Variations and reduction of plastome are associated with the evolution of parasitism in Convolvulaceae.

Parasitic lifestyle can often relax the constraint on the plastome, leading to gene pseudogenization and loss, and resulting in diverse genomic structures and rampant genome degradation. Although several plastomes of parasitic Cuscuta have  been reported, the evolution of parasitism in the family Convolvulaceae which is linked to structural variations and reduction of plastome has not been well investigated. In this study, we assembled and collected 40 plastid genomes belonging to 23 species representing four subgenera of Cuscuta and ten species of autotrophic Convolvulaceae. Our findings revealed nine types of structural variations and six types of inverted repeat (IR) boundary variations in the plastome of Convolvulaceae spp. These structural variations were associated with the shift of parasitic lifestyle, and IR boundary shift, as well as the abundance of long repeats. Overall, the degradation of Cuscuta plastome proceeded gradually, with one clade exhibiting an accelerated degradation rate. We observed five stages of gene loss in Cuscuta, including NAD(P)H complex → PEP complex → Photosynthesis-related → Ribosomal protein subunits → ATP synthase complex. Based on our results, we speculated that the shift of parasitic lifestyle in early divergent time promoted relaxed selection on plastomes, leading to the accumulation of microvariations, which ultimately resulted in the plastome reduction. This study provides new evidence towards a better understanding of plastomic evolution, variation, and reduction in the genus Cuscuta.

Plastid phylogenomic insights into relationships of all flowering plant families.

BACKGROUND: Flowering plants (angiosperms) are dominant components of global terrestrial ecosystems, but phylogenetic relationships at the familial level and above remain only partially resolved, greatly impeding our full understanding of their evolution and early diversification. The plastome, typically mapped as a circular genome, has been the most important molecular data source for plant phylogeny reconstruction for decades. RESULTS: Here, we assembled by far the largest plastid dataset of angiosperms, composed of 80 genes from 4792 plastomes of 4660 species in 2024 genera representing all currently recognized families. Our phylogenetic tree (PPA II) is essentially congruent with those of previous plastid phylogenomic analyses but generally provides greater clade support. In the PPA II tree, 75% of nodes at or above the ordinal level and 78% at or above the familial level were resolved with high bootstrap support (BP ≥ 90). We obtained strong support for many interordinal and interfamilial relationships that were poorly resolved previously within the core eudicots, such as Dilleniales, Saxifragales, and Vitales being resolved as successive sisters to the remaining rosids, and Santalales, Berberidopsidales, and Caryophyllales as successive sisters to the asterids. However, the placement of magnoliids, although resolved as sister to all other Mesangiospermae, is not well supported and disagrees with topologies inferred from nuclear data. Relationships among the five major clades of Mesangiospermae remain intractable despite increased sampling, probably due to an ancient rapid radiation. CONCLUSIONS: We provide the most comprehensive dataset of plastomes to date and a well-resolved phylogenetic tree, which together provide a strong foundation for future evolutionary studies of flowering plants.

Plastid NDH Pseudogenization and Gene Loss in a Recently Derived Lineage from the Largest Hemiparasitic Plant Genus Pedicularis (Orobanchaceae).

The plastid genome (plastome) is highly conserved in both gene order and content and has a lower mutation rate than the nuclear genome. However, the plastome is more variable in heterotrophic plants. To date, most such studies have investigated just a few species or only holoheterotrophic groups, and few have examined plastome evolution in recently derived lineages at an early stage of transition from autotrophy to heterotrophy. In this study, we investigated the evolutionary dynamics of plastomes in the monophyletic and recently derived Pedicularis sect. Cyathophora (Orobanchaceae). We obtained 22 new plastomes, 13 from the six recognized species of section Cyathophora, six from hemiparasitic relatives and three from autotrophic relatives. Comparative analyses of gene content, plastome structure and selection pressure showed dramatic differences among species in section Cyathophora and in Pedicularis as a whole. In comparison with autotrophic relatives and other Pedicularis spp., we found that the inverted repeat (IR) region in section Cyathophora had expansions to the small single-copy region, with a large expansion event and two independent contraction events. Moreover, NA(D)H dehydrogenase, accD and ccsA have lost function multiple times, with the function of accD being replaced by nuclear copies of an accD-like gene in Pedicularis spp. The ccsA and ndhG genes may have evolved under selection in association with IR expansion/contraction events. This study is the first to report high plastome variation in a recently derived lineage of hemiparasitic plants and therefore provides evidence for plastome evolution in the transition from autotrophy to heterotrophy.

