A feedback regulation of FgHtf1-FgCon7 loop in conidiogenesis and development of Fusarium graminearum

The transcription factor FgHtf1 is important for conidiogenesis in Fusarium graminearum and it positively regulates the expression of the sporulation-related gene FgCON7. However, the regulatory mechanism underlying its functions is still unclear. The present study intends to uncover the functional mechanism of FgHtf1 in relation to FgCon7 in F. graminearum. We demonstrated that FgCON7 serves as a target gene for FgHtf1. Interestingly, FgCon7 also binds the promoter region of FgHTF1 to negatively regulate its expression, thus forming a negative-feedback loop. We demonstrated that FgHtf1 and FgCon7 have functional redundancy in fungal development. FgCon7 localizes in the nucleus and has transcriptional activation activity. Deletion of FgCON7 significantly reduces conidia production. 4444 genes were regulated by FgCon7 in ChIP-Seq, and RNA-Seq revealed 4430 differentially expressed genes in FgCON7 deletion mutant, with CCAAT serving as a consensus binding motif of FgCon7 to the target genes. FgCon7 directly binds the promoter regions of FgMSN2, FgABAA, FgVEA and FgSMT3 genes and regulates their expression. These genes were found to be important for conidiogenesis. To our knowledge, this is the first study that unveiled the mutual regulatory functions of FgCON7 and FgHTF1 to form a negative-feedback loop, and how the loop mediates sporulation in F. graminearum.

BCL7A and BCL7B potentiate SWI/SNF-complex-mediated chromatin accessibility to regulate gene expression and vegetative phase transition in plants

Switch defective/sucrose non-fermentable (SWI/SNF) chromatin remodeling complexes are multi-subunit machineries that establish and maintain chromatin accessibility and gene expression by regulating chromatin structure. However, how the remodeling activities of SWI/SNF complexes are regulated in eukaryotes remains elusive. B-cell lymphoma/leukemia protein 7 A/B/C (BCL7A/B/C) have been reported as subunits of SWI/SNF complexes for decades in animals and recently in plants; however, the role of BCL7 subunits in SWI/SNF function remains undefined. Here, we identify a unique role for plant BCL7A and BCL7B homologous subunits in potentiating the genome-wide chromatin remodeling activities of SWI/SNF complexes in plants. BCL7A/B require the catalytic ATPase BRAHMA (BRM) to assemble with the signature subunits of the BRM-Associated SWI/SNF complexes (BAS) and for genomic binding at a subset of target genes. Loss of BCL7A and BCL7B diminishes BAS-mediated genome-wide chromatin accessibility without changing the stability and genomic targeting of the BAS complex, highlighting the specialized role of BCL7A/B in regulating remodeling activity. We further show that BCL7A/B fine-tune the remodeling activity of BAS complexes to generate accessible chromatin at the juvenility resetting region (JRR) of the microRNAs MIR156A/C for plant juvenile identity maintenance. In summary, our work uncovers the function of previously elusive SWI/SNF subunits in multicellular eukaryotes and provides insights into the mechanisms whereby plants memorize the juvenile identity through SWI/SNF-mediated control of chromatin accessibility.

Origin and evolution of the triploid cultivated banana genome

Most fresh bananas belong to the Cavendish and Gros Michel subgroups. Here, we report chromosome-scale genome assemblies of Cavendish (1.48 Gb) and Gros Michel (1.33 Gb), defining three subgenomes, Ban, Dh and Ze, with Musa acuminata ssp. banksii, malaccensis and zebrina as their major ancestral contributors, respectively. The insertion of repeat sequences in the Fusarium oxysporum f. sp. cubense (Foc) tropical race 4 RGA2 (resistance gene analog 2) promoter was identified in most diploid and triploid bananas. We found that the receptor-like protein (RLP) locus, including Foc race 1-resistant genes, is absent in the Gros Michel Ze subgenome. We identified two NAP (NAC-like, activated by apetala3/pistillata) transcription factor homologs specifically and highly expressed in fruit that directly bind to the promoters of many fruit ripening genes and may be key regulators of fruit ripening. Our genome data should facilitate the breeding and super-domestication of bananas.

Sea-ATI unravels novel vocabularies of plant active cistrome

The cistrome consists of all cis-acting regulatory elements recognized by transcription factors (TFs). However, only a portion of the cistrome is active for TF binding in a specific tissue. Resolving the active cistrome in plants remains challenging. In this study, we report the assay sequential extraction assisted-active TF identification (sea-ATI), a low-input method that profiles the DNA sequences recognized by TFs in a target tissue. We applied sea-ATI to seven plant tissues to survey their active cistrome and generated 41 motif models, including 15 new models that represent previously unidentified cis-regulatory vocabularies. ATAC-seq and RNA-seq analyses confirmed the functionality of the cis-elements from the new models, in that they are actively bound in vivo, located near the transcription start site, and influence chromatin accessibility and transcription. Furthermore, comparing dimeric WRKY CREs between sea-ATI and DAP-seq libraries revealed that thermodynamics and genetic drifts cooperatively shaped their evolution. Notably, sea-ATI can identify not only positive but also negative regulatory cis-elements, thereby providing unique insights into the functional non-coding genome of plants.

