Identification and Expression Analysis of Putative Sugar Transporter Gene Family during Bulb Formation in Lilies.

Sugar transporters play important roles in plant growth and development, flowering and fruiting, as well as responses to adverse abiotic and biotic environmental conditions. Lilies (Lilium spp.) are some of the most representative ornamental bulbous flowers. Sugar metabolism is critical for bulb formation in lilies; therefore, clarifying the amount and expression pattern of sugar transporters is essential for further analyzing their roles in bulb formation. In this study, based on the transcriptome data of the Lilium Oriental hybrid 'Sorbonne' and Lilium × formolongi, a total of 69 and 41 sugar transporters were identified in 'Sorbonne' and Lilium × formolongi, respectively, by performing bioinformatics analysis. Through phylogenetic analysis, monosaccharide transporters (MSTs) can be divided into seven subfamilies, sucrose transporters (SUTs) can be divided into three subgroups, and sugars will eventually be exported transporters (SWEETs) can be divided into four clades. According to an analysis of conserved motifs, 20, 14, and 12 conserved motifs were predicted in MSTs, SUTs, and SWEETs, respectively. A conserved domain analysis showed that MSTs and SUTs contained a single domain, whereas most of the SWEETs harbored two MtN3/saliva domains, also known as a PQ-loop repeat. The LohINT1, which was predicted to have a smaller number of transmembrane structural domains, was cloned and analyzed for subcellular localization. It was found that the LohINT1 protein is mainly localized in the cell membrane. In addition, the expression analysis indicated that 22 LohMSTs, 1 LohSUTs, and 5 LohSWEETs were upregulated in 'Sorbonne' 1 day after scale detachment treatment, suggesting that they may regulate the initiation of the bulblet. A total of 10 LflMSTs, 1 LflSUTs, and 6 LflSWEETs were upregulated 4~6 months after sowing, which corresponds to the juvenile-to-adult transition phase of Lilium × formolongi, suggesting that they may also play a role in the accompanying bulb swelling process. Combined with quantitative real-time PCR (qRT-PCR) analysis, LohSTP8 and LohSTP12 were significantly overexpressed during the extremely early stage of bulblet initiation, and LflERD6.3 was significantly overexpressed during the growth of the underground bulblet, suggesting that they may be key sugar transporters in the formation of lily bulbs, which needs further functional verification.

Full-length transcriptome analysis revealed that 2,4-dichlorophenoxyacetic acid promoted in vitro bulblet initiation in lily by affecting carbohydrate metabolism and auxin signaling.

Bulblet initiation, including adventitious bud initiation and bulblet formation, is a crucial process for lily and other bulbous flowers that are commercially propagated by vegetative means. Here, by a hybrid strategy combining Pacific Biosciences (PacBio) full-length sequencing and Illumina RNA sequencing (RNA-seq), high-quality transcripts of L. brownii (Lb) and its variety, L. brownii var. giganteum (Lbg), during in vitro bulblet initiation were obtained. A total of 53,576 and 65,050 high-quality non-redundant full-length transcripts of Lbg and Lb were generated, respectively. Morphological observation showed that Lbg possessed a stronger capacity to generate bulblets in vitro than Lb, and 1 mg L-1 2,4-dichlorophenoxyacetic acid (2,4-D) significantly increased bulblet regeneration rate in two lilies. Screening of differentially expressed transcripts (DETs) between different stages and Mfuzz analysis showed 0 DAT to 1 DAT was the crucial stage with the most complex transcriptional change, with carbohydrate metabolism pathway was significantly enriched. In addition, 6,218 and 8,965 DETs were screened between the 2,4-D-treated group and the control group in Lbg and Lb, respectively. 2,4-D application had evident effects on the expression of genes involved in auxin signaling pathway, such as TIRs, ARFs, Aux/IAAs, GH3s and SAURs. Then, we compared the expression profiles of crucial genes of carbohydrate metabolism between different stages and different treatments. SUSs, SUTs, TPSs, AGPLs, GBSSs and SSs showed significant responses during bulblet initiation. The expression of CWINs, SUTs and SWEETs were significantly upregulated by 2,4-D in two lilies. In addition, 2,4-D increased the expression of starch degradation genes (AMYs and BAMs) and inhibited starch synthesis genes (AGPLs, GBSSs and SSs). SBEs were significantly upregulated in Lbg but not in Lb. Significant co-expression was showed between genes involved in carbohydrate metabolism and auxin signaling, together with transcription factors such as bHLHs, MYBs, ERFs and C3Hs. This study indicates the coordinate regulation of bulblet initiation by carbohydrate metabolism and auxin signaling, serving as a basis for further studies on the molecular mechanism of bulblet initiation in lily and other bulbous flowers.