Study on the Application of Optical Current Sensor for Lightning Current Measurement of Transmission Line.

Accurate and reliable lightning current data are the basis of lightning protection design. To measure lightning current data at different measurement locations in a transmission system, the limitations of traditional lightning current sensors are analyzed, and optical current sensing technology is adopted, which has the advantages of no magnetic saturation and no bandwidth limitation. Compared with traditional application environments, the sensing technology is used in special environments in transmission systems. This paper analyzes the influence of environmental factors on sensors, and combines the extreme environmental requirements, such as temperature and insulation requirements, to study the sensor. Starting from the sensitivity, the sensing characteristics of the sensor are analyzed. The sensor is designed according to three aspects: sensing material selection, spatial measuring position, and sensing material size optimization, such that it can satisfy the different measurement requirements of towers, overhead ground wires, and transmission lines, respectively. The experiments indicate that the developed sensors can meet the measurement sensitivity requirements of different types of lightning strikes. The experimental results of sensors exhibit a reasonable amplitude measurement accuracy, linearity, and waveform measurement capability. These results provide important theoretical and experimental bases for the application of optical current sensing technology to the measurement of the lightning current of transmission systems.

A Direct Current Measurement Method Based on Terbium Gallium Garnet Crystal and a Double Correlation Detection Algorithm.

When applying an optical current transformer (OCT) to direct current measurement, output signals exhibit a low signal-to-noise ratio and signal-to-noise band overlap. Sinusoidal wave modulation is used to solve this problem. A double correlation detection algorithm is used to extract the direct current (DC) signal, remove white noise and improve the signal-to-noise ratio. Our sensing unit uses a terbium gallium garnet crystal in order to increase the output signal-to-noise ratio and measurement sensitivity. Measurement errors of single correlation and double correlation detection algorithms are compared, and experimental results showed that this measurement method can control measurement error to about 0.3%, thus verifying its feasibility.

Genetic improvement of the nematicidal fungus Lecanicillium attenuatum against Heterodera glycines by expression of the Beauveria bassiana Cdep1 protease gene.

Lecanicillium attenuatum is an important nematophagous fungus with potential as a biopesticide against plant-parasitic nematodes. The Pr1A-like cuticle-degrading protease (Cdep1) gene originating from the entomopathogenic fungus Beauveria bassiana was transformed into the nematophagous fungus L. attenuatum using a polyethylene-glycol mediated protoplast-based transformation system. Protease activity was increased 0.64- to 1.63-fold 2-10d after growth in the transformed L. attenuatum. Inhibition of egg-hatching and J2 motility of soybean cyst nematodes (Heterodera glycines) by cell-free fungal culture filtrates were enhanced by 17-76% 2-14d and 43-152% 1-13d after incubation, respectively.

Pollen size strongly correlates with stigma depth among Pedicularis species.

Darwin proposed that pollen size should be positively correlated with stigma depth rather than style length among species given that pollen tubes first enter the stigma autotrophically, then grow through the style heterotrophically. However, studies often show a positive relationship between pollen size and style length. Five floral traits were observed to be correlated among 42 bumblebee-pollinated Pedicularis species (Orobanchaceae) in which stigmas are distinct from styles. The phylogenetic independent contrast analysis revealed that pollen grain volume was more strongly correlated with stigma depth than with style length, consistent with Darwin's functional hypothesis between pollen size and stigma depth.