Low temperature-induced regulatory network rewiring via WRKY regulators during banana peel browning

Banana (Musa spp.) fruits, as typical tropical fruits, are cold sensitive, and lower temperatures can disrupt cellular compartmentalization and lead to severe browning. How tropical fruits respond to low temperature compared to the cold response mechanisms of model plants remains unknown. Here, we systematically characterized the changes in chromatin accessibility, histone modifications, distal cis-regulatory elements, transcription factor binding, and gene expression levels in banana peels in response to low temperature. Dynamic patterns of cold-induced transcripts were generally accompanied by concordant chromatin accessibility and histone modification changes. These upregulated genes were enriched for WRKY binding sites in their promoters and/or active enhancers. Compared to banana peel at room temperature, large amounts of banana WRKYs were specifically induced by cold and mediated enhancer-promoter interactions regulating critical browning pathways, including phospholipid degradation, oxidation, and cold tolerance. This hypothesis was supported by DNA affinity purification sequencing, luciferase reporter assays, and transient expression assay. Together, our findings highlight widespread transcriptional reprogramming via WRKYs during banana peel browning at low temperature and provide an extensive resource for studying gene regulation in tropical plants in response to cold stress, as well as potential targets for improving cold tolerance and shelf life of tropical fruits.

The NAC transcription factors SNAP1/2/3/4 are central regulators mediating high nitrogen responses in mature nodules of soybean

Legumes can utilize atmospheric nitrogen via symbiotic nitrogen fixation, but this process is inhibited by high soil inorganic nitrogen. So far, how high nitrogen inhibits N2 fixation in mature nodules is still poorly understood. Here we construct a co-expression network in soybean nodule and find that a dynamic and reversible transcriptional network underlies the high N inhibition of N2 fixation. Intriguingly, several NAC transcription factors (TFs), designated as Soybean Nitrogen Associated NAPs (SNAPs), are amongst the most connected hub TFs. The nodules of snap1/2/3/4 quadruple mutants show less sensitivity to the high nitrogen inhibition of nitrogenase activity and acceleration of senescence. Integrative analysis shows that these SNAP TFs largely influence the high nitrogen transcriptional response through direct regulation of a subnetwork of senescence-associated genes and transcriptional regulators. We propose that the SNAP-mediated transcriptional network may trigger nodule senescence in response to high nitrogen.

Characterization of Banana SNARE Genes and Their Expression Analysis under Temperature Stress and Mutualistic and Pathogenic Fungal Colonization

SNAREs (soluble N-ethylmaleimide-sensitive-factor attachment protein receptors) are engines for almost all of the membrane fusion and exocytosis events in organism cells. In this study, we identified 84 SNARE genes from banana (Musa acuminata). Gene expression analysis revealed that the expression of MaSNAREs varied a lot in different banana organs. By analyzing their expression patterns under low temperature (4 °C), high temperature (45 °C), mutualistic fungus (Serendipita indica, Si) and fungal pathogen (Fusarium oxysporum f. sp. Cubense Tropical Race 4, FocTR4) treatments, many MaSNAREs were found to be stress responsive. For example, MaBET1d was up-regulate by both low and high temperature stresses; MaNPSN11a was up-regulated by low temperature but down-regulated by high temperature; and FocTR4 treatment up-regulated the expression of MaSYP121 but down-regulated MaVAMP72a and MaSNAP33a. Notably, the upregulation or downregulation effects of FocTR4 on the expression of some MaSNAREs could be alleviated by priorly colonized Si, suggesting that they play roles in the Si-enhanced banana wilt resistance. Foc resistance assays were performed in tobacco leaves transiently overexpressing MaSYP121, MaVAMP72a and MaSNAP33a. Results showed that transient overexpression of MaSYP121 and MaSNPA33a suppressed the penetration and spread of both Foc1 (Foc Race 1) and FocTR4 in tobacco leaves, suggesting that they play positive roles in resisting Foc infection. However, the transient overexpression of MaVAMP72a facilitated Foc infection. Our study can provide a basis for understanding the roles of MaSNAREs in the banana responses to temperature stress and mutualistic and pathogenic fungal colonization.

Integrated metabolic, transcriptomic and chromatin accessibility analyses provide novel insights into the competition for anthocyanins and flavonols biosynthesis during fruit ripening in red apple

Fruit ripening is accompanied by a wide range of metabolites and global changes in gene expression that are regulated by various factors. In this study, we investigated the molecular differences in red apple 'Hongmantang' fruits at three ripening stages (PS1, PS5 and PS9) through a comprehensive analysis of metabolome, transcriptome and chromatin accessibility. Totally, we identified 341 and 195 differentially accumulated metabolites (DAMs) in comparison I (PS5_vs_PS1) and comparison II (PS9_vs_PS5), including 57 and 23 differentially accumulated flavonoids (DAFs), respectively. Intriguingly, among these DAFs, anthocyanins and flavonols showed opposite patterns of variation, suggesting a possible competition between their biosynthesis. To unveil the underlying mechanisms, RNA-Seq and ATAC-Seq analyses were performed. A total of 852 DEGs significantly enriched in anthocyanin metabolism and 128 differential accessible regions (DARs) significantly enriched by MYB-related motifs were identified as up-regulated in Comparison I but down-regulated in Comparison II. Meanwhile, the 843 DEGs significantly enriched in phenylalanine metabolism and the 364 DARs significantly enriched by bZIP-related motifs showed opposite trends. In addition, four bZIPs and 14 MYBs were identified as possible hub genes regulating the biosynthesis of flavonols and anthocyanins. Our study will contribute to the understanding of anthocyanins and flavonols biosynthesis competition in red apple fruits during ripening.

