Coordination and Supramolecular Assemblies from Alkali+-Cucurbit[5]uril-[CdCl_(4)]^(2-)Systems

Thispaper has investigated the coordination and supramolecular assemblies of alkali metal ions,cucurbit[5]uril(Q[5]),and[CdCl_(4)]^(2-)to confirm whether[CdCl_(4)]^(2-)can produce the“honeycomb effect”,induce coordination of alkali metal ions to Q[5],and form linear coordination polymers.In this work,the effect of alkali metal ions on the construction of Q[5]-Cd^(2+)ion system under acidic conditions was investigated.Five complexes were successfully obtained by solvent evaporation method.Among the five crystal structures obtained,it can be observed that the presence of[CdCl_(4)]^(2-)did not result in the complexation of alkali metal ions by the Q[5]molecule.Instead,a bowl-like Cd^(2+)@Q[5]complex was formed.Indeed,[CdCl_(4)]^(2-)did not produce the honeycomb effect but led to the formation of Q[5]-based honeycomb frameworks with hexagonal cellsoccupied by[CdCl_(4)]^(2-).The experimental results show that cadmium ion showed stronger ability to coordinate to Q[5]in HCl solution.

Inhibition Effects of Different Trace and Secondary Elements on Scab of Cucurbits(Cladosporium cucumerinum) and Their Effects on Enzyme Activities of Cucumber Plants

The paper was to explore the effect of trace and secondary elements on scab of cucurbits （ Cladosporium cucumerinum） and their effects on enzyme activities of cucumber plants. [ Method ] Indoor antifungd experiment and pot test was carried out to study the control effect of different trace and secondary dements on scab of cucu.rbits; after trace and secondary element compounds were sprayed for 7 d, the content of soluble protein and malondialdehyde （MDA） and the activities of peroxidase （POD） and superoxide dismutase （SOD） of cucumber leaves during seedling stage were simultaneously detected. [ Result] The inhibi- tion effects on scab of cucurbits were found in the three trace and secondary dements, especially for the CaC12 （66.9%）, and about 54.6% and 24.1% for ZnSO4 and H3 BO3 , respectively. When cucumber plants were infected by scab of cuea.rbits, the contents of MDA for all treatments were significantly decreased in cucum- ber leaves after spraying the three trace and secondary elements compared with control. The contents of soluble protein in cucumber seedling were increased by Zn- SO4 and H3 BO3 application, while the contents of POD and SOD were increased on ZnSO4 and CaCI2 treatments. The defense system of cucumber was induced and strengthened by application of the three trace and secondary elements. [ Conclusion ] The results provided the theoretical basis for practical application and research on resistance mechanism of using trace and secondary dements to control scab of eueurbits.

Phenylalanine ammonia-lyase gene families in cucurbit species: Structure, evolution, and expression

Phenylalanine ammonia-lyase （PAL）, the first enzyme of phenylpropanoid pathway, is always encoded by multigene families in plants. In this study, using genome-wide searches, 13 PAL genes in cucumber （CsPAL1-13） and 13 PALs in melon （Cm- PALl-13） were identified. In the corresponding genomes, ten of these PAL genes were located in tandem in two clusters, while the others were widely dispersed in different chromosomes as a single copy. The protein sequences of CsPALs and CmPALs shared an overall high identity to each other. In our previous report, 12 PAL genes were identified in watermelon （CIPAL1-12）. Thereby, a total of 38 cucurbit PAL members were included. Here, a comprehensive comparison of PAL gene families was performed among three cucurbit plants. The phylogenetic and syntenic analyses placed the cucurbit PALs as 11 CsPAL-CmPAL-CIPAL triples, of which ten triples were clustered into the dicot group, and the remaining one, CsPAL1-CmPAL8-CIPAL2, was grouped with gymnosperm PALs and might serve as an ancestor of cucurbit PALs. By comparing the syntenic relationships and gene structure of these PAL genes, the expansion of cucurbit PAL families might arise from a series of segmental and tandem duplications and intron insertion events. Furthermore, the expression profiling in different tissues suggested that different cucurbit PALs displayed divergent but overlapping expression profiles, and the CsPAL-CmPAL-CIPAL orthologs showed correlative expression patterns among three cucurbit plants. Taken together, this study provided an extensive description on the evolution and expression of cucurbit PAL gene families and might facilitate the further studies for elucidating the functions of PALs in cucurbit plants.

