Sb3+/Sm3+ Codoped Cs2NaScCl6 All-Inorganic Double Perovskite: Blue Emission of Self-Trapped Excitons and Red-Emission via Energy Transfer.

The lead-free halide perovskites possess nontoxicity and excellent chemical stability, whereas relatively weak luminescence intensity limits their potential in practical applications. Therefore, strengthening the luminescence intensity and expanding application fields are urgent tasks for the development of lead-free halide perovskites. In this paper, antimony-doped Cs2NaScCl6 crystals synthesized by a solvothermal method emit bright, deep blue photoluminescence at 447 nm. The photoluminescence (PL), photoluminescence excitation (PLE), and absorption spectra demonstrate that Sb3+ doping effectively activate the intrinsic "dark self-trapped exciton (STE)," leading to an impressive photoluminescence quantum yield (PLQY) value of 78.31% for 1% Sb3+ doping. Furthermore, the luminescence intensity remains above 92% compared with the fresh sample without secondary phases detected even after 90 days under environmental conditions. To expand the emission spectra, rare-earth Sm3+ is further incorporated into Cs2NaScCl6:1% Sb3+ crystals. The results show that Sb ions not only enhance intrinsic STE luminescence but also serve as sensitizers to boost the red-light emission of Sm3+, leading to a significant 500-fold increase in red emission intensity. Finally, the PLQY reaches a stunning 86.78%. These findings provide valuable insights in the design of Sb ion-doped lead-free double perovskites, broadening the application fields in various optoelectronic devices.

First Report of Agroathelia rolfsii Causing Southern Blight on Lippia (Phyla canescens) in Guangzhou, China.

Lippia (Phyla canescens) is a fast-growing, mat-forming, and prostrate perennial plant well adapted to infertile, high-saline, and drought environments (Leigh, et al. 2004). It arrived in China from Japan as a flowering ground cover in 2001 (Cai, et al. 2004). In June 2022, southern blight appeared in our nursery of the Floriculture Research Institute of Guangdong Academy of Agricultural Sciences. High temperature and damp environment are major factors for this disease. The symptoms of top-layer plants were not easily detected, but they were slightly yellowed. A yellowish-brown water-soak lesion appeared on the stems and lowest leaves exposed to soil. White mycelium appeared in the middle stage. Finally, the surface plants showed water-soak decay, and a mass of beige to black-brown rapeseed-shaped sclerotia appeared on the residue and surrounding soil; these plants died. Sclerotia and mycelia were collected from disease tissue, and after surface sterilization, sclerotia was cultured on potato dextrose agar (PDA) at 28±2°C in an incubator without light. Eight fungal isolates with similar colony morphologies were consistently isolated by purifying from different sampling areas. The isolates exhibited obvious septa and a clamp connection structure within the white mycelium. The average growth rate was 26.86±0.06 mm/day. Numerous white granular sclerotia were produced on the mycelium 6 days later. The sclerotia with a diameter of 1.24±0.07mm (n=189) gradually changed from diage to yellow to brown. A typical strain B1 was selected for further identification, targeting its 18S rRNA and LSU rRNA sequences (Yang, et al. 2011; Xue, et al. 2019). Its 18S rRNA sequence (GenBank Accession No. OR517233, 1626 bp) is 99.63% and 99.57% identical to Athelia rolfsii (AY665774, 1179bp; KC670714, 1775bp; JF819726, 1781bp). Its LSU rRNA sequence (OR539570, 757 bp) is 99.87% identical to Agroathelia rolfsii (OR526537, 904 bp). For Athelia rolfsii, a synonym of Agroathelia rolfsii, by combining the morphological characteristics and molecular identification, the isolate pathogen B1 was confirmed to be Agroathelia rolfsii (the teleomorph of Sclerotium rolfsii). To fullfill Koch's postulates, we inoculated the mycelial plugs to healthy lippia stems and leaves which has grown for one year, with PDA plugs free of mycelium as the control. All the plants were kept in a greenhouse at 28±2°C with a 14-h photoperiod and 80% relative humidity. Each treatment was repeated thrice and vaccinated with 6 points. At 7 d following inoculation, all plants inoculated with B1 showed typical symptoms, but the control group was asymptomatic, and sclerotia appeared 17d after inoculation. Using the same protocol mentioned above, pathogenic fungal was reisolated only from treated groups, but not from the control group. Chose three of the pathogens for 18S rRNA and LSU rRNA sequencing, the results showed 100% identity to B1, the same as its microstructure. There are few reports about the disease on P. canescens. Sosa (2007) investigated the pathogens on P. canescens in Argentina, 16 fungi were found but no A. rolfsii. Sclerotium rolfsii were identified on P. nodiflora or P. lanceolata (Michaux) Greene in America (Farr, et al. 1989). To our knowledge, this is the first report in China. Because this pathogen has wide-ranging hosts and causes serious damage, the results from this study will offer guidance for the prevention and treatment of this disease.