The OsFTIP6-OsHB22-OsMYBR57 module regulates drought response in rice

Plants have evolved a sophisticated set of mechanisms to adapt to drought stress. Transcription factors play crucial roles in plant responses to various environmental stimuli by modulating the expression of numerous stress-responsive genes. However, how the crosstalk between different transcription factor families orchestrates initiation of the key transcriptional network and the role of posttranscriptional modification of transcription factors, especially in cellular localization/trafficking in response to stress in rice, remain still largely unknown. In this study, we isolated an Osmybr57 mutant that displays a drought-sensitive phenotype through a genetic screen for drought stress sensitivity. We found that OsMYBR57, an MYB-related protein, directly regulates the expression of several key drought-related OsbZIPs in response to drought treatment. Further studies revealed that OsMYBR57 interacts with a homeodomain transcription factor, OsHB22, which also plays a positive role in drought signaling. We further demonstrate that OsFTIP6 interacts with OsHB22 and promotes the nucleocytoplasmic translocation of OsHB22 into the nucleus, where OsHB22 cooperates with OsMYBR57 to regulate the expression of drought-responsive genes. Our findings have revealed a mechanistic framework underlying the OsFTIP6-OsHB22-OsMYBR57 module-mediated regulation of drought response in rice. The OsFTIP6-mediated OsHB22 nucleocytoplasmic shuttling and OsMYBR57-OsHB22 regulation of OsbZIP transcription ensure precise control of expression of OsLEA3 and Rab21, and thereby regulate the response to water deficiency in rice.

Ethylene response factor MdERF4 and histone deacetylase MdHDA19 suppress apple fruit ripening through histone deacetylation of ripening-related genes

Histone deacetylase enzymes participate in the regulation of many aspects of plant development. However, the genome-level targets of histone deacetylation during apple (Malus domestica) fruit development have not been resolved in detail, and the mechanisms of regulation of such a process are unknown. We previously showed that the complex of ethylene response factor 4 (MdERF4) and the TOPLESS co-repressor (MdTPL4; MdERF4-MdTPL4) is constitutively active during apple fruit development (Hu et al., 2020), but whether this transcriptional repression complex is coupled to chromatin modification is unknown. Here, we show that a histone deacetylase (MdHDA19) is recruited to the MdERF4-MdTPL4 complex, thereby impacting fruit ethylene biosynthesis. Transient suppression of MdHDA19 expression promoted fruit ripening and ethylene production. To identify potential downstream target genes regulated by MdHDA19, we conducted chromatin immunoprecipitation (ChIP) sequencing of H3K9 and ChIP-quantitative polymerase chain reaction assays. We found that MdHDA19 affects ethylene production by facilitating H3K9 deacetylation and forms a complex with MdERF4-MdTPL4 to directly repress MdACS3a expression by decreasing the degree of acetylation. We demonstrate that an early-maturing-specific acetylation H3K9ac peak in MdACS3a and expression of MdACS3a were specifically up-regulated in fruit of an early-maturing, but not a late-maturing, cultivar. We provide evidence that a C-to-G mutation in the ethylene-responsive element binding factor-associated amphiphilic repression motif of MdERF4 reduces the repression of MdACS3a by the MdERF4-MdTPL4-MdHDA19 complex. Taken together, our results reveal that the MdERF4-MdTPL-MdHDA19 repressor complex participates in the epigenetic regulation of apple fruit ripening.

Identification of Chilling Accumulation-Associated Genes for Litchi Flowering by Transcriptome-Based Genome-Wide Association Studies

Litchi is an important Sapindaceae fruit tree. Flowering in litchi is triggered by low temperatures in autumn and winter. It can be divided into early-, medium-, and late-flowering phenotypes according to the time for floral induction. Early-flowering varieties need low chilling accumulation level for floral induction, whereas the late-flowering varieties require high chilling accumulation level. In the present study, RNA-Seq of 87 accessions was performed and transcriptome-based genome-wide association studies (GWAS) was used to identify candidate genes involved in chilling accumulation underlying the time for floral induction. A total of 98,155 high-quality single-nucleotide polymorphism (SNP) sites were obtained. A total of 1,411 significantly associated SNPs and 1,115 associated genes (AGs) were identified, of which 31 were flowering-related, 23 were hormone synthesis-related, and 27 were hormone signal transduction-related. Association analysis between the gene expression of the AGs and the flowering phenotypic data was carried out, and differentially expressed genes (DEGs) in a temperature-controlled experiment were obtained. As a result, 15 flowering-related candidate AGs (CAGs), 13 hormone synthesis-related CAGs, and 11 hormone signal transduction-related CAGs were further screened. The expression levels of the CAGs in the early-flowering accessions were different from those in the late-flowering ones, and also between the flowering trees and non-flowering trees. In a gradient chilling treatment, flowering rates of the trees and the CAGs expression were affected by the treatment. Our present work for the first time provided candidate genes for genetic regulation of flowering in litchi using transcriptome-based GWAS.

Genome-wide identification of FAD gene family and their contributions to the temperature stresses and mutualistic and parasitic fungi colonization responses in banana

Fatty acid desaturase (FAD) plays important roles in plant growth and development and plant defense processes. In this study, we identified 27 MaFAD genes from the banana genome. According to the amino acid sequence similarities, their encoded proteins could be classified into five subfamilies. This classification is consistently supported by their gene and protein structures, conserved motifs and subcellular localizations. Segmental duplication events were found to play predominant roles in the MaFAD gene family expansion. Thirty miRNAs targeting MaFADs were identified and many hormone- and stress-responsive cis-acting elements and transcription factor binding sites (TFBSs) were identified in their promoters, indicating that the MaFADs expression regulation was very complicated. Gene expression analysis showed that some MaFADs showed significant differential expression in response to high and low temperature. FocTR4 influenced greatly the expression of several MaFADs and greatly induced the fatty acid (FA) accumulations in roots. Although S. indica showed no significant influence on the expression of most MaFADs, it could greatly alleviate the influence of FocTR4 on several MaFADs and FA biosynthesis. Our study revealed that MaFADs contributed greatly to the responses of high and low temperature stresses and mutualistic and parasitic fungi colonization in banana.