Towards a comprehensive phylogeny of the large temperate genus Pedicularis (Orobanchaceae), with an emphasis on species from the Himalaya-Hengduan Mountains.

BACKGROUND: Striking interspecific variations in floral traits of the large temperate genus Pedicularis have given rise to controversies concerning infra-generic classifications. To date, phylogenetic relationships within the genus have not been well resolved. The main goal of this study is to construct a backbone phylogeny of Pedicularis, with extensive sampling of species from the Himalaya-Hengduan Mountains. Phylogenetic analyses included 257 species, representing all 13 informal groups and 104 out of 130 series in the classification system of Tsoong, using sequences of the nuclear ribosomal internal transcribed spacer (nrITS) and three plastid regions (matK, rbcL and trnL-F). Bayesian inference and maximum likelihood methods were applied in separate and combined analyses of these datasets. RESULTS: Thirteen major clades are resolved with strong support, although the backbone of the tree is poorly resolved. There is little consensus between the phylogenetic tree and Tsoong's classification of Pedicularis. Only two of the 13 groups (15.4 %), and 19 of the 56 series (33.9 %) with more than one sampled species were found to be strictly monophyletic. Most opposite-/whorled-leaved species fall into a single clade, i.e. clade 1, while alternate leaves species occur in the remaining 12 clades. Excluding the widespread P. verticillata in clade 1, species from Europe and North America fall into clades 6-8. CONCLUSIONS: Our results suggest that combinations of morphological and geographic characters associated with strongly supported clades are needed to elucidate a comprehensive global phylogeny of Pedicularis. Alternate leaves are inferred to be plesiomorphic in Pedicularis, with multiple transitions to opposite/whorled phyllotaxy. Alternate-leaved species show high diversity in plant habit and floral forms. In the Himalaya-Hengduan Mountains, geographical barriers may have facilitated diversification of species with long corolla tubes, and the reproductive advantages of beakless galeas in opposite-/whorled-leaved species may boost speciation at high altitude.

Distributed parameter model for characterizing magnetic crosstalk in a fiber optic current sensor.

The effects of magnetic crosstalk on a fiber optic current sensor are studied using the distributed parameter model. A new method to enhance the immunity to magnetic crosstalk is proposed. The experimental results show that magnetic crosstalk changes periodically with the azimuth angle and decreases as the distance between the conductors increases. When the sensing coil is placed at the optimal azimuth angle, the ratio error from magnetic crosstalk decreases from -0.32% to -0.02%, demonstrating the effectiveness of the proposed method.

Comparative analyses of mitogenomes in the social bees with insights into evolution of long inverted repeats in the Meliponini.

The insect mitogenome is typically a compact circular molecule with highly conserved gene contents. Nonetheless, mitogenome structural variations have been reported in specific taxa, and gene rearrangements, usually the tRNAs, occur in different lineages. Because synapomorphies of mitogenome organizations can provide information for phylogenetic inferences, comparative analyses of mitogenomes have been given increasing attention. However, most studies use a very few species to represent the whole genus, tribe, family, or even order, overlooking potential variations at lower taxonomic levels, which might lead to some incorrect inferences. To provide new insights into mitogenome organizations and their implications for phylogenetic inference, this study conducted comparative analyses for mitogenomes of three social bee tribes (Meliponini, Bombini, and Apini) based on the phylogenetic framework with denser taxonomic sampling at the species and population levels. Comparative analyses revealed that mitogenomes of Apini and Bombini are the typical type, while those of Meliponini show diverse variations in mitogenome sizes and organizations. Large inverted repeats (IRs) cause significant gene rearrangements of protein coding genes (PCGs) and rRNAs in Indo-Malay/Australian stingless bee species. Molecular evolution analyses showed that the lineage with IRs have lower d N/ d S ratios for PCGs than lineages without IRs, indicating potential effects of IRs on the evolution of mitochondrial genes. The finding of IRs and different patterns of gene rearrangements suggested that Meliponini is a hotspot in mitogenome evolution. Unlike conserved PCGs and rRNAs whose rearrangements were found only in the mentioned lineages within Meliponini, tRNA rearrangements are common across all three tribes of social bees, and are significant even at the species level, indicating that comprehensive sampling is needed to fully understand the patterns of tRNA rearrangements, and their implications for phylogenetic inference.