The Integrated mRNA and miRNA Approach Reveals Potential Regulators of Flowering Time in Arundina graminifolia.

Orchids are among the most precious flowers in the world. Regulation of flowering time is one of the most important targets to enhance their ornamental value. The beauty of Arundina graminifolia is its year-round flowering, although the molecular mechanism of this flowering ability remains masked. Therefore, we performed a comprehensive assessment to integrate transcriptome and miRNA sequencing to disentangle the genetic regulation of flowering in this valuable species. Clustering analyses provided a set of molecular regulators of floral transition and floral morphogenesis. We mined candidate floral homeotic genes, including FCA, FPA, GI, FT, FLC, AP2, SOC1, SVP, GI, TCP, and CO, which were targeted by a variety of miRNAs. MiR11091 targeted the highest number of genes, including candidate regulators of phase transition and hormonal control. The conserved miR156-miR172 pathway of floral time regulation was evident in our data, and we found important targets of these miRNAs in the transcriptome. Moreover, endogenous hormone levels were determined to decipher the hormonal control of floral buds in A. graminifolia. The qRT-PCR analysis of floral and hormonal integrators validated the transcriptome expression. Therefore, miRNA-mediated mining of candidate genes with hormonal regulation forms the basis for comprehending the complex regulatory network of perpetual flowering in precious orchids. The findings of this study can do a great deal to broaden the breeding programs for flowering time manipulation of orchids.

Genome-Wide Identification, Expression, and Molecular Characterization of the CONSTANS-like Gene Family in Seven Orchid Species.

The orchid is one of the most distinctive and highly valued flowering plants. Nevertheless, the CONSTANS-like (COL) gene family plays significant roles in the control of flowering, and its functions in Orchidaceae have been minimally explored. This research identified 68 potential COL genes within seven orchids' complete genome, divided into three groups (groups I, II, and III) via a phylogenetic tree. The modeled three-dimensional structure and the conserved domains exhibited a high degree of similarity among the orchid COL proteins. The selection pressure analysis showed that all orchid COLs suffered a strong purifying selection. Furthermore, the orchid COL genes exhibited functional and structural heterogeneity in terms of collinearity, gene structure, cis-acting elements within their promoters, and expression patterns. Moreover, we identified 50 genes in orchids with a homology to those involved in the COL transcriptional regulatory network in Arabidopsis. Additionally, the first overexpression of CsiCOL05 and CsiCOL09 in Cymbidium sinense protoplasts suggests that they may antagonize the regulation of flowering time and gynostemium development. Our study will undoubtedly provide new resources, ideas, and values for the modern breeding of orchids and other plants.

Genetic insights into the regulatory pathways for continuous flowering in a unique orchid Arundina graminifolia.

BACKGROUND: Manipulation of flowering time and frequency of blooming is key to enhancing the ornamental value of orchids. Arundina graminifolia is a unique orchid that flowers year round, although the molecular basis of this flowering pattern remains poorly understood. RESULTS: We compared the A. graminifolia transcriptome across tissue types and floral developmental stages to elucidate important genetic regulators of flowering and hormones. Clustering analyses identified modules specific to floral transition and floral morphogenesis, providing a set of candidate regulators for the floral initiation and timing. Among candidate floral homeotic genes, the expression of two FT genes was positively correlated with flower development. Assessment of the endogenous hormone levels and qRT-PCR analysis of 32 pathway-responsive genes supported a role for the regulatory networks in floral bud control in A. graminifolia. Moreover, WGCNA showed that flowering control can be delineated by modules of coexpressed genes; especially, MEgreen presented group of genes specific to flowering. CONCLUSIONS: Candidate gene selection coupled with hormonal regulators brings a robust source to understand the intricate molecular regulation of flowering in precious orchids.