Regulation of rose petal dehydration tolerance and senescence by RhNAP transcription factor via the modulation of cytokinin catabolism

Petals and leaves share common evolutionary origins but have different phenotypic characteristics, such as the absence of stomata in the petals of most angiosperm species. Plant NAC transcription factor, NAP, is involved in ABA responses and regulates senescence-associated genes, and especially those that affect stomatal movement. However, the regulatory mechanisms and significance of NAP action in senescing astomatous petals is unclear. A major limiting factor is failure of flower opening and accelerated senescence. Our goal is to understand the finely regulatory mechanism of dehydration tolerance and aging in rose flowers. We functionally characterized RhNAP, an AtNAP-like transcription factor gene that is induced by dehydration and aging in astomatous rose petals. Cytokinins (CKs) are known to delay petal senescence and we found that a cytokinin oxidase/dehydrogenase gene 6 (RhCKX6) shares similar expression patterns with RhNAP. Silencing of RhNAP or RhCKX6 expression in rose petals by virus induced gene silencing markedly reduced petal dehydration tolerance and delayed petal senescence. Endogenous CK levels in RhNAP- or RhCKX6-silenced petals were significantly higher than those of the control. Moreover, RhCKX6 expression was reduced in RhNAP-silenced petals. This suggests that the expression of RhCKX6 is regulated by RhNAP. Yeast one-hybrid experiments and electrophoresis mobility shift assays showed that RhNAP binds to the RhCKX6 promoter in heterologous in vivo system and in vitro, respectively. Furthermore, the expression of putative signal transduction and downstream genes of ABA-signaling pathways were also reduced due to the repression of PP2C homolog genes by RhNAP in rose petals. Taken together, our study indicates that the RhNAP/RhCKX6 interaction represents a regulatory step enhancing dehydration tolerance in young rose petals and accelerating senescence in mature petals in a stomata-independent manner.

The RhHB1/RhLOX4 module affects the dehydration tolerance of rose flowers (Rosa hybrida) by fine-tuning jasmonic acid levels

Phytohormones are key factors in plant responsiveness to abiotic and biotic stresses, and maintaining hormone homeostasis is critically important during stress responses. Cut rose (Rosa hybrida) flowers experience dehydration stress during postharvest handling, and jasmonic acid (JA) levels change as a result of this stress. However, how JA is involved in dehydration tolerance remains unclear. We investigated the functions of the JA- and dehydration-induced RhHB1 gene, which encodes a homeodomain-leucine zipper I γ-clade transcription factor, in rose flowers. Silencing RhHB1 decreased petal dehydration tolerance and resulted in a persistent increase in JA-Ile content and reduced dehydration tolerance. An elevated JA-Ile level had a detrimental effect on rose petal dehydration tolerance. RhHB1 was shown to lower the transient induction of JA-Ile accumulation in response to dehydration. In addition to transcriptomic data, we obtained evidence that RhHB1 suppresses the expression of the lipoxygenase 4 (RhLOX4) gene by directly binding to its promoter both in vivo and in vitro. We propose that increased JA-Ile levels weaken the capacity for osmotic adjustment in petal cells, resulting in reduced dehydration tolerance. In conclusion, a JA feedback loop mediated by an RhHB1/RhLOX4 regulatory module provides dehydration tolerance by fine-tuning bioactive JA levels in dehydrated flowers.

Genome encode analyses reveal the basis of convergent evolution of fleshy fruit ripening

Fleshy fruits using ethylene to regulate ripening have developed multiple times in the history of angiosperms, presenting a clear case of convergent evolution whose molecular basis remains largely unknown. Analysis of the fruitENCODE data consisting of 361 transcriptome, 71 accessible chromatin, 147 histone and 45 DNA methylation profiles reveals three types of transcriptional feedback circuits controlling ethylene-dependent fruit ripening. These circuits are evolved from senescence or floral organ identity pathways in the ancestral angiosperms either by neofunctionalisation or repurposing pre-existing genes. The epigenome, H3K27me3 in particular, has played a conserved role in restricting ripening genes and their orthologues in dry and ethylene-independent fleshy fruits. Our findings suggest that evolution of ripening is constrained by limited hormone molecules and genetic and epigenetic materials, and whole-genome duplications have provided opportunities for plants to successfully circumvent these limitations.

Genome encode analyses reveal the basis of convergent evolution of fleshy fruit ripening

Fleshy fruits using ethylene to regulate ripening have developed multiple times in the history of angiosperms, presenting a clear case of convergent evolution whose molecular basis remains largely unknown. Analysis of the fruitENCODE data consisting of 361 transcriptome, 71 accessible chromatin, 147 histone and 45 DNA methylation profiles reveals three types of transcriptional feedback circuits controlling ethylene-dependent fruit ripening. These circuits are evolved from senescence or floral organ identity pathways in the ancestral angiosperms either by neofunctionalisation or repurposing pre-existing genes. The epigenome, H3K27me3 in particular, has played a conserved role in restricting ripening genes and their orthologues in dry and ethylene-independent fleshy fruits. Our findings suggest that evolution of ripening is constrained by limited hormone molecules and genetic and epigenetic materials, and whole-genome duplications have provided opportunities for plants to successfully circumvent these limitations.