Small RNA deep sequencing reveals the presence of multiple viral infections in cucurbit crops in Guangdong,China

Viral diseases are among the most critical damaging factors that impose a global threat to the cucurbit industry.China is the world’s leading country for the production and consumption of cucurbits.Guangdong,a province in southern China dominated by the tropical and subtropical climate,favors the survival of different plant viruses and their vectors.Five main cucurbit crops showing various disease symptoms were surveyed and collected to identify viruses infecting cucurbits in Guangdong during 2018–2020.In the field,the incidence ranged from 5-30%,or even 60-100% in the case of severely infected cucurbits.A total of 357 symptomatic samples were collected and subsequently screened for cucurbit viruses by small RNA deep sequencing and assembly(sRSA).Seventeen virus species belonging to 10 genera were identified in the five main cucurbit crops.The most common viruses were papaya ringspot virus(PRSV;Potyvirus),zucchini tigre mosaic virus(ZTMV;Potyvirus),zucchini yellow mosaic virus(ZYMV;Potyvirus),and watermelon silver mottle virus(WSMoV;Orthotospovirus),with infection rates of 24.4,19.0,17.1,and 14.3%,respectively.Notably,the most prevalent viruses were melon yellow spot orthotospovirus(MYSV)in cucumber,PRSV in squash,cucumber green mottle mosaic virus(CGMMV;Tobamovirus)in bottle gourd,WSMoV in white gourd,and ZYMV in luffa.Mixed infections were prevalent,and the types of mixed infections varied substantially in different cucurbit crops.Moreover,the full-length nucleotide sequences of watermelon green mottle mosaic virus(WGMMV),CGMMV,and watermelon virus A(WVA;Wamavirus)identified in bottle gourd were cloned and analyzed.This study is the first reporting WGMMV infecting bottle gourd in China mainland.In summary,the results demonstrate that in Guangdong,the most prevalent viruses belong to potyviruses,orthotospoviruses,and tobamoviruses groups.The findings will facilitate agricultural researchers and farmers to plan and implement effective disease control strategies aiming at timely detection and management of cucurbit-infecting viral pathogens.

Study on the inclusion interactions of berberine hydrochloride and cucurbit[7] by spectrofluorimetry

The inclusion interaction between berberine hydrochloride （BRH） and cucurbit[7] （CB[7]） has been studied by spectrofluorimetry. The result showed that CB[7] interaction with BRH to form a stable inclusion complex with an association constant of 9.57 × 10^4 L/mol and the fluorescence intensity of the complex was enhanced in 17 times higher than that of the studied drug itself. Based on the significant enhancement of fluorescence intensity of BRH in inclusion complex, a spetrofluorimetric method with high sensitivity and selectivity was developed for the determination of BRH in aqueous solution. The linear range of the method was 3.2- 2 × 10^3 ng/mL with a detection limit of 1.1 ng/mL. The proposed procedure could be applied successfully to determination of BRH remained in pharmaceutical dosage forms, spiked human plasma and urine with satisfactory results.

Cucurbit Host Range of <i>Myrothecium roridum</i>Isolated from Watermelon

In 2010, a foliar and stem-lesion disease that produced moderate to severe defoliation of watermelon was observed in the southern Great Plains. The disease was ultimately determined to be caused by Myrothecium roridum. The objective of this study was to compare the susceptibility of the vegetation and fruit of a broad range of commercially important cucurbits to three isolates obtained from these foliar lesions on watermelon. In greenhouse foliar inoculation experiments, cantaloupe, honeydew, cucumber, squash, and watermelon were susceptible to the fungus with cantaloupe and honeydew being the most susceptible and watermelon the most resistant. Furthermore, greenhouse inoculations supported earlier field observations as differential resistance was exhibited among the watermelon cultivars as well as the cucurbit types. All tested cucurbit fruit exhibited interior lesions when inoculated sub-epidermally with M. roridum isolates. However, natural infection of watermelon and pumpkin fruit has never been reported.

Synthesis and Crystal Structure of a Binuclear Gadolinium（Ⅲ） Complex Bridged by Cucurbit[6]uril

A new cucurbit[6]uril bridsed binuclear complex {[Gd（H2O）6]2[Q6（H2O）]}C16·4H2O, where Q6 represents cucurbit[6]uril, has been synthesized and characterized by X-ray diffraction. The crystal structure shows that the complex has an extended cucurbit[6]uril-bridged structure consisting of two gadolinium（Ⅲ） ions, in which each gadolinium（Ⅲ） ion is coordinated with two neighboring carbonylic oxygen atoms of Q6 and six oxygen atoms of water molecules that leans toward one side of the portal. One disordered guest water molecule resides in the Q6 molecule cavity and occupies two different positions. Hydrogen bonds assemble the complcx to threedimensional supramolecular structure.