Mitochondrial genome sequencing and analysis of the invasive Microstegium vimineum: a resource for systematics, invasion history, and management.

Premise of the Research: Plants remain underrepresented among species with sequenced mitochondrial genomes (mitogenomes), due to the difficulty in assembly with short-read technology. Invasive species lag behind crops and other economically important species in this respect, representing a lack of tools for management and land conservation efforts. Methodology: The mitogenome of Microstegium vimineum, one of the most damaging invasive plant species in North America, was sequenced and analyzed using long-read data, providing a resource for biologists and managers. We conducted analyses of genome content, phylogenomic analyses among grasses and relatives based on mitochondrial coding regions, and an analysis of mitochondrial single nucleotide polymorphism in this invasive grass species. Pivotal Results: The assembly is 478,010 bp in length and characterized by two large, inverted repeats, and a large, direct repeat. However, the genome could not be circularized, arguing against a "master circle" structure. Long-read assemblies with data subsets revealed several alternative genomic conformations, predominantly associated with large repeats. Plastid-like sequences comprise 2.4% of the genome, with further evidence of Class I and Class II transposable element-like sequences. Phylogenetic analysis placed M. vimineum with other Microstegium species, excluding M. nudum, but with weak support. Analysis of polymorphic sites across 112 accessions of M. vimineum from the native and invasive ranges revealed a complex invasion history. Conclusions: We present an in-depth analysis of mitogenome structure, content, phylogenetic relationships, and range-wide genomic variation in M. vimineum's invasive US range. The mitogenome of M. vimineum is typical of other andropogonoid grasses, yet mitochondrial sequence variation across the invasive and native ranges is extensive. Our findings suggest multiple introductions to the US over the last century, with subsequent spread, secondary contact, long-distance dispersal, and possibly post-invasion selection on awn phenotypes. Efforts to produce genomic resources for invasive species, including sequenced mitochondrial genomes, will continue to provide tools for their effective management, and to help predict and prevent future invasions.

Comparative analyses of eight complete plastid genomes of two hemiparasitic Cassytha vines in the family Lauraceae.

Cassytha is the sole genus of hemiparasitic vines (ca. 20 spp.) belonging to the Cassytheae tribe of the Lauraceae family. It is extensively distributed in tropical and subtropical regions. In this study, we determined the complete plastid genome sequences of C. filiformis and C. larsenii, which do not possess the typical quadripartite structure. The length of C. filiformis plastomes ranged from 114,215 to 114,618 bp, whereas that of C. larsenii plastomes ranged from 114,900 to 114,988 bp. Comparative genomic analysis revealed 1,013 mutation sites, four large intragenomic deletions, and five highly variable regions in the eight plastome sequences. Phylogenetic analyses based on 61 complete plastomes of Laurales species, 19 ITS sequences, and trnK barcodes from 91 individuals of Cassytha spp. confirmed a non-basal group comprising individuals of C. filiformis, C. larsenii, and C. pubescens in the family Lauraceae and proposed a sister relationship between C. filiformis and C. larsenii. Further morphological comparisons indicated that the presence or absence of hairs on the haustoria and the shape or size of fruits were useful traits for differentiating C. filiformis and C. larsenii.

Fibroblast growth factor 15, induced by elevated bile acids, mediates the improvement of hepatic glucose metabolism after sleeve gastrectomy.

