Tissue Culture via Protocorm-like Bodies in an Orchids Hybrids Paphiopedilum SCBG Huihuang90.

This study successfully established an efficient in vitro propagation system for Paphiopedilum SCBG Huihuang90 via protocorm-like body (PLB) formation from seed-derived calluses, PLB proliferation and differentiation, root induction and greenhouse acclimatization. Furthermore, 1/2 Murashige and Skoog (MS) + 0.025 mg/L 2,4-Dichlorophenoxyacetic acid (2,4-D) was suitable for the proliferation of PLBs, and 1/2MS + 10% coconut water (CW, v/v) + 0.5 g/L activated carbon (AC) was suitable for PLB differentiation. PLBs at different developmental stages required different kinds of sugars. This study provided a reference for research on the propagation techniques of other Paphiopedilum.

Comparative chloroplast genomics of 24 species shed light on the genome evolution and phylogeny of subtribe Coelogyninae (Orchidaceae).

BACKGROUND: The orchids of the subtribe Coelogyninae are among the most morphologically diverse and economically important groups within the subfamily Epidendroideae. Previous molecular studies have revealed that Coelogyninae is an unambiguously monophyletic group. However, intergeneric and infrageneric relationships within Coelogyninae are largely unresolved. There has been long controversy over the classification among the genera within the subtribe. RESULTS: The complete chloroplast (cp.) genomes of 15 species in the subtribe Coelogyninae were newly sequenced and assembled. Together with nine available cp. genomes in GenBank from representative clades of the subtribe, we compared and elucidated the characteristics of 24 Coelogyninae cp. genomes. The results showed that all cp. genomes shared highly conserved structure and contained 135 genes arranged in the same order, including 89 protein-coding genes, 38 tRNAs, and eight rRNAs. Nevertheless, structural variations in relation to particular genes at the IR/SC boundary regions were identified. The diversification pattern of the cp. genomes showed high consistency with the phylogenetic placement of Coelogyninae. The number of different types of SSRs and long repeats exhibited significant differences in the 24 Coelogyninae cp. genomes, wherein mononucleotide repeats (A/T), and palindromic repeats were the most abundant. Four mutation hotspot regions (ycf1a, ndhF-rp132, psaC-ndhE, and rp132-trnL) were determined, which could serve as effective molecular markers. Selection pressure analysis revealed that three genes (ycf1a, rpoC2 and ycf2 genes) might have experienced apparent positive selection during the evolution. Using the alignments of whole cp. genomes and protein-coding sequences, this study presents a well-resolved phylogenetic framework of Coelogyninae. CONCLUSION: The inclusion of 55 plastid genome data from a nearly complete generic-level sampling provide a comprehensive view of the phylogenetic relationships among genera and species in subtribe Coelogyninae and illustrate the diverse genetic variation patterns of plastid genomes in this species-rich plant group. The inferred relationships and informally recognized major clades within the subtribe are presented. The genetic markers identified here will facilitate future studies on the genetics and phylogeny of subtribe Coelogyninae.

Chromosome-level genome assembly and demographic history of Euryodendron excelsum in monotypic genus endemic to China.

Euryodendron excelsum is in a monotypic genus Euryodendron, endemic to China. It has intermediate morphisms in the Pentaphylacaceae or Theaceae families, which make it distinct. Due to anthropogenic disturbance, E. excelsum is currently found in very restricted and fragmented areas with extremely small populations. Although much research and effort has been applied towards its conservation, its long-term survival mechanisms and evolutionary history remain elusive, especially from a genomic aspect. Therefore, using a combination of long/short whole genome sequencing, RNA sequencing reads, and Hi-C data, we assembled and annotated a high-quality genome for E. excelsum. The genome assembly of E. excelsum comprised 1,059,895,887 bp with 99.66% anchored into 23 pseudo-chromosomes and a 99.0% BUSCO completeness. Comparative genomic analysis revealed the expansion of terpenoid and flavonoid secondary metabolite genes, and displayed a tandem and/or proximal duplication framework of these genes. E. excelsum also displayed genes associated with growth, development, and defence adaptation from whole genome duplication. Demographic analysis indicated that its fluctuations in population size and its recent population decline were related to cold climate changes. The E. excelsum genome assembly provides a highly valuable resource for evolutionary and ecological research in the future, aiding its conservation, management, and restoration.