Chloroplast gene matK holds the barcodes for identification of Momordica(Cucurbitaceae) species from Indian subcontinent

DNA barcoding is a supplementary tool in plant systematics,extensively used to resolve the species level controversies.This paper details the identification of DNA barcodes for seven species of Momordica,using the chloroplast gene mat K.Since the species M.cymbalaria has been confused as a member of the genus Luffa,26 accessions of Momordica belonging to seven Indian species and two accessions of Luffa acutangula were included in this study.Analysis of mat K sequences has yielded distinct barcodes in M.charantia var.charantia,M.subangulata subsp.renigera,M.cochinchinensis,M.balsamina,M.cymbalaria and also in Luffa acutangula.Evolutionary status of each species was reflected as nucleotide polymorphisms in each sequence.The wild species M.dioica and M.sahyadrica have yielded one barcode but failed to get differentiated.Further,this study provides conclusive proof that M.cymbalaria is a member of Momordica genus.The phylogram generated was successful to distinguish the monoecious species of this genus,M.charantia,M.balsamina and M.cymbalaria,from the dioecious species M.dioica,M.sahyadrica,M.subangulata subsp.renigera and M.cochinchinensis.Thus,mat K locus,by accumulating the evolutionary sequence variations,is proven efficient to differentiate the Momordica species and to reveal their relatedness.

Characterization and Visible Light Photocatalytic Activity of Cucurbit[n]urils/CdS-MoS_(2)

In order to reduce the impact of CdS photogenerated electron-hole recombination on its photocatalytic performance,a narrow band gap semiconductor MoS_(2) and organic macromolecular cucurbit[n]urils(Q[n])were used to modify CdS.Q[n]/CdS-MoS_(2)(n=6,7,8)composite photocatalysts were synthesized by hydrothermal method.Infrared spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,field emission scanning electron microscopy,ultraviolet-visible and photoluminescence spectrum were used to characterize the structure,morphology and optical properties of the products,and the catalytic degradation of the solutions of methylene blue,rhodamine B and crystal violet by Q[n]/CdS-MoS_(2) composite catalyst was investigated.The results showed that the Q[n]played a regulatory role on the growth and crystallization of CdS-MoS_(2) particles,Q[n]/CdS-MoS_(2)(n=6,7,8)formed flower clusters with petal-like leaves,the flower clusters of petal-like leaves increased the surface area and active sites of the catalyst,the Q[n]/CdS-MoS_(2) barrier width decreased,the electron-hole pair separation efficiency was improved in the Q[6]/Cds-MoS_(2).Q[n]makes the electron-hole pair to obtain better separation and migration.The Q[6]/CdS-MoS_(2) and Q[7]/CdS-MoS2 have good photocatalytic activity for methylene blue,and the catalytic process is based on hydroxyl radical principle.

The Cytological Studies on Neglected and Underutilized Cucurbit Species with Special Reference to Chayote,an Under-Exploited Species

Cucurbitaceae family contains important economic and medical crops, they can be divided into two categories according to the worldwide consumption, use, and production. The Cucurbit Popular Crops (CuPoC) are comprised of cucumber, the Cucurbita group (pumpkin and squash), melon and watermelon. On the other hand, Neglected and Underutilized Cucurbit Species (NUCuS) group has been used as food sources, medicinal properties and elements in the elaboration of different types of items. The NUCuS is represented in this review work by bitter gourd, bottle gourd, chayote, ridge gourd, and snake gourd, which are recognized mainly in Asia. The center of origin of the majority of NUCuS was proposed to be in the Old World. In contrast, the origin of chayote or Sechiumedule (Jacq.) Sw. was suggested in the New World, precisely in Mesoamerican region based on linguistic uses and distribution of wild relatives. The environmental factors along with artificial selection, production systems and traditional knowledge have been influenced the evolutionary history of NUCuS, Infraspecific variation of chayote has been reported in Mexico over-described varietal groups. These descriptors were determined based on biochemical and morpho-structural traits;however, cytogenetic analyses are scarce. Specifically, chromosome and nuclear content analyses are important to support botanical groups, analyze artificial selection history, developing breeding and conservation programs. The present review paper discusses agronomic and evolutionary importance based on cytological evidence in NUCuS, mainly in the prominent chayote;with the perspective to prompt breeding, conservation, cytology, structural and functional genomics research for its sustainable utilization.

