200-year (c. 16.3–14.1 cal ka BP) period coeval with a phase of significant climate amelioration (late NZCe–5/NZce-4 mild episode), based on biotic proxies during the latter part of the climatically variable Last Glacial-Interglacial Transition (LGIT) (c. 18.2–11.8 cal ka BP). These pollen spectra represent the first New Zealand record of replacement of montane shrublands in terrestrial uplands of the WSS were replaced by lowland podocarp forest.

Diterpenoids Isolated from Podocarpus macrophyllus Inhibited the Inflammatory Mediators in LPS-Induced HT-29 and RAW 264.7 Cells.

Species of Podocarpus are used traditionally in their native areas for the treatment of fevers, asthma, coughs, cholera, chest pain, arthritis, rheumatism, and sexually transmitted diseases. To identify natural products having efficacy against inflammatory bowel disease (IBD), we identified a new, 16-hydroxy-4β-carboxy-O-β-D-glucopyranosyl-19-nor-totarol (4) together with three known diterpenoids from P. macrophyllus. Furthermore, all the extracts, fractions, and isolates 1–4 were investigated for their anti-inflammatory effects by assessing the expression on nitric oxide (NO) production and proinflammatory cytokines in lipopolysaccharide (LPS)-stimulated RAW 264.7 and HT-29 cells. Among them, nagilactone B (2) exhibited a potent anti-inflammatory effect against NO production on RAW 264.7 cells; therefore, nagilactone B was further assessed for anti-inflammatory activity. Western blot analysis revealed that nagilactone B significantly decreased the expression of LPS-stimulated protein, inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, and phosphorylated extracellular regulated kinase (pERK)1/2. In addition, nagilactone B downregulated tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-8 levels in LPS-induced macrophages and colonic epithelial cells. To our best knowledge, this is the first report on the inhibitory effect of nagilactone B (pure state) and rakanmakilactone G against NO production in LPS-stimulated RAW 264.7 cells. Thus, diterpenoids isolated from P. macrophyllus could be employed as potential therapeutic phytochemicals for IBD.

Fossil leaves of Podocarpus subgenus Foliolatus (Podocarpaceae) from the Pliocene of southwestern China and biogeographic history of Podocarpus

Phylogenetic analyses indicate that the genus Podocarpus diverged around the Cretaceous/Paleogene boundary, and two monophyletic subgenera Podocarpus and Foliolatus had differentiated during the Paleogene. Most of described fossil remains were related to the subgenus Podocarpus, but those of the subgenus Foliolatus have not been well documented. Here, we described a new species of Podocarpus, P. yunnanensis sp. nov., and P. cf. forrestii from the lower Pliocene of western Yunnan, China based on a detailed comparisons of gross leaf morphology and cuticular structures between the studied fossils and extant Podocarpus. These two fossil taxa together with P. pliomacrophyllus H. Chen et J.Y. Wu from the same horizon, revealed a thriving of Podocarpus in western Yunnan during the Pliocene. For the subgenus Foliolatus, its early representatives might originate from Australasia and spread northward to northeastern India at least during the late Oligocene. The Neriifolius subclade within the subgenus is much older than the estimate of molecular clock studies, and the Indochinese subclade is probably derived from a rapid diversification driven by the continuous uplift of Hengduan Mountains (HDM) with the accompanying climate fluctuations since the late Miocene. Moreover, the thriving of Podocarpus in the Pliocene of western Yunnan reveals a warm and humid climate during that period. The Pleistocene glaciation and the geographic barriers posted by the HDM might contribute to the modern distribution of Podocarpus in South China and Indochina Peninsula.

Evaluación de parámetros poblacionales y regeneración natural de Podocarpus oleifolius D. Don (Podocarpaceae) en dos relictos boscosos del sur del Ecuador

Populations have structure and dynamics, which are basic features used to understand the ecological processes of species. The native species Podocarpus oleifolius D. Don has ecological and economic importance at a local and national level, therefore, its populations have undergone drastic changes that have generated the formation of small forest relics. Therefore, the present investigation was in charge of studying the spatial distribution, age structure, sex ratio, population density (population parameters) and natural regeneration of Podocarpus oleifolius D. Don in two wooded relics of southern Ecuador, for which 12 plots of 50 m x 50 m were established, six located in the Angashcola communal forest reserve and six in the properties of the Arcoiris Ecological Foundation (San Francisco); in these plots, data were collected on the tree stratum of: DAP, height, sex, crown diameter, phytosanitary status, geographical coordinates; and 60 sub-plots (5 in each plot) of 10 m x 10 m to collect information on natural regeneration. To determine the spatial distribution, the standardized Morisita index (Ip) was used and contrasted with the tool: QGis close neighbor analysis; and to determine the sex ratio, the relationship between males and females was established. The information and results allowed to determine that in the communal forest Angashcola, Amaluza, the population of Podocarpus oleifolius D. Don manifested a pattern of spatial distribution grouped that resulted in a Morisita index of 0.50. The absolute density is 136 ind/ha, where the youngest individuals make up 23.70 % (sapling). 29 female and 12 male individuals were identified in proportion 2.42: 1; three categories of natural regeneration were determined: sapling, low latizal and high latizal; where the sapling category predominates with 91 individuals. The population of Podocarpus oleifolius D. Don manifested a uniform spatial distribution pattern, which resulted in a Morisita index of 1.00 in this site. The absolute density is 22.66 ind/ha, where the youngest individuals and adults represent 28.95 %; the proportion of female and male individuals is 1:1. Three categories of natural regeneration were determined: sapling, low latizal and high latizal; where high latizal predominates with 16 individuals. Therefore, it is essential to continue with related studies in this field of research applied to forest species that play an important ecological role (dominant, key or threatened) within the forest. Keywords: ecology, population parameters, Podocarpus oleifolius, natural regeneration.