Identifying, Resolving, and Quantifying Anisotropy in ReS2 Nanomechanical Resonators.

As an emerging two-dimensional semiconductor, rhenium disulfide (ReS2 ) is renowned for its strong in-plane anisotropy in electrical, optical, and thermal properties. In contrast to the electrical, optical, optoelectrical, and thermal anisotropies that are extensively studied in ReS2 , experimental characterization of mechanical properties has largely remained elusive. Here, it is demonstrated that the dynamic response in ReS2 nanomechanical resonators can be leveraged to unambiguously resolve such disputes. Using anisotropic modal analysis, the parameter space for ReS2 resonators in which mechanical anisotropy is best manifested in resonant responses is determined. By measuring their dynamic response in both spectral and spatial domains using resonant nanomechanical spectromicroscopy, it is clearly shown that ReS2 crystal is mechanically anisotropic. Through fitting numerical models to experimental results, it is quantitatively determined that the in-plane Young's moduli are 127 and 201 GPa along the two orthogonal mechanical axes. In combination with polarized reflectance measurements, it is shown that the mechanical soft axis aligns with the Re-Re chain in the ReS2 crystal. These results demonstrate that dynamic responses in nanomechanical devices can offer important insights into intrinsic properties in 2D crystals and provide design guidelines for future nanodevices with anisotropic resonant responses.

ATM-mediated double-strand break repair is required for meiotic genome stability at high temperature.

In eukaryotes, meiotic recombination maintains genome stability and creates genetic diversity. The conserved Ataxia-Telangiectasia Mutated (ATM) kinase regulates multiple processes in meiotic homologous recombination, including DNA double-strand break (DSB) formation and repair, synaptonemal complex organization, and crossover formation and distribution. However, its function in plant meiotic recombination under stressful environmental conditions remains poorly understood. In this study, we demonstrate that ATM is required for the maintenance of meiotic genome stability under heat stress in Arabidopsis thaliana. Using cytogenetic approaches we determined that ATM does not mediate reduced DSB formation but does ensure successful DSB repair, and thus meiotic chromosome integrity, under heat stress. Further genetic analysis suggested that ATM mediates DSB repair at high temperature by acting downstream of the MRE11-RAD50-NBS1 (MRN) complex, and acts in a RAD51-independent but chromosome axis-dependent manner. This study extends our understanding on the role of ATM in DSB repair and the protection of genome stability in plants under high temperature stress.

Expression analysis of TLR signaling pathway genes under lipopolysaccharide-induced and E. coli F17-infected sheep intestinal epithelial cells.

Escherichia coli (E. coli) F17 is one of the main pathogens causing diarrhea in young livestock. The specific F17 fimbriae and lipopolysaccharide (LPS) in the surface components of E. coli F17 induces immune activation via interacting with the intestinal epithelial cells (IECs)-expressed innate immune toll-like receptors (TLRs) signaling pathway. In this study, the expression patterns of eight canonical genes from the TLR signaling pathway (IL-6, IL-8, IL-1ß, TLR4, MyD88, CD14, TNF-α and TRAF6) were analyzed in LPS-induced IECs, E. coli F17-infected IECs and ileum tissue of E. coli F17-infected lambs. The results showed that increased expression levels of all the studied genes were observed following post-LPS-induced and E. coli F17-infected treatment, with TLR4 having the highest up-regulated expression multiple (compared to NC, fold change = 17.94 and 20.11, respectively), and CD14 having the lowest up-regulated expression multiple (fold change = 2.68 and 1.59, respectively), and higher expression levels of all the studied TLR signaling pathway genes were observed in ileum tissue of E. coli F17 antagonistic (AN) lambs than in E. coli F17 sensitive (SE) lambs. Furthermore, when compared to LPS-induced IECs, E. coli F17-infected IECs showed a more pronounced increase in the expression of IL6, TLR4 and TNF-α, indicating the different roles of these genes in the IECs resistance to E. coli F17 infection. Our results demonstrate that the TLR signaling pathway likely promotes immune activation and provide the first evidence that TLRs have a significant potential to protect against E. coli F17 infections.