[Relationship between the Change Rules of Volatile Organic Compounds in Rat Muscle and Postmortem Interval]

OBJECTIVES

To explore the relationship between the change rules of volatile organic compounds （VOCs） in rat muscle and postmortem interval （PMI）.

METHODS

A total of 120 healthy rats were divided randomly into 12 groups （10 for each group）. After the rats were sacrificed by cervical dislocation, the bodies were kept at （25±1） ℃. Rat muscle samples were separately obtained at 12 PMI points, including 0, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 d. The VOCs in rat muscles were collected, detected and analyzed by headspace solid-phase microextraction （HS-SPME） coupled to gas chromatography-mass spectrometer （GC-MS）.

RESULTS

In total, 15 species of VOCs were identified, including 9 aromatic compounds, 3 sulfur compounds, 2 aliphatic acids and 1 heterocyclic compound. The species of VOCs increased with PMI： no species were detected within 1 day, 3 species were detected on day 2, 9 on day 3, 11 on day 4, 14 from day 5 to 7, and 15 from day 8 to 10. Total peak area of 15 species of VOCs was significantly correlated to PMI （adjusted R²=0.15-0.96）： the regression function was y=-17.05 x²+ 164.36 x-246.36 （adjusted R²=0.96） from day 2 to 5, and y=2.24 x+101.13 （adjusted R²=0.97） from day 6 to 10.

CONCLUSIONS

The change rules of VOCs in rat muscle are helpful for PMI estimation.

3D Chromatin Architecture of Large Plant Genomes Determined by Local A/B Compartments

The spatial organization of the genome plays an important role in the regulation of gene expression. However, the core structural features of animal genomes, such as topologically associated domains (TADs) and chromatin loops, are not prominent in the extremely compact Arabidopsis genome. In this study, we examine the chromatin architecture, as well as their DNA methylation, histone modifications, accessible chromatin, and gene expression, of maize, tomato, sorghum, foxtail millet, and rice with genome sizes ranging from 0.4 to 2.4 Gb. We found that these plant genomes can be divided into mammalian-like A/B compartments. At higher resolution, the chromosomes of these plants can be further partitioned to local A/B compartments that reflect their euchromatin, heterochromatin, and polycomb status. Chromatins in all these plants are organized into domains that are not conserved across species. They show similarity to the Drosophila compartment domains, and are clustered into active, polycomb, repressive, and intermediate types based on their transcriptional activities and epigenetic signatures, with domain border overlaps with the local A/B compartment junctions. In the large maize and tomato genomes, we observed extensive chromatin loops. However, unlike the mammalian chromatin loops that are enriched at the TAD border, plant chromatin loops are often formed between gene islands outside the repressive domains and are closely associated with active compartments. Our study indicates that plants have complex and unique 3D chromatin architectures, which require further study to elucidate their biological functions.

Dusky works upstream of Four-jointed and Forked in wing morphogenesis in Tribolium castaneum

Dusky (dy) is required for cytoskeletal reorganization during wing morphogenesis in Drosophila melanogaster, but which genes participate together with dy for wing morphogenesis has remained unclear. In Tribolium castaneum, dy is highly expressed at the late embryonic stage. Tissue-specific expression analysis indicated high expression levels of dy in the epidermis, head and fat body of late-stage larvae. RNA interference (RNAi) targeting dy significantly decreased adult wing size and caused improper folding of the elytra. Meanwhile, dy knockdown reduced the transcription of four-jointed (fj) and forked (f). Our results show that fj RNAi reduces adult wing size and that silencing f results in abnormal wing folding in T. castaneum. Interestingly, knocking down fj and f simultaneously phenocopies dy RNAi, suggesting that dy probably acts upstream of fj and f to regulate wing morphogenesis in T. castaneum.

LcMCII-1 is involved in the ROS-dependent senescence of the rudimentary leaves of Litchi chinensis

KEY MESSAGE

LcMCII - 1 is a type II metacaspase. Over-expression of LcMCII- 1 in Arabidopsis promoted ROS-dependent and natural senescence. Virus-induced LcMCII- 1 silencing delayed the ROS-dependent senescence of the rudimentary leaves of Litchi chinensis . Litchi is an evergreen woody fruit tree that is widely cultivated in subtropical and tropical regions. Its floral buds are mixed with axillary or apical panicle primordia, leaf primordia and rudimentary leaves. A low spring temperature is vital for litchi production as it promotes the abscission of the rudimentary leaves, which could otherwise prevent panicle development. Hence, climate change could present additional challenges for litchi production. We previously reported that reactive oxygen species (ROS) can substitute low-temperature treatment to induce the senescence of rudimentary leaves. We have now identified from RNA-Seq data a litchi type II metacaspase gene, LcMCII-1, that is responsive to ROS. Silencing LcMCII-1 by virus-induced gene silencing delayed ROS-dependent senescence. The ectopic over-expression of LcMCII-1 in transgenic Arabidopsis promoted ROS-dependent and natural senescence. Consistently, the transient expression of LcMCII-1 in tobacco leaf by agroinfiltration resulted in leaf yellowing. Our findings demonstrate that LcMCII-1 is positively involved in the regulation of rudimentary leaf senescence in litchi and provide a new target for the future molecular breeding of new cultivars that can set fruit in warmer climates.