Improved chromosome-level genome assembly of Indian sandalwood (Santalum album).

Santalum album is a well-known aromatic and medicinal plant that is highly valued for the essential oil (EO) extracted from its heartwood. In this study, we present a high-quality chromosome-level genome assembly of S. album after integrating PacBio Sequel, Illumina HiSeq paired-end and high-throughput chromosome conformation capture sequencing technologies. The assembled genome size is 207.39 M with a contig N50 of 7.33 M and scaffold N50 size of 18.31 M. Compared with three previously published sandalwood genomes, the N50 length of the genome assembly was longer. In total, 94.26% of the assembly was assigned to 10 pseudo-chromosomes, and the anchor rate far exceeded that of a recently released value. BUSCO analysis yielded a completeness score of 94.91%. In addition, we predicted 23,283 protein-coding genes, 89.68% of which were functionally annotated. This high-quality genome will provide a foundation for sandalwood functional genomics studies, and also for elucidating the genetic basis of EO biosynthesis in S. album.

Identification of HpMYB1 inducing anthocyanin accumulation in Hippeastrum Hybridum tepals by RNA-seq.

BACKGROUND: Cultivated Hippeastrum × hybridum is a popular ornamental plant with large and colorful flowers, long flowering duration, and high commercial value. As its main ornamental feature, its flower color is related to the anthocyanin content in the tepals. However, the molecular regulatory mechanisms of anthocyanin biosynthesis in H. × hybridum have not yet been elucidated. RESULTS: In the present study, 12 cDNA libraries of four stages of H.× hybridum 'Royal Velvet' tepal development were used for RNA-seq, obtaining 79.83 gigabases (GB) of clean data. The data were assembled into 148,453 unigenes, and 11,262 differentially expressed genes were identified. Forty key enzymes participating in anthocyanin biosynthesis were investigated, and the results showed that most of the anthocyanin structural genes were expressed at low levels in S1 and were markedly upregulated in S2 and S3. The expression profiles of 12 selected genes were verified by qRT-PCR. Furthermore, the R2R3-MYB transcription factor (TF), HpMYB1, involved in the regulation of anthocyanin biosynthesis was identified by sequence, expression pattern, and subcellular localization analyses. Its overexpression in tobacco significantly increased the anthocyanin levels in various tissues and activated anthocyanin-related genes. CONCLUSIONS: Using RNA-seq technology, we successfully identified a potential R2R3-MYB gene, HpMYB1, that regulates anthocyanin biosynthesis in H.× hybridum 'Royal Velvet'. Our findings provide basic transcript information and valuable transcriptome data for further identification of key genes involved in anthocyanin biosynthesis and can be applied in the artificial breeding of new H. × hybridum cultivars with enhanced ornamental value.

Gibberellic Acid Inhibits Dendrobium nobile-Piriformospora Symbiosis by Regulating the Expression of Cell Wall Metabolism Genes.

Orchid seeds lack endosperms and depend on mycorrhizal fungi for germination and nutrition acquisition under natural conditions. Piriformospora indica is a mycorrhizal fungus that promotes seed germination and seedling development in epiphytic orchids, such as Dendrobium nobile. To understand the impact of P. indica on D. nobile seed germination, we examined endogenous hormone levels by using liquid chromatography-mass spectrometry. We performed transcriptomic analysis of D. nobile protocorm at two developmental stages under asymbiotic germination (AG) and symbiotic germination (SG) conditions. The result showed that the level of endogenous IAA in the SG protocorm treatments was significantly higher than that in the AG protocorm treatments. Meanwhile, GA3 was only detected in the SG protocorm stages. IAA and GA synthesis and signaling genes were upregulated in the SG protocorm stages. Exogenous GA3 application inhibited fungal colonization inside the protocorm, and a GA biosynthesis inhibitor (PAC) promoted fungal colonization. Furthermore, we found that PAC prevented fungal hyphae collapse and degeneration in the protocorm, and differentially expressed genes related to cell wall metabolism were identified between the SG and AG protocorm stages. Exogenous GA3 upregulated SRC2 and LRX4 expression, leading to decreased fungal colonization. Meanwhile, GA inhibitors upregulated EXP6, EXB16, and EXP10-2 expression, leading to increased fungal colonization. Our findings suggest that GA regulates the expression of cell wall metabolism genes in D. nobile, thereby inhibiting the establishment of mycorrhizal symbiosis.