Meroterpenoids and Steroids from the Marine-Derived Fungus Trametes sp. ZYX-Z-16.

Marine fungi can metabolize structurally diverse active components, and have become an important source of drug lead molecules. In the present study, the chemical investigation on the EtOAc extract of the fermentation broth of the marine-derived fungus Trametes sp. ZYX-Z-16 led to the isolation of eight meroterpenoids (1-8), including two undescribed ones, together with ten ergostane steroid analogues (9-18). The structures of two new spiromeroterpenoids, asnovolin H (1) and asnovolin I (2), were determined based on 1D, 2D NMR, and HRESIMS spectroscopic data along with ECD spectra calculations. All compounds were tested for antibacterial and α-glucosidase inhibitory activity. Among them, compound 12 showed definite antibacterial activities against Staphylococcus aureus ATCC 6538 (MIC 32 µg/mL) and Bacillus subtilis ATCC 6633 (MIC 16 µg/mL). In addition, compounds 9 and 10 showed superior inhibitory activity, with IC50 values of 104.1 and 111.3 µM, respectively, to the positive control acarbose (304.6 µM).

Emotional-Health-Oriented Urban Design: A Novel Collaborative Deep Learning Framework for Real-Time Landscape Assessment by Integrating Facial Expression Recognition and Pixel-Level Semantic Segmentation.

Emotional responses are significant for understanding public perceptions of urban green space (UGS) and can be used to inform proposals for optimal urban design strategies to enhance public emotional health in the times of COVID-19. However, most empirical studies fail to consider emotion-oriented landscape assessments under dynamic perspectives despite the fact that individually observed sceneries alter with angle. To close this gap, a real-time sentimental-based landscape assessment framework is developed, integrating facial expression recognition with semantic segmentation of changing landscapes. Furthermore, a case study using panoramic videos converted from Google Street View images to simulate changing scenes was used to test the viability of this framework, resulting in five million big data points. The result of this study shows that through the collaboration of deep learning algorithms, finer visual variables were classified, subtle emotional responses were tracked, and better regression results for valence and arousal were obtained. Among all the predictors, the proportion of grass was the most significant predictor for emotional perception. The proposed framework is adaptable and human-centric, and it enables the instantaneous emotional perception of the built environment by the general public as a feedback survey tool to aid urban planners in creating UGS that promote emotional well-being.

Comparative transcriptome and metabolome analyses identified the mode of sucrose degradation as a metabolic marker for early vegetative propagation in bulbs of Lycoris.

Vegetative propagation (VP) is an important practice for production in many horticultural plants. Sugar supply constitutes the basis of VP in bulb flowers, but the underlying molecular basis remains elusive. By performing a combined sequencing technologies coupled with ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry approach for metabolic analyses, we compared two Lycoris species with contrasting regeneration rates: high-regeneration Lycoris sprengeri and low-regeneration Lycoris aurea. A comprehensive multi-omics analyses identified both expected processes involving carbohydrate metabolism and transcription factor networks, as well as the metabolic characteristics for each developmental stage. A higher abundance of the differentially expressed genes including those encoding ethylene responsive factors was detected at bulblet initiation stage compared to the late stage of bulblet development. High hexose-to-sucrose ratio correlated to bulblet formation across all the species examined, indicating its role in the VP process in Lycoris bulb. Importantly, a clear difference between cell wall invertase (CWIN)-catalyzed sucrose unloading in high-regeneration species and the sucrose synthase-catalyzed pathway in low-regeneration species was observed at the bulblet initiation stage, which was supported by findings from carboxyfluorescein tracing and quantitative real-time PCR analyses. Collectively, the findings indicate a sugar-mediated model of the regulation of VP in which high CWIN expression or activity may promote bulblet initiation via enhancing apoplasmic unloading of sucrose or sugar signals, whereas the subsequent high ratio of hexose-to-sucrose likely supports cell division characterized in the next phase of bulblet formation.