BACKGROUND: Fibroblast growth factor (FGF) 15/19, which is expressed in and secreted from the distal ileum, can regulate hepatic glucose metabolism in an endocrine manner. The levels of both bile acids (BAs) and FGF15/19 are elevated after bariatric surgery. However, it is unclear whether the increase in FGF15/19 is induced by BAs. Moreover, it remains to be understood whether FGF15/19 elevations contribute to improvements in hepatic glucose metabolism after bariatric surgery. AIM: To investigate the mechanism of improvement of hepatic glucose metabolism by elevated BAs after sleeve gastrectomy (SG). METHODS: By calculating and comparing the changes of body weight after SG with SHAM group, we examined the weight-loss effect of SG. The oral glucose tolerance test (OGTT) test and area under the curve of OGTT curves were used to assess the anti-diabetic effects of SG. By detecting the glycogen content, expression and activity of glycogen synthase as well as the glucose-6-phosphatase (G6Pase) and phosphoenolpyruvate carboxykinase (Pepck), we evaluated the hepatic glycogen content and gluconeogenesis activity. We examined the levels of total BA (TBA) together with the farnesoid X receptor (FXR)-agonistic BA subspecies in systemic serum and portal vein at week 12 post-surgery. Then the histological expression of ileal FXR and FGF15 and hepatic FGF receptor 4 (FGFR4) with its corresponding signal pathways involved in glucose metabolism were detected. RESULTS: After surgery, food intake and body weight gain of SG group was decreased compare with the SHAM group. The hepatic glycogen content and glycogen synthase activity was significantly stimulated after SG, while the expression of the key enzyme for hepatic gluconeogenesis: G6Pase and Pepck, were depressed. TBA levels in serum and portal vein were both elevated after SG, the FXR-agonistic BA subspecies: Chenodeoxycholic acid (CDCA), lithocholic acid (LCA) in serum and CDCA, DCA, LCA in portal vein were all higher in SG group than that in SHAM group. Consequently, the ileal expression of FXR and FGF15 were also advanced in SG group. Moreover, the hepatic expression of FGFR4 was stimulated in SG-operated rats. As a result, the activity of its corresponding pathway for glycogen synthesis: FGFR4-Ras-extracellular signal regulated kinase pathway was stimulated, while the corresponding pathway for hepatic gluconeogenesis: FGFR4- cAMP regulatory element-binding protein- peroxisome proliferator-activated receptor γ coactivator-1α pathway was suppressed. CONCLUSION: Elevated BAs after SG induced FGF15 expression in distal ileum by activating their receptor FXR. Furthermore, the promoted FGF15 partly mediated the improving effects on hepatic glucose metabolism of SG.

The complete chloroplast genomes of two Pedicularis species (Orobanchaceae) from Southwest China.

We report the complete chloroplast genome (plastome) sequences of Pedicularis cephalantha (147,087 bp) and P. nigra (145,726 bp), endemic to southwestern China. Both plastomes have typical quadripartite structures with one large-single copy region, one small-single copy region, and two inverted repeat regions. Both plastome sequences contained 37 tRNA genes and eight rRNA genes, but they differed in the numbers of protein-coding genes: P. cephalantha had 76 functional genes and 12 pseudogenes while P. nigra had 74 functional genes and 13 pseudogenes. Phylogenetic analysis shows that P. cephalantha and P. nigra are closely related, then sister to P. oederi in the family Orobanchaceae.

Duodenal-jejunal bypass increases intraduodenal bile acids and upregulates duodenal SIRT1 expression in high-fat diet and streptozotocin-induced diabetic rats.