An Activated Structure Transformable Ratiometric Photoacoustic Nanoprobe for Real-Time Dynamic Monitoring of H2S In Vivo.

H2S has emerged as a promising biomarker for many diseases such as colon cancer and metformin-induced hepatotoxicity. Real-time monitoring of H2S levels in vivo is significant for early accurate diagnosis of these diseases. Herein, a new accurate and reliable nanoprobe (Au NRs@Ag) was designed for real-time dynamic ratiometric photoacoustic (PA) imaging of H2S in vivo based on the endogenous H2S-triggered local surface plasmon resonance (LSPR) red-shift. The Au NRs@Ag nanoprobe can be readily converted into Au NRs@Ag2S via the endogenous H2S-activated in situ sulfurative reaction, subsequently leading to a significant red-shift of the LSPR wavelength from 808 to 980 nm and enabling accurate ratiometric PA (PA980/PA808) imaging of H2S. Moreover, dynamic ratiometric PA imaging of metformin-induced hepatotoxicity was also successfully achieved by the designed PA imaging strategy. These findings provide the possibility of designing a new ratiometric PA imaging strategy for dynamic in situ monitoring of H2S-related diseases.

Correction: Hybrid lanthanide nanoparticles as a new class of binary contrast agents for in vivo T1/T2 dual-weighted MRI and synergistic tumor diagnosis.

Correction for 'Hybrid lanthanide nanoparticles as a new class of binary contrast agents for in vivo T1/T2 dual-weighted MRI and synergistic tumor diagnosis' by Zhigao Yi et al., J. Mater. Chem. B, 2016, 4, 2715-2722, https://doi.org/10.1039/C5TB02375K.

The Complete Chloroplast Genomes of Blepharoglossum elegans and B. grossum and Comparative Analysis with Related Species (Orchidaceae, Malaxideae).

Blepharoglossum is a rare orchid genus of the Malaxidinae primarily distributed in tropical Pacific islands, with several species occurring in the Taiwan and Hainan Islands of China. Currently, the monophyletic status of Blepharoglossum has been challenged, and the phylogenetic relationships among its allied groups have remained unresolved with traditional DNA markers. In this study, we initially sequenced and annotated the chloroplast (cp) genomes of two Blepharoglossum species, Blepharoglossum elegans (Lindl.) L. Li and Blepharoglossum grossum (Rchb.f.) L. Li. These cp genomes of Blepharoglossum share the typical quadripartite and circular structure. Each of the genomes encodes a total of 133 functional genes, including 87 protein-coding genes (CDS), 38 tRNA genes and 8 rRNA genes. By comparing the sequence differences between these two cp genomes, it was found that they are relatively conserved in terms of overall gene content and gene arrangement. However, a total of 684 SNPs and 2664 indels were still identified, with ycf1, clpP, and trnK-UUU protein-coding genes having the highest number of SNPs and indels. In further comparative analyses among the six cp genomes in Malaxidinae, significant sequence divergences were identified in the intergenic regions, namely rps16-trnQ-UUG, trnS-GCU-trnG-GCC, rpoB-trnC-GCA, trnE-UUC-trnT-GGU, trnF-GAA-trnV-UAC, atpB-rbcL, petA-psbJ, psbE-petL, psbB-psbT, trnN-GUU-rpl32, trnV-GAC-rps7, and rps7-trnL-CAA, and five coding regions, including matK, and rpoC2, ycf1, and two ycf2 genes. Phylogenetic analysis indicated that Blepharoglossum and Oberonia form a highly supported sister group relationship. Our results are consistent with previous studies and present increased resolution among major clades.

Comparative analyses and phylogenetic relationships of thirteen Pholidota species (Orchidaceae) inferred from complete chloroplast genomes.