Insights Into Long Non-Coding RNA and mRNA Expression in the Jejunum of Lambs Challenged With Escherichia coli F17.

It has long been recognized that enterotoxigenic Escherichia coli (ETEC) is the major pathogen responsible for vomiting and diarrhea. E. coli F17, a main subtype of ETEC, is characterized by high morbidity and mortality in young livestock. However, the transcriptomic basis underlying E. coli F17 infection has not been fully understood. In the present study, RNA sequencing was conducted to explore the expression profiles of mRNAs and long non-coding RNAs (lncRNAs) in the jejunum of lambs who were identified as resistant or sensitive to E. coli F17 that was obtained in a challenge experiment. A total of 772 differentially expressed (DE) mRNAs and 190 DE lncRNAs were detected between the E. coli F17-resistance and E. coli F17-sensitive lambs (i.e., TFF2, LOC105606142, OLFM4, LYPD8, REG4, APOA4, TCONS_00223467, and TCONS_00241897). Then, a two-step machine learning approach (RX) combination Random Forest and Extreme Gradient Boosting were performed, which identified 16 mRNAs and 17 lncRNAs as potential biomarkers, within which PPP2R3A and TCONS_00182693 were prioritized as key biomarkers involved in E. coli F17 infection. Furthermore, functional enrichment analysis showed that peroxisome proliferator-activated receptor (PPAR) pathway was significantly enriched in response to E. coli F17 infection. Our finding will help to improve the knowledge of the mechanisms underlying E. coli F17 infection and may provide novel targets for future treatment of E. coli F17 infection.

Integrative Comparative Assessment of Cold Acclimation in Evergreen and Deciduous Iris Species.

Cold acclimation (CA) is a strategy which plants have evolved to increase freezing tolerance. Global climate change could obstruct CA and raise the probability of winter injury, especially for evergreens. Hence, understanding the regulatory mechanism of CA is crucial to improve freezing tolerance in evergreen plants. A comparative study on a pair of closely related evergreen and deciduous iris species in response to cold through CA was conducive to uncovering and complementing the knowledge of CA. We investigated morphological, physiological and biochemical changes, as well as the expression of associated genes in the functional leaves of both iris species from natural CA to deacclimation. Briefly, fast and strong CA in the evergreen iris might cause early expressions of BAM1, NCED3, GPX6, etc., which leads to strong enzyme activity of starch degradation, abscisic acid biosynthesis and reactive oxygen species scavenging. Additionally, genes belonging to the antioxidant system were mainly induced during deacclimation. These results suggest that interspecies differences in the leaf freezing tolerance of irises are associated with the rate and degree of CA, which activates multiple signaling networks with complex interactions and induces the transcription of cold-responsive genes. Moreover, the ICE-CBF-COR signaling cascade may integrate and initiate diverse cold-responsive pathways during CA of the evergreen iris. The findings of this study provide valuable insight to further research on CA mechanisms and implicate genes which could support breeding strategies in herbaceous perennials under climate changes.

Effects of di-n-butyl phthalate on aerobic composting process of agricultural waste: Mainly based on bacterial biomass and community dynamics analysis.

Phthalic acid esters (PAEs) pollution has become a major environmental problem in agricultural waste composting. However, little information was available about the how the PAEs alter microbial processes during composting. This study investigated the effects of di-n-butyl phthalate (DBP) on bacterial biomass and community dynamics during composting. The results showed that a decreasing of DBP was observed from thermophilic phase and 43.26% of DBP was degraded after composting. The bacterial biomass and diversity during composting were reduced under DBP stress, so delaying the decomposition of organic matter. Moreover, the changes in bacterial community were observed since the thermophilic phase of DBP-contaminated composting. KEGG pathway analysis indicated that DBP stress decreased the relative abundance of the main metabolic pathways and inhibited compost maturation. Moreover, DBP stress had more significant correlation with the dominant bacteria. This work will expand the understanding of PAEs-contaminated organic waste composting and further control of PAEs pollutants.