The genome of Cymbidium sinense revealed the evolution of orchid traits.

The Orchidaceae is of economic and ecological importance and constitutes ˜10% of all seed plant species. Here, we report a genome physical map for Cymbidium sinense, a well-known species belonging to genus Cymbidium that has thousands of natural variation varieties of flower organs, flower and leaf colours and also referred as the King of Fragrance, which make it arose into a unique cultural symbol in China. The high-quality chromosome-scale genome assembly was 3.52 Gb in size, 29 638 protein-coding genes were predicted, and evidence for whole-genome duplication shared with other orchids was provided. Marked amplification of cytochrome- and photosystem-related genes was observed, which was consistent with the shade tolerance and dark green leaves of C. sinense. Extensive duplication of MADS-box genes, and the resulting subfunctional and expressional differentiation, was associated with regulation of species-specific flower traits, including wild-type and mutant-type floral patterning, seasonal flowering and ecological adaption. CsSEP4 was originally found to positively regulate gynostemium development. The CsSVP genes and their interaction proteins CsAP1 and CsSOC1 were significantly expanded and involved in the regulation of low-temperature-dependent flowering. Important genetic clues to the colourful leaf traits, purple-black flowers and volatile trait in C. sinense were also found. The results provide new insights into the molecular mechanisms of important phenotypic traits of Cymbidium and its evolution and serve as a powerful platform for future evolutionary studies and molecular breeding of orchids.

Stage Specificity, the Dynamic Regulators and the Unique Orchid Arundina graminifolia.

Orchids take years to reach flowering, but the unique bamboo orchid (Arundina graminifolia) achieves reproductive maturity in six months and then keeps on year round flowering. Therefore, studying different aspects of its growth, development and flowering is key to boost breeding programs for orchids. This study uses transcriptome tools to discuss genetic regulation in five stages of flower development and four tissue types. Stage specificity was focused to distinguish genes specifically expressed in different stages of flower development and tissue types. The top 10 highly expressed genes suggested unique regulatory patterns for each stage or tissue. The A. graminifolia sequences were blasted in Arabidopsis genome to validate stage specific genes and to predict important hormonal and cell regulators. Moreover, weighted gene co-expression network analysis (WGCNA) modules were ascertained to suggest highly influential hubs for early and late stages of flower development, leaf and root. Hormonal regulators were abundant in all data sets, such as auxin (LAX2, GH3.1 and SAUR41), cytokinin (LOG1), gibberellin (GASA3 and YAB4), abscisic acid (DPBF3) and sucrose (SWEET4 and SWEET13). Findings of this study, thus, give a fine sketch of genetic variability in Orchidaceae and broaden our understanding of orchid flower development and the involvement of multiple pathways.

Involvement of CsERF2 in leaf variegation of Cymbidium sinense 'Dharma'.

MAIN CONCLUSION: CsERF2, an ethylene response factor, plays a role in leaf variegation. Leaf variegation is a main ornamental characteristic in Cymbidium sinense (C. sinense). However, the mechanisms of leaf color variegation remain largely unclear. In the present study, we analyzed the cytological and physiological features, as well as molecular analyses of leaves from wild-type (WT) and leaf variegation mutants of Cymbidium sinense 'Dharma'. Chloroplasts with typical and functional structures were discovered in WT and green sectors of the mutants leaves (MG), but not in yellow sectors of the mutant leaves (MY). The activities of key enzymes involved in chlorophyll (Chl) degradation and their substrate contents were significantly increased in MY. Genes related to Chl degradation also showed a significant up-regulation in MY. Transcriptomic analysis showed that the expression of all identified ethylene response factors (ERFs) was significantly up-regulated, and the 1-aminocyclopropane-1-carboxylic acid (ACC) content in MY was significantly higher compared with MG. QRT-PCR analysis validated that the expression levels of genes related to Chl degradation could be positively affected by ethylene (ETH) treatment. Stable overexpression of CsERF2 in Nicotiana tabacum (N. tabacum) led to a decrease in Chl content and abnormal chloroplast. Transcriptomic analysis and qRT-PCR results showed that the KEGG pathway related to chloroplast development and function showed significant change in transgenic N. tabacum. Therefore, the leaf color formation of C. sinense was greatly affected by chloroplast development and Chl metabolism. CsERF2 played an important role in leaf variegation of C. sinense.