Evidence for the transition from primary to peritectic phase growth during solidification of undercooled Ni-Zr alloy levitated by electromagnetic field

The Ni_83.25Zr_16.75 peritectic alloy was undercooled by electromagnetic levitation method up to 198 K. The measured dendritic growth velocity shows a steep acceleration at a critical undercooling of ΔT_crit = 124 K, which provides an evidence of the transition of the primary growth mode from Ni₇Zr₂ phase to peritectic phase Ni₅Zr. This is ascertained by combining the temperature-time profile and the evolution of the solidified microstructures. Below the critical undercooling, the solidified microstructure is composed of coarse Ni₇Zr₂ dendrites, peritectic phase Ni₅Zr and eutectic structure. However, beyond the critical undercooling, only a small amount of Ni₇Zr₂ phase appears in the solidified microstructure. The dendritic growth mechanism of Ni₇Zr₂ phase is mainly governed by solute diffusion. While, the dendritic growth mechanism of Ni₅Zr phase is mainly controlled by thermal diffusion and liquid-solid interface atomic attachment kinetics.

Note: Attenuation motion of acoustically levitated spherical rotor

Here we observe the attenuation motion of spherical rotors levitated by near-field acoustic radiation force and analyze the factors that affect the duration time of free rotation. It is found that the rotating speed of freely rotating rotor decreases exponentially with respect to time. The time constant of exponential attenuation motion depends mainly on the levitation height, the mass of rotor, and the depth of concave ultrasound emitter. Large levitation height, large mass of rotor, and small depth of concave emitter are beneficial to increase the time constant and hence extend the duration time of free rotation.

Responses of rose RhACS1 and RhACS2 promoters to abiotic stresses in transgenic Arabidopsis thaliana

Promoter activities of RhACS1 and RhACS2 , two rose genes involved in ethylene biosynthesis, are highly sensitive to various abiotic stresses in an organ-specific manner. Our previous studies indicated that two rose (Rosa hybrida) 1-aminocyclopropane-1-carboxylic acid synthase genes, RhACS1 and RhACS2, play a role in dehydration-induced ethylene production and inhibition of cell expansion in rose petals. Here, both RhACS1 and RhACS2 promoters were analyzed using histochemical staining and glucuronidase synthase (GUS) gene reporter activity assays following their introduction into transgenic Arabidopsis thaliana plants. It was found that the promoter activities of both genes were strong throughout the course of development from young seedlings to mature flowering plants in various organs, including hypocotyls, cotyledons, leaves, roots and lateral roots. RhACS1 promoter activity was induced by drought in both rosette leaves and roots of transgenic A. thaliana lines, but was reduced following a re-hydration treatment. In contrast, RhACS2 promoter activity was decreased by drought in rosette leaves, while its response pattern was similar to that of RhACS1 in roots. A mannitol treatment induced the activity of both the RhACS1 and RhACS2 promoters, indicating that both genes are also regulated by osmotic stress. In addition, RhACS2 appeared to be abscisic acid (ABA)-inducible, while RhACS1 was less sensitive to ABA. Finally, four truncated sequences of the RhACS1 promoter were generated and GUS activity assays demonstrated that deleting a 327 bp region between bp 862 and -535 resulted in a substantial decrease of the promoter activity. Taken together, our results suggest that the RhACS1 and RhACS2 promoters respond to abiotic stresses in a developmentally regulated and spatially specific manner.

The near-field acoustic levitation of high-mass rotors

Here we demonstrate that spherical rotors with 40 mm diameter and 0-1 kg mass can be suspended more than tens of micrometers away from an ultrasonically vibrating concave surface by near-field acoustic radiation force. Their rotating speeds exceed 3000 rpm. An acoustic model has been developed to evaluate the near-field acoustic radiation force and the resonant frequencies of levitation system. This technique has potential application in developing acoustic gyroscope.

RhHB1 mediates the antagonism of gibberellins to ABA and ethylene during rose (Rosa hybrida) petal senescence

Rose (Rosa hybrida) is one of the most important ornamental plants worldwide; however, senescence of its petals terminates the ornamental value of the flower, resulting in major economic loss. It is known that the hormones abscisic acid (ABA) and ethylene promote petal senescence, while gibberellins (GAs) delay the process. However, the molecular mechanisms underlying the antagonistic effects amongst plant hormones during petal senescence are still unclear. Here we isolated RhHB1, a homeodomain-leucine zipper I transcription factor gene, from rose flowers. Quantitative RT-PCR and GUS reporter analyses showed that RhHB1 was strongly expressed in senescing petals, and its expression was induced by ABA or ethylene in petals. ABA or ethylene treatment clearly accelerated rose petal senescence, while application of the gibberellin GA3 delayed the process. However, silencing of RhHB1 delayed the ABA- or ethylene-mediated senescence, and resulted in higher petal anthocyanin levels and lower expression of RhSAG12. Moreover, treatment with paclobutrazol, an inhibitor of GA biosynthesis, repressed these delays. In addition, silencing of RhHB1 blocked the ABA- or ethylene-induced reduction in expression of the GA20 oxidase encoded by RhGA20ox1, a gene in the GA biosynthetic pathway. Furthermore, RhHB1 directly binds to the RhGA20ox1 promoter, and silencing of RhGA20ox1 promoted petal senescence. Eight senescence-related genes showed substantial differences in expression in petals after treatment with GA3 or paclobutrazol. These results suggest that RhHB1 mediates the antagonistic effect of GAs on ABA and ethylene during rose petal senescence, and that the promotion of petal senescence by ABA or ethylene operates through an RhHB1-RhGA20ox1 regulatory checkpoint.