A Compact Optical MEMS Pressure Sensor Based on Fabry-Pérot Interference.

Pressure sensors have important prospects in wind pressure monitoring of transmission line towers. Optical pressure sensors are more suitable for transmission line towers due to its anti-electromagnetic interference. However, the fiber pressure sensor is not a suitable choice due to expensive and bulky. In this paper, a compact optical Fabry-Pérot (FP) pressure sensor for wind pressure measurement was developed by MEMS technology. The pressure sensor consists of a MEMS sensing chip, a vertical-cavity surface-emitting laser (Vcsel), and a photodiode (PD). The sensing chip is combined with an FP cavity and a pressure sensing diaphragm which adopts the square film and is fabricated by Silicon on Insulator (SOI) wafer. To calibrate the pressure sensor, the experimental platform which consists of a digital pressure gauge, a pressure loading machine, a digital multimeter, and a laser driver was set up. The experimental results show that the sensitivity of the diaphragm is 117.5 nm/kPa. The measurement range and sensitivity of the pressure sensor are 0-700 Pa and 115 nA/kPa, respectively. The nonlinearity, repeatability, and hysteresis of the pressure sensor are 1.48%FS, 2.23%FS, and 1.59%FS, respectively, which lead to the pressure accuracy of 3.12%FS.

Non-Coding Transcriptome Provides Novel Insights into the Escherichia coli F17 Susceptibility of Sheep Lamb.

It has long been recognized that enterotoxigenic Escherichia coli (ETEC) is the major pathogen responsible for vomiting and diarrhea. E. coli F17, a main subtype of ETEC, is characterized by high morbidity and mortality in young livestock. However, the transcriptomic basis underlying E. coli F17 infection has not been fully understood. In this study, RNA sequencing was performed to explore the expression profiles of circRNAs and miRNAs in the jejunum of E. coli F17-antagonism (AN) and -sensitive (SE) lambs. A total of 16,534 circRNAs and 271 miRNAs (125 novel miRNAs and 146 annotated miRNAs) were screened, and 214 differentially expressed (DE) circRNAs and 53 DE miRNAs were detected between the AN and SE lambs (i.e., novel_circ_0025840, novel_circ_0022779, novel_miR_107, miR-10b). Functional enrichment analyses showed that source genes of DE circRNAs were mainly involved in metabolic-related pathways, while target genes of DE miRNAs were mainly enriched in the immune response pathways. Then, a two-step machine learning approach combining Random Forest (RF) and XGBoost (candidates were first selected by RF and further assessed by XGBoost) was performed, which identified 44 circRNAs and 39 miRNAs as potential biomarkers (i.e., novel_circ_0000180, novel_circ_0000365, novel_miR_192, oar-miR-496-3p) for E. coli infection. Furthermore, circRNA-related and lncRNA-related ceRNA networks were constructed, containing 46 circRNA-miRNA-mRNA competing triplets and 630 lncRNA-miRNA-mRNA competing triplets, respectively. By conducting a serious of bioinformatic analyses, our results revealed important circRNAs and miRNAs that could be potentially developed as candidate biomarkers for intestinal inflammatory response against E. coli F17 infection; our study can provide novel insights into the underlying mechanisms of intestinal immunity.

Interfered chromosome pairing at high temperature promotes meiotic instability in autotetraploid Arabidopsis.