BACKGROUND: The mechanisms underlying diabetes remission after duodenal-jejunal bypass (DJB) remain elusive. In DJB surgery, the duodenum is excluded. However, the duodenum has emerged as an important regulator of glucose homeostasis, and elevated duodenal SIRT1 leads to improved hepatic insulin sensitivity. After DJB, bile acids (BAs) in the duodenum are not mixed and diluted by the ingested food. And activation of BA receptors promotes SIRT1 expression in many tissues. We hypothesized that BA-mediated upregulation of SIRT1 may contribute to diabetic control after DJB. AIM: To investigate the surgical effects of DJB on duodenal SIRT1 expression and uncover the potential crosslinks between BAs and SIRT1. METHODS: Twenty diabetic rats were randomly allocated to the sham (n = 10) and DJB (n = 10) groups. Body weight, food intake, fasting blood glucose (FBG), serum and intraduodenal total BA (TBA) levels were measured accordingly. Oral glucose tolerance test (OGTT) and intraperitoneal pyruvate tolerance test (ipPTT) were performed to evaluate the effects of surgeries on systemic glucose disposal and hepatic gluconeogenesis. The key genes of BA signaling pathway in the duodenal mucosa, including farnesoid X receptor (FXR), small heterodimer partner (SHP), and Takeda G-protein-coupled receptor 5 (TGR5) were evaluated by real-time quantitative polymerase chain reaction 8 wk postoperatively. The duodenal SIRT1, AMPK, and phosphorylated AMPK (p-AMPK) levels were evaluated by western blotting. Rat small intestine epithelial IEC-6 cells were treated with GW4064 and INT-777 to verify the effects of BAs on SIRT1 expression in enterocytes. RESULTS: The DJB group exhibited body weight and food intake comparable to those of the sham group at all postoperative time points. The FBG level and area under the curve for the OGTT and ipPTT were significantly lower in the DJB group. The DJB group exhibited higher fasting and postprandial serum TBA levels than the sham group at both 2 and 8 wk postoperatively. At 8 wk after surgery, the DJB group showed higher intraluminal TBA concentration, upregulated mRNA expression of FXR and SHP, and elevated protein expression of SIRT1 and p-AMPK in the descending and horizontal segments of the duodenum. Activation of FXR and TGR5 receptors by GW4064 and INT-777 increased the mRNA and protein expression of SIRT1 and promoted the phosphorylation of AMPK in IEC-6 cells. CONCLUSION: DJB elevates intraduodenal BA levels and activates the duodenal BA signaling pathway, which may upregulate duodenal SIRT1 and further contribute to improved glucose homeostasis after DJB.

Increasing Taxa Sampling Provides New Insights on the Phylogenetic Relationship Between Eriobotrya and Rhaphiolepis.

Eriobotrya (Rosaceae) is an economically important genus with around 30 species. It is widely distributed in tropical and warm temperate regions of Asia, with most of its species in China, Myanmar, and Vietnam. However, Eriobotrya is often confused with the smaller genus Rhaphiolepis, and the phylogenetic relationships between the two genera are controversial. Here we present phylogenetic analyses of 38 newly generated Eriobotrya and Rhaphiolepis nrDNA together with 16 sequences of nrDNA and 28 sequences of ITS obtained from GenBank, representing 28 species of Eriobotrya and 12 species of Rhaphiolepis, in order to reconstruct highly supported relationships for the two genera. Contrary to previous research based on limited sampling, our results highlight the monophyly of Eriobotrya as well as Rhaphiolepis. The topology recovered here is consistent with key morphological synapomorphies such as the persistent sepals in Eriobotrya. Our findings show that increased sampling of taxa can provide a more robust phylogeny through reducing phylogenetic error and increasing overall phylogenetic accuracy.

Cryptic Species Diversification of the Pedicularis siphonantha Complex (Orobanchaceae) in the Mountains of Southwest China Since the Pliocene.