RhNAC3, a stress-associated NAC transcription factor, has a role in dehydration tolerance through regulating osmotic stress-related genes in rose petals

Petal cell expansion depends on cell wall metabolism, changes in cell turgor pressure and restructuring of the cytoskeleton, and recovery ability of petal cell expansion is defined as an indicator of dehydration tolerance in flowers. We previously reported that RhNAC2, a development-related NAC domain transcription factor, confers dehydration tolerance through regulating cell wall-related genes in rose petals. Here, we identify RhNAC3, a novel rose SNAC gene, and its expression in petals induced by dehydration, wounding, exogenous ethylene and abscisic acid (ABA). Expression studies in Arabidopsis protoplasts and yeast show that RhNAC3 has transactivation activity along its full length and in the carboxyl-terminal domain. Silencing RhNAC3 in rose petals by virus-induced gene silencing (VIGS) significantly decreased the cell expansion of rose petals under rehydration conditions. In total, 24 of 27 osmotic stress-related genes were down-regulated in RhNAC3-silenced rose petals, while only 4 of 22 cell expansion-related genes were down-regulated. Overexpression of RhNAC3 in Arabidopsis gave improved drought tolerance, with lower water loss of leaves in transgenic plants. Arabidopsis ATH1 microarray analysis showed that RhNAC3 regulated the expression of stress-responsive genes in overexpressing lines, and further analysis revealed that most of the RhNAC3-up-regulated genes were involved in the response to osmotic stress. Comparative analysis revealed that different transcription regulation existed between RhNAC3 and RhNAC2. Taken together, these data indicate that RhNAC3, as a positive regulator, confers dehydration tolerance of rose petals mainly through regulating osmotic adjustment-associated genes.

RhEXPA4, a rose expansin gene, modulates leaf growth and confers drought and salt tolerance to Arabidopsis

Drought and high salinity are major environmental conditions limiting plant growth and development. Expansin is a cell-wall-loosening protein known to disrupt hydrogen bonds between xyloglucan and cellulose microfibrils. The expression of expansin increases in plants under various abiotic stresses, and plays an important role in adaptation to these stresses. We aimed to investigate the role of the RhEXPA4, a rose expansin gene, in response to abiotic stresses through its overexpression analysis in Arabidopsis. In transgenic Arabidopsis harboring the Pro RhEXPA4 ::GUS construct, RhEXPA4 promoter activity was induced by abscisic acid (ABA), drought and salt, particularly in zones of active growth. Transgenic lines with higher RhEXPA4 level developed compact phenotypes with shorter stems, curly leaves and compact inflorescences, while the lines with relatively lower RhEXPA4 expression showed normal phenotypes, similar to the wild type (WT). The germination percentage of transgenic Arabidopsis seeds was higher than that of WT seeds under salt stress and ABA treatments. Transgenic plants showed enhanced tolerance to drought and salt stresses: they displayed higher survival rates after drought, and exhibited more lateral roots and higher content of leaf chlorophyll a under salt stress. Moreover, high-level RhEXPA4 overexpressors have multiple modifications in leaf blade epidermal structure, such as smaller, compact cells, fewer stomata and midvein vascular patterning in leaves, which provides them with more tolerance to abiotic stresses compared to mild overexpressors and the WT. Collectively, our results suggest that RhEXPA4, a cell-wall-loosening protein, confers tolerance to abiotic stresses through modifying cell expansion and plant development in Arabidopsis.

RhNAC2 and RhEXPA4 are involved in the regulation of dehydration tolerance during the expansion of rose petals

Dehydration inhibits petal expansion resulting in abnormal flower opening and results in quality loss during the marketing of cut flowers. We constructed a suppression subtractive hybridization library from rose (Rosa hybrida) flowers containing 3,513 unique expressed sequence tags and analyzed their expression profiles during cycles of dehydration. We found that 54 genes were up-regulated by the first dehydration, restored or even down-regulated by rehydration, and once again up-regulated by the second dehydration. Among them, we identified a putative NAC family transcription factor (RhNAC2). With transactivation activity of its carboxyl-terminal domain in yeast (Saccharomyces cerevisiae) cell and Arabidopsis (Arabidopsis thaliana) protoplast, RhNAC2 belongs to the NAC transcription factor clade related to plant development in Arabidopsis. A putative expansin gene named RhEXPA4 was also dramatically up-regulated by dehydration. Silencing RhNAC2 or RhEXPA4 in rose petals by virus-induced gene silencing significantly decreased the recovery of intact petals and petal discs during rehydration. Overexpression of RhNAC2 or RhEXPA4 in Arabidopsis conferred strong drought tolerance in the transgenic plants. RhEXPA4 expression was repressed in RhNAC2-silenced rose petals, and the amino-terminal binding domain of RhNAC2 bound to the RhEXPA4 promoter. Twenty cell wall-related genes, including seven expansin family members, were up-regulated in Arabidopsis plants overexpressing RhNAC2. These data indicate that RhNAC2 and RhEXPA4 are involved in the regulation of dehydration tolerance during the expansion of rose petals and that RhEXPA4 expression may be regulated by RhNAC2.

[Development of a system for robot aided teeth alignment of complete denture]

OBJECTIVE

To develop a robot aid aligning artificial teeth for complete denture.