Changes in environmental temperature affect multiple meiotic processes in flowering plants. Polyploid plants derived from whole-genome duplication (WGD) have enhanced genetic plasticity and tolerance to environmental stress but face challenges in organizing and segregating doubled chromosome sets. In this study, we investigated the impact of increased environmental temperature on male meiosis in autotetraploid Arabidopsis (Arabidopsis thaliana). Under low to mildly increased temperatures (5°C-28°C), irregular chromosome segregation universally occurred in synthetic autotetraploid Columbia-0 (Col-0). Similar meiotic lesions occurred in autotetraploid rice (Oryza sativa L.) and allotetraploid canola (Brassica napus cv Westar), but not in evolutionarily derived hexaploid wheat (Triticum aestivum). At extremely high temperatures, chromosome separation and tetrad formation became severely disordered due to univalent formation caused by the suppression of crossing-over. We found a strong correlation between tetravalent formation and successful chromosome pairing, both of which were negatively correlated with temperature elevation, suggesting that increased temperature interferes with crossing-over predominantly by impacting homolog pairing. We also showed that loading irregularities of axis proteins ASY1 and ASY4 co-localize on the chromosomes of the syn1 mutant and the heat-stressed diploid and autotetraploid Col-0, revealing that heat stress affects the lateral region of synaptonemal complex (SC) by impacting the stability of the chromosome axis. Moreover, we showed that chromosome axis and SC in autotetraploid Col-0 are more sensitive to increased temperature than those in diploid Arabidopsis. Taken together, our data provide evidence suggesting that WGD negatively affects the stability and thermal tolerance of meiotic recombination in newly synthetic autotetraploid Arabidopsis.

Early Sucrose Degradation and the Dominant Sucrose Cleavage Pattern Influence Lycoris sprengeri Bulblet Regeneration In Vitro.

Bulblet formation and development determine the quantitative and qualitative traits, respectively, of bulb yield for most flowering bulbs. For Lycoris species, however, the underlying molecular mechanism remains elusive. Here, clonal bulblets of Lycoris sprengeri (Ls) derived from the same probulb were used as explants to establish efficient and inefficient in vitro regeneration systems by adjusting the 6-benzyladenine (BA) concentrations in media. BA application did not change the biological processes among groups but led to earlier decreases in sucrose and total soluble sugar (TSS) contents. Correlation analyses showed that the BA treatments changed the interaction between carbohydrate and endogenous hormone contents during bulblet regeneration. We found that two sucrose degradation enzyme-related genes, cell wall invertase (CWIN) and sucrose synthase, exhibited exactly opposite expression patterns during the competence stage. In addition, the regeneration system that obtained more bulblets showed significantly higher expression of LsCWIN2 than those that obtained fewer bulblets. Our data demonstrate the essential role of BA in accelerating sucrose degradation and the selection of a dominant sucrose cleavage pattern at the competence stage of in vitro bulblet regeneration. We propose that a relatively active CWIN-catalyzed pathway at the competence stage might promote bulblet regeneration, thus influencing bulb yield.

Robot-aided fN∙m torque sensing within an ultrawide dynamic range.

In situ scanning electron microscope (SEM) characterization have enabled the stretching, compression, and bending of micro/nanomaterials and have greatly expanded our understanding of small-scale phenomena. However, as one of the fundamental approaches for material analytics, torsion tests at a small scale remain a major challenge due to the lack of an ultrahigh precise torque sensor and the delicate sample assembly strategy. Herein, we present a microelectromechanical resonant torque sensor with an ultrahigh resolution of up to 4.78 fN∙m within an ultrawide dynamic range of 123 dB. Moreover, we propose a nanorobotic system to realize the precise assembly of microscale specimens with nanoscale positioning accuracy and to conduct repeatable in situ pure torsion tests for the first time. As a demonstration, we characterized the mechanical properties of Si microbeams through torsion tests and found that these microbeams were five-fold stronger than their bulk counterparts. The proposed torsion characterization system pushes the limit of mechanical torsion tests, overcomes the deficiencies in current in situ characterization techniques, and expands our knowledge regarding the behavior of micro/nanomaterials at various loads, which is expected to have significant implications for the eventual development and implementation of materials science.

Molecular cloning, characterization and expression analysis of three key starch synthesis-related genes from the bulb of a rare lily germplasm, Lilium brownii var. giganteum.