BACKGROUND: The orchid genus Pholidota Lindl. ex Hook. is economically important as some species has long been used in traditional medicine. However, the systematic status of the genus and intergeneric relationships inferred from previous molecular studies are unclear due to insufficient sampling and lack of informative sites. So far, only limited genomic information has been available. The taxonomy of Pholidota remains unresolved and somewhat controversial. In this study, the complete chloroplast (cp.) genomes of thirteen Pholidota species were sequenced and analyzed to gain insight into the phylogeny of Pholidota and mutation patterns in their cp. genomes. RESULTS: All examined thirteen Pholidota cp. genomes exhibited typical quadripartite circular structures, with the size ranging from 158,786 to 159,781 bp. The annotation contained a total of 135 genes in each cp. genome, i.e., 89 protein-coding genes, 38 tRNA genes, and eight rRNA genes. The codon usage analysis indicated the preference of A/U-ending codons. Repeat sequence analysis identified 444 tandem repeats, 322 palindromic repeats and 189 dispersed repeats. A total of 525 SSRs, 13,834 SNPs and 8,630 InDels were detected. Six mutational hotspots were identified as potential molecular markers. These molecular markers and highly variable regions are expected to facilitate future genetic and genomic studies. Our phylogenetic analyses confirmed the polyphyletic status of the genus Pholidota, with species grouped into four main clades: Pholidota s.s. was resolved as the sister to a clade containing species of Coelogyne; the other two clades clustered together with species of Bulleyia and Panisea, respectively; species P. ventricosa was placed at the basal position, deviated from all other species. CONCLUSION: This is the first study to comprehensively examine the genetic variations and systematically analyze the phylogeny and evolution of Pholidota based on plastid genomic data. These findings contribute to a better understanding of plastid genome evolution of Pholidota and provide new insights into the phylogeny of Pholidota and its closely related genera within the subtribe Coelogyninae. Our research has laid the foundation for future studies on the evolutionary mechanisms and classification of this economically and medicinally important genus.

NIR-II Light-Activated Gold Nanorods for Synergistic Thermodynamic and Photothermal Therapy of Tumor.

There are tricky challenges in tumor therapy due to the hypoxic tumor microenvironment, inevitably inhibiting the treatment efficacy of the traditional photodynamic therapy (PDT), radiation therapy (RT), and sonodynamic therapy (SDT). Herein, to overcome tumor hypoxia limitation, we constructed a near-infrared II (NIR-II) light-triggered thermodynamic therapy (TDT) nanoplatform of Au@mSiO2-AIPH@PCM/PEG (ASAPP) by integrating the Au nanorods (Au NRs) and thermally activated alkyl free radical-releasing molecules (AIPH). Au NRs@mSiO2 was used as a photothermally responsive material and AIPH carrier, and the hot-melt phase-change material (PCM) was used as a capping agent to prevent leakage of AIPH during blood circulation. Upon NIR-II light irradiation, heat-triggered free radical release from AIPH was successfully achieved for killing cancer cells in vitro and in vivo without oxygen dependence, leading to synergistically enhanced antitumor therapy.

Transcriptomic analysis reveals biosynthesis genes and transcription factors related to leaf anthocyanin biosynthesis in Aglaonema commutatum.

BACKGROUND: Aglaonema commutatum 'Red Valentine', as a foliage ornamental plant, is widely used for interior and exterior decoration because of its easy cultivation and management. However, reduced proportion of red foliage during large-scale production of A. commutatum seedlings is a frequent occurrence, which has considerable implications on the plant's ornamental and market value. However, the molecular mechanisms underlying this phenomenon remain unclear. RESULTS: To explore the molecular basis of the variation in leaf color of A. commutatum Red Valentine, we performed transcriptome sequencing with the Illumina platform using two different varieties of A. commutatum, namely Red Valentine and a green mutant, at three different stages of leaf development. We annotated 63,621 unigenes and 14,186 differentially expressed genes by pairwise comparison. Furthermore, we identified 26 anthocyanin biosynthesis structural genes. The transcript per million (TPM) values were significantly higher for Red Valentine than for the green mutant in all three developmental stages, consistent with the high anthocyanin content of Red Valentine leaves. We detected positive transcription factors that may be involved in the regulation of anthocyanin biosynthesis using BLAST and through correlation analysis. Downregulation of these transcription factors may downregulate the expression of anthocyanin genes. We obtained full-length cDNA of the anthocyanin biosynthesis and regulatory genes and constructed phylogenetic trees to ensure accuracy of the analysis. CONCLUSIONS: Our study provides insights into the molecular mechanisms underlying leaf variation in A. commutatum Red Valentine and may be used to facilitate the breeding of ornamental cultivars with high anthocyanin levels.