METHODS

The CRS-450, a 6-direction-free robot was utilized to make the grasped object realize any position and pose, and to develop an adjustable tooth arrangement machine. The geometry parameters of the shape of agomphious jaw were obtained through 3-D laser scanning and measuring system. The math's model, which was set up according to senior prosthodontic experts' experiences on tooth arrangement, was used to control program of experts in arranging teeth, 3-D denture simulation, and robots in arranging teeth. The program used VC++ and RAPL robot languages. When the teeth arrangement plan was formed, the data were transmitted to a robot, who would fix the position and finish the fabrication of complete denture.

RESULTS

A complete system of robot-aided complete denture teeth arranging was set up and tried using this system to make an artificial dentition for a patient. There were still some errors in the articulation of the dentition, which needed adjustment and perfection.

CONCLUSIONS

We succeed in using robot to fabricate artificial dentition for the first time. Although the dentition is not perfect in articulation, the system's scientific significance is profound. The results have proved that the designing idea and technical routine are workable.

[Antibacterial activity of 20 kinds of Chinese medicinal materials for Helicobacter pylori in vitro]

OBJECTIVE

To study the antibacterial activity of 20 Chinese medicinal materials for helicobacter pylori in vitro and the culture of hylicobacter pylori.

METHODS

Doubled-diluted method and tomato juice culture medium were adopted.

RESULTS

The detecting ratio of tomato juice culture medium to hylicobacter pylori was equal to that of skirrow culture medium; Radix Scutellariae, Flos Lonicerae, Radix Isatidis, Indigo Naturalis, Fructus Chebulae, Semen Ginkgo, Cortex Phellodendri, Rhizoma Corydalis and Cortex Fraxini have obvious effect of antibacterium to hyliocobater pylori.

[The research and development for dental office information system]

OBJECTIVE

To study how to use the technology of information management, data-base and graphics to develop the dental clinic information system.

METHODS

Base on the expert's demonstration and investigation, we made up the operative cord of the dental clinic. The PowerBuilder and SQL Anywhere Tools V6.0 was used to develop the information system.

RESULTS

There are 7 different sub-functional models in our system, and they are about patients, workers, finance, capital, expandable, technician lab., and maintenance. The system has been used in 8 dental clinics, and about 1,100 cases history were managed. The result showed us that the system has a strong and perfect function for clinical service, and it is easy to be used.

CONCLUSION

The system could enhance the user's management level and benefit to patients and clinical service.

[A clinical investigation on cataract surgery with 2.8 mm incision]

OBJECTIVE

The results of phacoemulsification which was performed through a 2.8 mm clear cornea tunnel incision and foldable intraocular lens (IOL) implantation were analyzed.

METHODS

On 126 eyes with cataract of 105 cases, phacoemulsification with foldable IOL implantation was randomly performed. The results of postoperative vision, refraction, corneal edema, anterior chamber flare and the rate of corneal endothelial cell loss were retrospectively summarized.

RESULTS

The uncorrected visual acuities of postoperative 1 day, 3 days, 1 week, 2 - 3 months, >or= 0.5 were in 102 eyes (81.0%), 108 eyes (85.7%), 112 eyes (88.9%) and 112 eyes (88.9%), respectively. The mean diopters of astigmatism at postoperative 3 days, 1 week, 1 month and 3 months were (1.09 +/- 0.51) D, (1.02 +/- 0.47) D, (0.88 +/- 0.52) D and (0.81 +/- 0.62) D, respectively. The mean diopters of astigmatism at postoperative 1 week, 1 month and 3 months compared with that before the surgery had no significant difference (P > 0.05). The comparison between the preoperative astigmatism and that at postoperative 3 months showed that only about 0.08D of change existed. The postoperative corneal edema and anterior chamber flare were mild, the anterior chamber configuration remained well, and the rate of endothelial cell loss was 11.9%.

CONCLUSIONS

The surgical incision is small and easy to perform. Postoperatively, the reaction is mild, the change of astigmatism is small in degree, the best visual acuity can be obtained at the early stage and the refractive status is stable, thus the duration for restoration is greatly shortened.

[Apoptosis in the developing tooth of postnatal rat]

OBJECTIVE

To study apoptosis in the developing tooth of postnatal rat.

METHODS

Transferase-mediated, dUTP-biotin nick end labeling(TUNEL) method was utilized to label the paraffin sections of the lower and upper jaws taken from 3 days and 9 days of postnatal rats.

RESULTS

Positive stains for the presence of apoptosis were observed in ameloblasts, especially in cervical loop region, and stellate reticulum cells. Odontoblasts at the tip of developing molars in which physiological osteodentin was forming were strongly positive. A few dental pulp cells were labeled.

CONCLUSION

Apotosis is a biological process, which play an important role in the formation of teeth. Apoptosis may take place in epithelial derived cells as well as mesenchymal-derived cells.

[Three dimensional reconstruction of human permanent teeth]

OBJECTIVE

Dental anatomy is one of the most important basic courses in the education of stomatology. The deep understanding of morphologic characters is closely instructive to the clinic of endodontics, oral surgery, orthodontics and prosthodontics.

METHODS

In present study, 32 permanent teeth from a skull specimen were inputted into computer after the processes of burying, grinding, photographing, scanning and recognizing. By the techniques of reconstruction, the 3D stereo tooth models were retrieved from 2D digital data.

RESULTS

On the basis of those 3D data, computer graphics techniques were used to realize the lighted, smoothed and shaded teeth.

CONCLUSION

Such a series of data teeth might be applicated as a corner stone of the computer aided instruction (CAI) in stomatology.