Starch is the predominant compound in bulb scales, and previous studies have shown that bulblet development is closely associated with starch enrichment. However, how starch synthesis affects bulbification at the molecular level is unclear. In this study, we demonstrate that Lilium brownii var. giganteum, a wild lily with a giant bulb in nature, and L. brownii, the native species, have different starch levels and characteristics according to cytological and ultra-structural observations. We cloned the complete sequence of three key gene-encoding enzymes (LbgAGPS, LbgGBSS, andLbgSSIII) during starch synthesis by rapid amplification of 5' and 3' complementary DNA (cDNA) ends (RACE) technology. Bioinformatics analysis revealed that the proteins deduced by these genes contain the canonical conserved domains. Constructed phylogenetic trees confirmed the evolutionary relationships with proteins from other species, including monocotyledons and dicotyledons. The transcript levels of various tissues and time course samples obtained during bulblet development uncovered relatively high expression levels in bulblets and gradual increase expression accompanying bulblet growth. Moreover, a set of single nucleotide polymorphisms (SNPs) was discovered in the AGPS genes of four lily genotypes, and a purifying selection fashion was predicted according to the non-synonymous/synonymous (Ka/Ks) values. Taken together, our results suggested that key starch-synthesizing genes might play important roles in bulblet development and lead to distinctive phenotypes in bulblet size.

Change in Sucrose Cleavage Pattern and Rapid Starch Accumulation Govern Lily Shoot-to-Bulblet Transition in vitro.

In bulb crops, bulbing is a key progress in micropropagation and is the feature that most distinguishes bulbous crops from other plants. Generally, bulbing involves a shoot-to-bulblet transition; however, the underlying mechanism remains elusive. We explored this process by tracking the shoot-to-bulblet transition under different culture conditions. Rapid starch accumulation occurred at 15 days after transplanting (DAT) in the bulblet-inducing treatments as confirmed via histological observations and the significant elevation of starch synthesis related-gene transcription, including LohAGPS, LohAGPL, LohGBSS, LohSS, and LohSBE. However, for shoots that did not transition to bulblets and maintained the shoot status, much higher soluble sugars were detected. Interestingly, we observed a clear shift from invertase-catalyzed to sucrose synthase-catalyzed sucrose cleavage pattern based on the differential expression of LohCWIN and LohSuSy during the key transition stage (prior to and after bulbing at 0-15 DAT). Shoots that transitioned into bulblets showed significantly higher LohSuSy expression, especially LohSuSy4 expression, than shoots that did not transition. A symplastic phloem unloading pathway at the bulblet emergence stage (15 DAT) was verified via the 6(5)-carboxyfluorescein diacetate fluorescent tracer. We propose that starch is the fundamental compound in the shoot-to-bulblet transition and that starch synthesis is likely triggered by the switch from apoplastic to symplastic sucrose unloading, which may be related to sucrose depletion. Furthermore, this study is the first to provide a complete inventory of the genes involved in starch metabolism based on our transcriptome data. Two of these genes, LohAGPS1.2b and LohSSIIId, were verified by rapid amplification of cDNA ends cloning, and these data will provide additional support for Lilium research since whole genome is currently lacking.

Design and Fabrication of Micro Hemispheric Shell Resonator with Annular Electrodes.

Electrostatic driving and capacitive detection is widely used in micro hemispheric shell resonators (HSR). The capacitor gap distance is a dominant factor for the initial capacitance, and affects the driving voltage and sensitivity. In order to decrease the equivalent gap distance, a micro HSR with annular electrodes fabricated by a glassblowing method was developed. Central and annular cavities are defined, and then the inside gas drives glass softening and deformation at 770 °C. While the same force is applied, the deformation of the hemispherical shell is about 200 times that of the annular electrodes, illustrating that the deformation of the electrodes will not affect the measurement accuracy. S-shaped patterns on the annular electrodes and internal-gear-like patterns on the hemispherical shell can improve metal malleability and avoid metal cracking during glass expansion. An arched annular electrode and a hemispheric shell are demonstrated. Compared with HSR with a spherical electrode, the applied voltage could be reduced by 29%, and the capacitance could be increased by 39%, according to theoretical and numerical calculation. The surface roughness of glass after glassblowing was favorable (Rq = 0.296 nm, Ra = 0.217 nm). In brief, micro HSR with an annular electrode was fabricated, and its superiority was preliminarily confirmed.