NIR-II Responsive Upconversion Nanoprobe with Simultaneously Enhanced Single-Band Red Luminescence and Phase/Size Control for Bioimaging and Photodynamic Therapy.

Lanthanide based upconversion (UC) nanoprobes have emerged as promising agents for biological applications. Extending the excitation light to the second near-infrared (NIR-II), instead of the traditional 980/808 nm light, and realizing NIR-II responsive single-band red UC emission is highly demanded for bioimaging application, which has not yet been explored. Here, a new type of NIR-II (1532 nm) light responsive UC nanoparticles (UCNPs) with enhanced single-band red UC emission and controllable phase and size is designed by introducing Er3+ as sensitizer and utilizing Mn2+ as energy manipulator. Through tuning the content of Mn2+ in NaLnF4 :Er/Mn, the crystal phase, size, and emitting color are readily controlled, and the red-to-green (R/G) ratio is significantly increased from ≈20 to ≈300, leading to NIR-II responsive single band red emission via efficient energy transfer between Er3+ and Mn2+ . In addition, the single band red emitting intensity can be further improved by coating shell to avoid the surface quenching effect. More importantly, NIR-II light activated red UC bioimaging and photodynamic therapy through loading photosensitizer of zinc phthalocyanine are successfully achieved for the first time. These findings provide a new strategy of designing NIR-II light responsive single-band red emissive UCNPs for biomedical applications.

Shoot organogenesis and somatic embryogenesis from leaf and petiole explants of endangered Euryodendron excelsum.

Euryodendron excelsum H.T. Chang is a rare and endangered woody plant endemic to China. It is very important to conserve and propagate this species from extinction. In this study, leaves and petioles from the axillary shoots in vitro were used as explants to culture on the different plant growth regulator (PGR) woody plant medium (WPM) and establish an efficient shoot proliferation and plant regeneration system. WPM supplemented with 1.0 mg/L 2,4-D induced callus dedifferentiated into buds and somatic embryos on various media,including PGR-free WPM. However, only adventitious shoots formed on WPM with 1.0 mg/L of cytokinins such as 6-benzyladenine (BA), kinetin (KIN) or thidiazuron (TDZ). When another cytokinin, zeatin, was used, somatic embryos were induced directly from From cut surface of these explants. Adventitious roots could be induced from both explants on WPM with 1.0 mg/L α-naphthaleneacetic acid (NAA). Somatic embryos cultured in PGR-free WPM or WPM with 0.2 mg/L NAA developed roots. Plantlets derived from somatic embryos were transferred to a peat: sand (1:1, v/v) substrate, and showed survival rates of 64.3% at 30 days and 54.6% at 90 days. Callus clumps with adventitious shoot buds that were transferred to WPM containing 1.0 mg/L BA and 0.2 mg/L NAA generated a mean 3.3 multiple shoots. Callus-derived shoots regenerated and rooted successfully (100%) on agar-free vermiculite-based WPM with 0.5 µM NAA after 30 d. Plantlets transplanted to peat soil: vermiculite (1:1, v/v) displayed the highest survival (96.7%) after three months.

The complete chloroplast genome of Stichorkis gibbosa (Orchidaceae: Malaxideae).