Identification and Characterization of NPR1 and PR1 Homologs in Cymbidium orchids in Response to Multiple Hormones, Salinity and Viral Stresses.

The plant nonexpressor of pathogenesis-related 1 (NPR1) and pathogenesis-associated 1 (PR1) genes play fundamental roles in plant immunity response, as well as abiotic-stress tolerance. Nevertheless, comprehensive identification and characterization of NPR1 and PR1 homologs has not been conducted to date in Cymbidium orchids, a valuable industrial crop cultivated as ornamental and medicinal plants worldwide. Herein, three NPR1-like (referred to as CsNPR1-1, CsNPR1-2, and CsNPR1-3) and two PR1-like (CsPR1-1 and CsPR1-2) genes were genome-widely identified from Cymbidium orchids. Sequence and phylogenetic analysis revealed that CsNPR1-1 and CsNPR1-2 were grouped closest to NPR1 homologs in Zea mays (sharing 81.98% identity) and Phalaenopsis (64.14%), while CsNPR1-3 was classified into a distinct group with Oryza sativa NPR 3 (57.72%). CsPR1-1 and CsPR1-2 were both grouped closest to Phalaenopsis PR1 and other monocot plants. Expression profiling showed that CsNPR1 and CsPR1 were highly expressed in stem/pseudobulb and/or flower. Salicylic acid (SA) and hydrogen peroxide (H2O2) significantly up-regulated expressions of CsNPR1-2, CsPR1-1 and CsPR1-2, while CsNPR1-3, CsPR1-1 and CsPR1-2 were significantly up-regulated by abscisic acid (ABA) or salinity (NaCl) stress. In vitro transcripts of entire Cymbidium mosaic virus (CymMV) genomic RNA were successfully transfected into Cymbidium protoplasts, and the CymMV infection up-regulated the expression of CsNPR1-2, CsPR1-1 and CsPR1-2. Additionally, these genes were transiently expressed in Cymbidium protoplasts for subcellular localization analysis, and the presence of SA led to the nuclear translocation of the CsNPR1-2 protein, and the transient expression of CsNPR1-2 greatly enhanced the expression of CsPR1-1 and CsPR1-2. Collectively, the CsNPR1-2-mediated signaling pathway is SA-dependent, and confers to the defense against CymMV infection in Cymbidium orchids.

Highly Efficient Protoplast Isolation and Transient Expression System for Functional Characterization of Flowering Related Genes in Cymbidium Orchids.

Protoplast systems have been proven powerful tools in modern plant biology. However, successful preparation of abundant viable protoplasts remains a challenge for Cymbidium orchids. Herein, we established an efficient protoplast isolation protocol from orchid petals through optimization of enzymatic conditions. It requires optimal D-mannitol concentration (0.5 M), enzyme concentration (1.2 % (w/v) cellulose and 0.6 % (w/v) macerozyme) and digestion time (6 h). With this protocol, the highest yield (3.50 × 107/g fresh weight of orchid tissue) and viability (94.21%) of protoplasts were obtained from flower petals of Cymbidium. In addition, we achieved high transfection efficiency (80%) through the optimization of factors affecting polyethylene glycol (PEG)-mediated protoplast transfection including incubation time, final PEG4000 concentration and plasmid DNA amount. This highly efficient protoplast-based transient expression system (PTES) was further used for protein subcellular localization, bimolecular fluorescence complementation (BiFC) assay and gene regulation studies of flowering related genes in Cymbidium orchids. Taken together, our protoplast isolation and transfection protocol is highly efficient, stable and time-saving. It can be used for gene function and molecular analyses in orchids and other economically important monocot crops.