Does nitrogen fertilization impact nonstructural carbohydrate storage in evergreen Podocarpus macrophyllus saplings?

Nonstructural carbon (NSC), which represents the relationship between the carbon source and carbon sink, is an important factor that reflects the functions and performance of a tree. However, little is known regarding the time-series responses of NSC storage in evergreen species to different nitrogen (N) fertilization regimes. This study, which was based on a pot experiment, examined the response of the NSC (soluble sugars and starch) storage to different N addition intensities [light N addition (LN): 6.5 g N m−2 a−1; moderate N addition (MN): 13.0 g N m−2 a−1; and heavy N addition (HN): 26.0 g N m−2 a−1)] in saplings of the evergreen species Podocarpus macrophyllus. Our results showed that the net photosynthetic rate (Pn) under MN was significantly higher than that under LN, but was comparable to that under HN. Moreover, saplings subject to MN had a significant higher leaf biomass than that to LN and HN. These results indicated that the C supply via photosynthesis under MN was greater than that under LN and HN. The NSCs reserve under MN was considerable with that under LN, which suggested that saplings in MN group consumed higher and stored lower properties of NSCs than those in LN group. However, saplings under HN stored higher properties of NSCs than those under MN considering that no difference in NSCs pools was found between the two treatments. The leaf N concentrations were found in the increasing sequence of LN < MN < HN, whilst the leaf chlorophyll concentration under HN was obviously lower than that under MN. The growth rate under MN was higher than that under LN and HN. We concluded that the NSCs allocation between consumption and reserve in P. macrophyllus saplings depended on soil N availability, and an excessive N addition to soil favors the storage rather than the consumption of NSCs by plants.

Sex determination in gymnosperms

In gymnosperms dioecy occurs in 64.6%, and sex chromosomes have been identified in 0.6% of the total species. All the Cycadidae, Gnetidae, Ginkgo and some species in Pinidae are dioecious. Heteromorphic sex pairs have been studied in six species where the heteromorphic sex may either be male giving rise to XX/XY system or female resulting in ZZ/WZ system. The chromosome determining the male sex may also be formed by the fusion of two telocentrics resulting in X1X2X1X2/X1X2Y system as in some Podocarpus species. In other cases where chromosomal hetromorphism is undetectable, the molecular markers and functional genomics have been applied to facilitate early sex detection while DNA methylation has also been indicated to be associated with sex determination. The multiple origins of dioecy is evident by its presence in evolutionarily distinct taxa, which provides an opportunity to explore diverse types and their mechanisms of sex determination in this group of plants.

Ups and downs: Genetic differentiation among populations of the Podocarpus (Podocarpaceae) species in Mesoamerica

The biogeographical history of Mesoamerican cloud forests is complex, encompassing a diverse and heterogeneous mixture of species with temperate and tropical origins. The dynamic geological landscape and climate change from the Miocene to the Pleistocene affected the distributions and composition of cloud forests in the region, and contributed to divergence events at different time scales. We assessed genetic variation of 29 populations of P. matudae, and closely related P. guatemalensis and P. oleifolius (Podocarpaceae) by sequencing 255 samples of the psbA-trnH and trnL-F intergenic spacer regions across the species ranges. We conducted phylogenetic, population and spatial genetic analyses as well as divergence time estimation and ecological niche modelling (ENM) to test the generality of demographic and genetic scenarios for cloud forest-adapted species. The results revealed genetic differentiation among species, with some individuals of P. oleifolius and P. guatemalensis placed in the P. matudae group and some P. oleifolius in the P. guatemalensis group. Predictions of ENMs under past climatic conditions and a strong signal of spatial expansion suggest that the highland P. matudae and P. oleifolius populations experienced expansions into lower elevation during the Last Glacial Maximum (LGM). Contrary to predictions by the two precipitation models and elevational ups and downs for cloud forest taxa during the LGM, genetic differentiation and predicted distribution of suitable habitat support the hypotheses that P. matudae and P. oleifolius remained in situ during the LGM primarily within the current fragmented distribution of the cloud forest and spread into the lowlands during the LGM, whereas the distribution of suitable habitat for P. guatemalensis had no major changes upwards from the Last Inter Glacial (LIG) to current conditions.

Recent Taxonomic Notes and New Distribution Localities of Podocarpus Pers. Species in the Philippines

The taxonomy of plants provides a great contribution to understanding diversity and conservation. This study provides additional taxonomic notes on Podocarpus species in the Philippines using newly collected specimens to determine new distribution localities of these species. This study recognises ten species of Podocarpus in the Philippines. Notable results of this study are: (1) the existence of variable leaf forms in P. pilgeri Foxw. correlated to the type of habitat where the species occurs; (2) variable leaf forms and sizes observed in mature and juvenile leaves of all species; (3) support of the sectional arrangement of P. palawanensis de Laub. &amp; Silba; (4) differences between the wild and cultivated representatives of P. costalis C.Presl based on leaf characters; (5) new distributions for P. ramosii R.R.Mill, P. pilgeri, P. costalis, P. neriifolius D.Don, P. rumphii Blume and P. polystachyus R.Br.; (5) no support for the inclusion of P. neglectus Blume and P. hookeri de Laub. as new species found in the Philippines; and (6) comprehensive examination and identification of numerous herbarium specimens and recently collected material.