Stichorkis gibbosa is a rare orchid species of the tribe Malaxideae mainly distributed in tropical Asia. This is the only species of the genus Stichorkis Thouars which has been reported to occur in China. Despite the importance of this genus, previous molecular studies based on few markers have resulted in limited phylogenetic resolution. With the decline of habitats, the wild population of S. gibbosa has decreased in recent years. In this study, we first reported the complete chloroplast (cp) genome of S. gibbosa. The entire cp genome was determined to be 158,056 bp in length with overall GC content of 36.9%, containing a pair of inverted repeat regions (IRs) of 27,006 bp, separated by a large single-copy (LSC, 86,280 bp) and a small single-copy (SSC, 17,764 bp). A total of 133 unique genes were annotated, including 87 protein-coding genes, 38 tRNA genes, and eight rRNA genes. The phylogenetic tree indicated that S. gibbosa was a sister group of the genus Oberonia and the epiphytic Liparis alliance with strong support.

Recyclable Endogenous H2 S Activation of Self-Assembled Nanoprobe with Controllable Biodegradation for Synergistically Enhanced Colon Cancer-Specific Therapy.

Excessive production of hydrogen sulfide (H2 S) plays a crucial role in the progress of colon cancer. Construction of tumor-specific H2 S-activated smart nanoplatform with controllable biodegradation is of great significance for precise and sustainable treatment of colon cancer. Herein, an endogenous H2 S triggered Co-doped polyoxometalate (POM-Co) cluster with self-adjustable size, controlled biodegradation, and sustainable cyclic depletion of H2 S/glutathione (GSH) is designed for synergistic enhanced tumor-specific photothermal and chemodynamic therapy. The designed POM-Co nanocluster holds H2 S responsive "turn-on" photothermal property in colon cancer via self-assembling to form large-sized POM-CoS, enhancing the accumulation at tumor sites. Furthermore, the formed POM-CoS can gradually biodegrade, resulting in release of Co2+ and Mo6+ for Co(II)-catalyzed •OH production and Russell mechanism-enabled 1 O2 generation with GSH consumption, respectively. More importantly, the degraded POM-CoS is reactivated by endogenous H2 S for recyclable and sustainable consumption of H2 S and GSH, resulting in tumor-specific photothermal/chemodynamic continuous therapy. Therefore, this study provides an opportunity of designing tumor microenvironment-driven nanoprobes with controllable biodegradation for precise and sustainable anti-tumor therapy.

AcMYB1 Interacts With AcbHLH1 to Regulate Anthocyanin Biosynthesis in Aglaonema commutatum.

Aglaonema commutatum is one of the most popular foliage plants with abundant leaf phenotypes; therefore, anthocyanin coloration is a vital economic trait in A. commutatum. However, the molecular mechanisms underlying anthocyanin biosynthesis and its regulation remain unclear. In this study, AcMYB1 and AcbHLH1, transcription factor genes related to an R2R3-myeloblast (MYB) and a basic helix-loop-helix (bHLH), respectively, were isolated from A. commutatum "Red Valentine" and functionally characterized. AcMYB1 and AcbHLH1 were found to interact by Y2H and BiFC assay. AcMYB1 was grouped into the AN2 subgroup and shared high homology with the known regulators of anthocyanin biosynthesis. Gene expression analysis showed that both AcMYB1 and AcbHLH1 have similar expression patterns to anthocyanin structural genes and correlate with anthocyanin distribution in different tissues of A. commutatum. Light strongly promoted anthocyanin accumulation by upregulating the expression of anthocyanin-related genes in A. commutatum leaves. Ectopic expression of AcMYB1 in tobacco remarkably increased anthocyanin accumulation in both vegetative and reproductive tissues at various developmental stages. These results provide insights into the regulation of anthocyanin biosynthesis in A. commutatum and are useful for breeding new A. commutatum cultivars with enhanced ornamental value.

Exogenous GA3 promotes flowering in Paphiopedilum callosum (Orchidaceae) through bolting and lateral flower development regulation.

Paphiopedilum orchids have a high ornamental value, and their flower abundance and timing are both key horticultural traits regulated by phytohormones. All one-flowered Paphiopedilum have additional lateral buds in the apical bract that fail to develop. In this study, an exogenous gibberellin (GA3) application promoted flowering of Pathiopedilum callosum by inducing its early bolting instead of the floral transition of dominant flowers. Applying GA3 effectively promoted lateral flower differentiation, resulting in a two-flowered inflorescence. GA-promoted lateral flower formation involved GA interacting with indole-3-acetic acid (IAA) and cytokinins (CTKs), given the decreased CTK content and downregulated expression of CTK synthesis genes, the increased IAA content and downregulated expression of IAA degradation, and the upregulated expression of transport genes. Further, GA acted via PcDELLA, PcTCP15, and PcXTH9 expressed in stage 5 to promote bolting, and via expression of PcAP3, PcPI, and PcSEP to promote flowering. This study provides insight into mechanisms regulating flower development of P. callosum.