Comparative Metabolomic Analysis Reveals Distinct Flavonoid Biosynthesis Regulation for Leaf Color Development of Cymbidium sinense 'Red Sun'.

The colorful leaf is an important ornamental character of Cymbidium sinense (C. sinense), especially the red leaf, which has always been attracted by breeders and consumers. However, little is documented on the formation mechanism of the red leaf of C. sinense. In this study, the changing patterns of flavonoid-related metabolites, corresponding enzyme activities and genes expression in the leaves of C. sinense 'Red Sun' from red to yellow and finally to green was investigated. A total of 196 flavonoid-related metabolites including 11 anthocyanins metabolites were identified using UPLC-MS/MS-based approach. In the process of leaf color change, 42 metabolites were identified as having significantly different contents and the content of 28 differential metabolites turned to zero. In anthocyanin biosynthetic pathway, content of all 15 identified metabolites showed downregulation trend in the process of leaf color change. Among the 15 metabolites, the contents of Naringenin chalcone, Pelargonidin O-acetylhexoside and Anthocyanin 3-O-beta-d-glucoside decreased to zero in the green leaf stage. The changing pattern of enzyme activity of 10 enzymes involved in the anthocyanin biosynthetic pathway showed different trends from red leaves that have turned yellow and finally green, while the expression of genes encoding these enzymes was all down-regulated in the process of leaf color change. The results of this study revealed the types of flavonoid-related metabolites and the comprehensive analysis of metabolites content, enzyme activities and genes expression providing a new reference for breeders to improve the leaf color of C. sinense 'Red Sun'.

Low-temperature-induced changes in the transcriptome reveal a major role of CgSVP genes in regulating flowering of Cymbidium goeringii.

BACKGROUND: Cymbidium goeringii is one of the most horticulturally important and popular ornamental plants in the orchid family (Orchidaceae). It blooms in winter during January-March and a period of low temperature is necessary for its normal flowering, otherwise there is flower bud abortion, which seriously affects the economic benefits. However, the molecular mechanism underlying winter-blooming behavior in C. goeringii is unclear. RESULTS: In this research, we firstly study the flowering physiology of C. goeringii by cytobiology observations and physiological experiments. Using comparative transcriptome analysis, we identified 582 differentially expressed unigenes responding to cold treatment that were involved in metabolic process, flowering time, hormone signaling, stress response, and cell cycle, implying their potential roles in regulating winter-blooming of C. goeringii. Twelve MADS-box genes among them were investigated by full-length cDNA sequence analysis and expression validation, which indicated that three genes within the SHORT VEGETATIVE PHASE (SVP) sub-group had the most significant repressed expression after cold treatment. Further analysis revealed that the SVP genes showed population variation in expression that correlated with cold-regulated flowering and responded to low temperature earlier than the flowering pathway integrators CgAP1, CgSOC1, and CgLFY, suggesting a potential role of CgSVP genes in the early stage of low-temperature-induced blooming of C. goeringii. Moreover, a yeast two-hybrid experiment confirmed that CgSVP proteins interacted with CgAP1 and CgSOC1, suggesting that they may synergistically control the process of C. goeringii flowering in winter. CONCLUSIONS: This study represents the first exploration of flowering physiology of C. goeringii and provides gene expression information that could facilitate our understanding of molecular regulation of orchid plant winter-flowering, which could provide new insights and practical guidance for improving their flowering regulation and molecular breeding.

Integrated mRNA and microRNA transcriptome variations in the multi-tepal mutant provide insights into the floral patterning of the orchid Cymbidium goeringii.