Morphological approaches often fail to delimit species in recently derived species complexes. This can be exacerbated in historical collections which may have lost key features in specimen preparation and preservation. Here, we examine the Pedicularis siphonantha complex, endemic to the Mountains of Southwest China. This complex is characterized by its red/purple/pink and long-tubular corolla, and twisted, beaked galea. However, herbarium specimens are often difficult to identify to species. Molecular approaches using nrITS or nuclear ribosomal internal transcribed spacer (nrITS) + plastid DNA (ptDNA) have been successfully used for species identification in Pedicularis. To resolve taxonomic confusion in the Pedicularis siphonantha complex, we reconstructed phylogenies of the complex using nrITS and four plastid DNA loci (matK, rbcL, trnH-psbA, and trnL-F). To recover as much of the phylogenetic history as possible, we sampled individuals at the population level. Topological incongruence between the nrITS and ptDNA datasets was recovered in clades including two widely distributed species, Pedicularis milliana and Pedicularis tenuituba. Based on morphological, geographical, and genetic evidence, we suggest that hybridization/introgression has occurred between P. milliana and Pedicularis sigmoidea/Pedicularis sp. 1 in the Yulong Snow Mountain of Lijiang, northwest Yunnan, and between P. tenuituba and Pedicularis leptosiphon in Ninglang, northwest Yunnan. After removing conflicting DNA regions in Pedicularis dolichosiphon (nrITS) and P. milliana (ptDNA), the concatenated nrITS and ptDNA phylogenies distinguish 11 species in the P. siphonantha complex, including two undescribed species, from the Jiaozi and Yulong Snow Mountains, respectively. Phylogeographical analyses indicate that the P. siponantha complex originated from south of the Hengduan Mountains, expanding north to the Himalayas and the Yunnan-Guizhou Plateau. Moreover, the uplift of the Qinghai-Tibet Plateau and climate oscillations may have driven further diversification in the complex.

Pleistocene origin and colonization history of Lobelia columnaris Hook. f. (Campanulaceae: Lobelioideae) across sky islands of West Central Africa.

We aimed to infer ancestral area and historical colonization of Lobelia columnaris in the sky islands of Bioko and Cameroon through dated phylogeny using chloroplast genomes. Specifically, we aim to answer the following questions: (1) What are the phylogenetic relationships among Bioko Island and Cameroon populations? (2) Are the older populations found in the older sky islands? We assembled novel plastomes from 20 individuals of L. columnaris from 5 mountain systems. The plastome data were explored with phylogenetic analyses using Maximum Likelihood and Bayesian Inference. The populations of L. columnaris have a monophyletic origin, subdivided into three plastomes-geographic clades. The plastid phylogenomic results and age of the sky islands indicate that L. columnaris colonized first along with the Cameroon Volcanic Line's young sky islands of Bioko. The crown group (1.54 Ma) split the population in Bioko and mainland Cameroon. It is possible that Bioko was the ancestral area and likely isolated during cold and dry conditions in forest refugia. Presumably, the colonization history occurred during the middle-late Pleistocene from South Bioko's young sky island to North Bioko and the northern old sky islands in Cameroon. Furthermore, the central depression with lowland forest between North and South Bioko is a current geographic barrier that keeps separating the populations of Bioko from each other. Also, the shallow sea channel keeps isolated the populations of Bioko and the mainland populations. The Pleistocene climatic oscillations led to the divergence of the Cameroon and Bioko populations into three clades. L. columnaris colonized the older sky islands in mainland Cameroon after establishment in Bioko's younger sky islands. Contrary to expectations, the biogeography history was an inverse progression with respect to the age of the Afromontane sky islands.

Characteristics of the complete chloroplast genome sequences of Stylidium debile and Stylidium petiolare (Stylidiaceae).

We report complete chloroplast genome (plastome) sequences of Stylidium debile (150,105 bp) and Stylidium petiolare (150,998 bp). Both plastomes had the typical quadripartite structure, with large single-copy (LSC) and small single-copy (SSC) regions separated by two inverted repeat (IR) regions. Both plastomes have lost the rps19 and ycf15 CDS genes, and had infA-like, rps22-like, and rps7-like pseudogenes. Moreover, IR regions were expanded by having trnH GUG tRNA and the rps22-like pseudogene. Plastome phylogenomic analyses showed that the two Stylidium species formed a monophyletic clade (BS = 100), sister to the Argophyllaceae (BS = 86/83). Sequence differences between the two Stylidium plastomes were 5011 sites, including 2166 variable sites and 2845 indels, with the petA-psbJ spacer the most variable region, followed by the trnK UUU-matK intron and trnG UUG-rps16 spacer.