Comparative Chloroplast Genomics and Phylogenetic Analysis of Thuniopsis and Closely Related Genera within Coelogyninae (Orchidaceae).

The genus Thuniopsis was recently proposed for a rare orchid species T. cleistogama formerly classified in the genus Thunia. The relationships between Thuniopsis and its related genera have not yet been conclusively resolved. Recognition of the genus provides a new perspective to illustrate the morphological diversity and plastome evolution within Coelogyninae. In this study, we sequenced and assembled complete chloroplast (cp) genomes for three accessions of Thuniopsis cleistogama and two accessions of Thunia alba. A total of 135 genes were annotated for each cp genome, including 89 protein-coding genes, 38 tRNA genes, and eight rRNA genes. The ENC-plot and neutrality plot analyses revealed that natural selection dominated over mutation pressure in their evolutionary process. Specially, we found that selection played a vital role in shaping the codon usage in Thunia alba cp genome. General characteristics of the cp genomes were further analyzed and compared with those published plastomes of four other related species. Despite the conserved organization and structure, the whole individual cp genome size ranged from 158,394 bp to 159,950 bp. In all the examined plastomes, sequences in the inverted repeat (IR) regions were more conserved than those in the small single copy (SSC) and large single copy (LSC) regions. However, close examination identified contraction and expansion of the IR/SSC boundary regions, which might be the main reason for the cp genome size variation. Our comparative analysis of the cp genomes revealed that single nucleotide polymorphisms (SNPs) and insertions/deletions (InDels) provided valuable information for identifying genetic variations within and among genera. Furthermore, sequence variations in the protein-coding regions were more conserved than those in the non-coding regions. We selected eight divergence hotspots with nucleotide sequence diversities (Pi values) higher than 0.08. Most of these polymorphisms were located in the intergenic regions. Phylogenomic analyses recovered largely congruent relationships among major clades and strongly supported the monophyly of Thuniopsis. The results obtained in this study can improve our understanding of the classification of this enigmatic genus. The chloroplast genomic data presented here provide valuable insights into the phylogeny and evolutionary patterns of the Coelogyninae as well as the orchids as a whole.

Intelligent Nanotransducer for Deep-Tumor Hypoxia Modulation and Enhanced Dual-Photosensitizer Photodynamic Therapy.

Upconversion nanoparticles (UCNPs) emerged as promising near-infrared (NIR) light-triggered nanotransducers for photodynamic therapy (PDT). However, the traditionally used 980 nm excitation source could cause an overheating effect on biological tissues, and the single photosensitizer (PS) loading could not efficiently utilize multiradiation UC luminescence, resulting in a limited efficiency of PDT in tumor tissues with hypoxia characteristics. Herein, 808 nm light-responsive Nd-sensitized UCNPs@mSiO2@MnO2 core-shell NPs were designed as light nanotransducers with efficient UC emission at 550 and 650 nm for PDT and downshifting luminescence at 1525 nm for second NIR (NIR-II) imaging. UC emission was fully utilized by loading dual PSs, rose bengal (RB), and zinc phthalocyanine (ZnPc), thus significantly improving the reactive oxide species (ROS) generation efficiency. Moreover, a manganese dioxide (MnO2) shell with ultrasensitive biodegradability in an acidic tumor microenvironment (TME) can generate an amount of oxygen molecules, alleviating the symptoms of hypoxia and then improving the efficacy of PDT. Meanwhile, the biodegraded Mn2+ ions can further strengthen T1-weighted magnetic resonance imaging (MRI). This work presented a new multifunctional theranostic agent for combining NIR-II/MRI imaging and 808 nm light-triggered PDT to combat the limitations of cancer therapy.