BACKGROUND: Cymbidium goeringii is a very famous traditional orchid plant in China, which is well known for its spectacular and diverse flower morphology. In particular, the multi-tepal mutants have considerable ecological and cultural value. However, the current understanding of the molecular mechanisms of floral patterning and multi-tepal development is limited. In this study, we performed expression profiling of both microRNA (miRNA) and mRNA from wild-type and typical multi-tepal-mutant flowers of C. goeringii for the first time, to identify the genes and pathways regulating floral morphogenesis in C. goeringii. RESULTS: Total clean reads of 98,988,774 and 100,188,534 bp were obtained from the wild-type and mutant library, respectively, and de novo assembled into 98,446 unigenes, with an average length of 989 bp. Among them, 18,489 were identified as differentially expressed genes between the two libraries according to comparative transcript profiling. The majority of the gene ontology terms and Kyoto Encyclopedia of Genes and Genomes pathway enrichment responses were for membrane-building and ploidy-related processes, consistent with the excessive floral organs and altered cell size observed in the mutant. There were 29 MADS-box genes, as well as a large number of floral-related regulators and hormone-responsive genes, considered as candidates regulating floral patterning of C. goeringii. Small RNA sequencing revealed 132 conserved miRNA families expressed in flowers of C. goeringii, and 11 miRNAs corresponding to 455 putative target genes were considered to be responsible for multi-tepal development. Importantly, integrated analysis of mRNA and miRNA sequencing data showed two transcription factor/microRNA-based genetic pathways contributing to the multi-tepal trait: well-known floral-related miR156/SPL and miR167/ARF regulatory modes involved in reproductive organ development; and the miR319/TCP4-miR396/GRF regulatory cascade probably regulating cell proliferation of the multi-tepal development. CONCLUSIONS: Integrated mRNA and miRNA profiling data provided comprehensive gene expression information on the wild-type and multi-tepal mutant at the transcriptional level that could facilitate our understanding of the molecular mechanisms of floral patterning of C. goeringii. These data could also be used as an important resource for investigating the genetics of floral morphogenesis and various biological mechanisms of orchid plants.

A novel membrane-bound E3 ubiquitin ligase enhances the thermal resistance in plants.

High temperature stress disturbs cellular homoeostasis and results in a severe retardation in crop growth and development. Thus, it is important to reveal the mechanism of plants coping with heat stress. In this study, a novel gene that we identified from Brassica napus, referred to as BnTR1, was found to play a key role in heat stress response in planta. BnTR1 is a membrane-bound RINGv (C4HC3) protein that displays E3 ligase activity in vitro. We demonstrated that modest expression of BnTR1 is sufficient to minimize adverse environmental influence and confers thermal resistance on development without any detrimental effects in B. napus and Oryza sativa. Our investigation into the action mechanism indicates that BnTR1 is likely to be involved in mediating Ca²âº dynamics by regulating the activity of calcium channels, which further alters the transcripts of heat shock factors and heat shock proteins contributing to plant thermotolerance. Hence, our study identified BnTR1 as a novel key factor underlying a conserved mechanism conferring thermal resistance in plants.

An auxin-responsive endogenous peptide regulates root development in Arabidopsis.

Auxin plays critical roles in root formation and development. The components involved in this process, however, are not well understood. Here, we newly identified a peptide encoding gene, auxin-responsive endogenous polypeptide 1 (AREP1), which is induced by auxin, and mediates root development in Arabidopsis. Expression of AREP1 was specific to the cotyledon and to root and shoot meristem tissues. Amounts of AREP1 transcripts and AREP1-green fluorescent protein fusion proteins were elevated in response to indoleacetic acid treatment. Suppression of AREP1 through RNAi silencing resulted in reduction of primary root length, increase of lateral root number, and expansion of adventitious roots, compared to the observations in wild-type plants in the presence of auxin. By contrast, transgenic plants overexpressing AREP1 showed enhanced growth of the primary root under auxin treatment. Additionally, root morphology, including lateral root number and adventitious roots, differed greatly between transgenic and wild-type plants. Further analysis indicated that the expression of auxin-responsive genes, such as IAA3, IAA7, IAA17, GH3.2, GH3.3, and SAUR-AC1, was significantly higher in AREP1 RNAi plants, and was slightly lower in AREP1 overexpressing plants than in wild-type plants. These results suggest that the novel endogenous peptide AREP1 plays an important role in the process of auxin-mediated root development.

Phosphorylation of 399S at CsHsp70 of Cymbidium sinense is essential to maintain chlorophyll stability.

The Chinese orchids symbolise nobility and gentility in China, and the variation of leaf color makes Cymbidium sinense more diversified and valuable. However, its color variations especially at the protein level still remain largely unexplored. In this study, the proteomics and phosphoproteomics of Cymbidium sinense leaf color variation mutants were studied. A total of 1059 differentially abundant proteins (DAPs) and 1127 differentially abundant phosphorylation sites belonging to 644 phosphoproteins (DAPPs) were identified in the yellow section of leaf variegation mutant of Cymbidium sinense (MY) compared with the green section (MG). Moreover, 349 co-expressing proteins were found in both omics' datasets, while only 26 proteins showed the same expression patterns in the two omics. The interaction network analysis of kinases and phosphatases showed that DAPs and DAPPs in photosynthesis, response to hormones, pigment metabolic process, phosphorylation, glucose metabolic process, and dephosphorylation might contribute to leaf color variation. The abundance of 28 Hsps and 28 phosphorylation sites belonging to 10 Hsps showed significant differences between MG and MY. CsHsp70 was selected to explore the function in Cymbidium sinense leaf variegation. The results showed CsHsp70 is essential for maintaining photosynthetic pigment content and the 399S phosphorylation site is crucial to the function of CsHsp70. Collectively, our findings construct a comprehensive coverage of protein and protein phosphorylation in leaf variegation of C. sinense, providing valuable insights into its formation mechanisms.

Integrated proteomic, transcriptomic, and metabolomic profiling reveals that the gibberellin-abscisic acid hub runs flower development in the Chinese orchid Cymbidium sinense.

The seasonal flowering Chinese Cymbidium produce an axillary floral meristem and require a dormancy period during cold conditions for flower development. However, the bud activation mechanism remains elusive. This study evaluates the multi-omics across six stages of flower development, along with functional analysis of core genes to decipher the innate mechanism of floral bud initiation and outgrowth in the Chinese orchid Cymbidium sinense. Transcriptome and proteome analyses identified 10 modules with essential roles in floral bud dormancy and activation. Gene clusters in the early stages of flower development were mainly related to flowering time regulation and meristem determination, while the late stages were correlated with hormone signaling pathways. The metabolome identified 69 potential hormones in which gibberellin (GA) and abscisic acid (ABA) were the main regulatory hubs, and GA4 and GA53 exhibited a reciprocal loop. Extraneous GA application caused rapid elongation of flower buds and promoted the expression of flower development genes. Contrarily, exogenous ABA application extended the dormancy process and ABA inhibitors induced dormancy release. Moreover, CsAPETALA1 (CsAP1) was identified as the potential target of ABA for floral bud activation. Transformation of CsAP1 in Arabidopsis and its transient overexpression in C. sinense protoplasts not only affected flowering time and floral organ morphogenesis in Arabidopsis but also orchestrated the expression of flowering and hormone regulatory genes. The presence of ABA response elements in the CsAP1 promoter, rapid downregulation of CsAP1 after exogenous ABA application, and the activation of the floral bud after ABA inhibitor treatment suggest that ABA can control bud outgrowth through CsAP1.

Genome-wide association analysis identified molecular markers and candidate genes for flower traits in Chinese orchid (Cymbidium sinense).

The orchid, the champagne of flowers, brings luxury, elegance, and novelty to nature. Cymbidium sinense is a symbol of gigantic floral variability on account of wavering shapes and sizes of floral organs, although marker-trait association (MTA) has not been studied for its floral traits. We evaluated markers associated with 14 floral traits of C. sinense through a genome-wide association study (GWAS) of 195 accessions. A total of 65 318 522 single-nucleotide polymorphisms (SNPs) and 3 906 176 insertion/deletion (InDel) events were identified through genotyping-by-sequencing. Among these, 4694 potential SNPs and 477 InDels were identified as MTAs at -log10 P > 5. The genes related to these SNPs and InDels were largely associated with floral regulators, hormonal pathways, cell division, and metabolism, playing essential roles in tailoring floral morphology. Moreover, 20 candidate SNPs/InDels linked to 11 genes were verified, 8 of which were situated on exons, one was located in the 5'-UTR and two were positioned in introns. Here, the multitepal trait-related gene RABBIT EARS (RBE) was found to be the most crucial gene. We analyzed the role of CsRBE in the regulation of flower-related genes via efficient transient overexpression in C. sinense protoplasts, and found that the floral homeotic genes CsAP3 and CsPI, as well as organ boundary regulators, including CsCUC and CsTCP genes, were regulated by CsRBE. Thus, we obtained key gene loci for important ornamental traits of orchids using genome-wide association analysis of populations with natural variation. The findings of this study can do a great deal to expedite orchid breeding programs for shape variability.

Functional conservation and divergence of SEPALLATA-like genes in floral development in Cymbidium sinense.

Cymbidium sinense is one of the most important traditional Chinese Orchids due to its unique and highly ornamental floral organs. Although the ABCDE model for flower development is well-established in model plant species, the precise roles of these genes in C. sinense are not yet fully understood. In this study, four SEPALLATA-like genes were isolated and identified from C. sinense. CsSEP1 and CsSEP3 were grouped into the AGL9 clade, while CsSEP2 and CsSEP4 were included in the AGL2/3/4 clade. The expression pattern of CsSEP genes showed that they were significantly accumulated in reproductive tissues and expressed during flower bud development but only mildly detected or even undetected in vegetative organs. Subcellular localization revealed that CsSEP1 and CsSEP4 were localized to the nucleus, while CsSEP2 and CsSEP3 were located at the nuclear membrane. Promoter sequence analysis predicted that CsSEP genes contained a number of hormone response elements (HREs) and MADS-box binding sites. The early flowering phenotype observed in transgenic Arabidopsis plants expressing four CsSEP genes, along with the expression profiles of endogenous genes, such as SOC1, LFY, AG, FT, SEP3 and TCPs, in both transgenic Arabidopsis and C. sinense protoplasts, suggested that the CsSEP genes played a regulatory role in the flowering transition by influencing downstream genes related to flowering. However, only transgenic plants overexpressing CsSEP3 and CsSEP4 caused abnormal phenotypes of floral organs, while CsSEP1 and CsSEP2 had no effect on floral organs. Protein-protein interaction assays indicated that CsSEPs formed a protein complex with B-class CsAP3-2 and CsSOC1 proteins, affecting downstream genes to regulate floral organs and flowering time. Our findings highlighted both the functional conservation and divergence of SEPALLATA-like genes in C. sinense floral development. These results provided a valuable foundation for future studies of the molecular network underlying floral development in C. sinense.

The Transcriptome Profiling of Flavonoids and Bibenzyls Reveals Medicinal Importance of Rare Orchid Arundina graminifolia.

Orchids are very important flowering plants that spend long juvenile phases before flowering. Along with aesthetic importance, they are rich sources of medicinal components. However, their long reproductive cycle is the major hurdle to study the medicinal efficacy. Arundina graminifolia is a rare orchid that grows fast, unlike other orchids, and this characteristic makes it an ideal plant to study the medicinal enrichment of orchids. Therefore, this study presents the identification of important medicinal components in various parts of A. graminifolia. Transcriptome analysis was performed for five stages (FD1-FD5) of flower development and four tissue types (mature flower, silique, root, and leaf) to ascertain genetic regulators of flavonoids and bibenzyls. Most of the genes showed the highest expression in roots as compared with other tissues. Weighted gene coexpression network analysis (WGCNA) was performed to identify the coexpression modules and the candidate genes involving biosynthesis pathways of these chemicals. MEyellow module contained the highly coexpressed genes. Moreover, the concentrations of phenylpropanoid, bibenzyls, and flavone were ascertained through high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Phenylpropanoid and bibenzyl were comparatively high in the leaf, while flavone showed a high concentration in the stem. The selected candidate genes [bibenzyl biosynthesis (BIBSY212), CYP84A1, CYP73A4, 4CLL7, UGT88B1, UGT73C3, anthocyanin synthase (ANS), phenylalanine ammonia-lyase (PAL), flavanone synthase FLS, and CHS8] were validated through quantitative real-time PCR (qRT-PCR). Most of these genes showed high expression in leaf and root as compared with other tissue. Therefore, the presence of bibenzyls and flavonoids in different parts of A. graminifolia and their molecular regulators can provide a quick source to decipher the medicinal efficacy of orchids.