复合材料Cucurbit[6]uril/CdS-MoS_(2)吸附性能的研究

以硫代乙酰胺,氯化镉,钼酸钠和有机大分子六元瓜环(cucunbit[6]uril,Q[6])为原料,采用水热法在200℃反应24小时合成CdS-MoS_(2)和Q[6]/CdS-MoS_(2)。利用FT-IR、XRD、XPS、SEM和UV-Vis等手段对产物结构、形貌和光学等性质进行表征,并考察CdS-MoS_(2)和Q[6]/CdS-MoS_(2)复合吸附剂对次甲基蓝的吸附作用。结果表明,CdS-MoS_(2)和Q[6]/CdS-MoS_(2)形成了花团状形貌,使其表面积较大,吸附面积增加,对次甲基蓝表现出较高的吸附量和脱色率,吸附符合准二级动力学模型。

Cucurbit[n]uril-based nanostructure construction and modification

New fabrication method of nanostructures is of great importance for the applications of nanoscience and nanotechnology.This review summarizes cucurbit[n]uril(CB[n])-based nanostructure fabrication and modification approaches.These strategies include the use of CB[n]s as building blocks and supramolecular crosslinkers to fabricate nanostructures,to surface modify nanostructures,and as gatekeepers to control the release of encapsulated cargo.These nanostructures are used for drug delivery,bioimaging,chemical sensing,catalysis and other applications.CB[n]s often play a vital role in the fabrication of these nanos-tructures,and the realization of the applications.

Controllable fabrication of a supramolecular polymer incorporating twisted cucurbit[14]uril and cucurbit[8]uril via self-sorting

A linear supramolecular polymer with controllable features based on twisted cucurbit[14]uril(tQ[14])and cucurbit[8]uril(Q[8])was firstly fabricated via an effective self-sorting strategy.Herein we designed a monomer,1–butyl–1?-(naphthalen-2-ylmethyl)-4,4?-bipyridinium bromide(BNB),that contains bipyridyl,aliphatic butyl and aromatic naphthyl groups,simultaneously.Two host molecules,tQ[14]and Q[8]were employed to develop an effective strategy for constructing a linear supramolecular polymer with con-trollable features.The alkyl groups on both sides of BNB could insert into the two cavities of tQ[14],the naphthyl part of BNB viaπ-πstacking in Q[8]cavity,serving as the driving force for supramolecular polymerization.Through self-sorting of the monomer,tQ[14]and Q[8],led to the formation of the linear supramolecular polymer.Depolymerization could be achieved by addition of adamantane hydrochloride(AH)which driven two BNB guest molecules out of the Q[8]cavity.This self-sorting strategy has great potential,not only for designing supramolecular polymer materials with different controllable structures through introduction of multiple functional groups,but also for broadening the application of twisted cucurbit[14]uril in supramolecular chemistry.

瓜类褪绿黄化病毒(Cucurbit chlorotic yellows virus)在湖南省的首次报道及其流行动态研究

瓜类褪绿黄化病毒Cucurbit chlorotic yellows virus（CCYV）属长线形病毒科（closteroviridae）毛形病毒属（crinivirus）,在世界范围内给蔬菜生产造成了严重危害,病毒侵染造成果实重量减轻10%-33%,产量减少10%-12%。CCYV不能靠摩擦接毒,只能由烟粉虱以半持久方式传播,

Preparation and characterization of inclusion complexes of antitumor camptothecin with cucurbit[n=7,8]urils

The slightly water-soluble anticancer drug camptothecin(CPT) and its inclusion complexes with cucurbit[n = 7,8]uril(Q[n](n = 7,8)) were investigated.The formation of 1:2 complexes with Q[n](n = 7,8) in aqueous solution was confirmed by fluorescence spectroscopy and the apparent stability constants were determined to be higher than 3.01 × 1012 L2/mol2.The solid inclusion complexes of CPT and Q[n](n = 7,8) were also prepared by the co-evaporation method and characterized by Fourier transformation-infrared spectroscopy,differential scanning calorimetry and powder X-ray diffraction.Aqueous solubility and dissolution studies indicate that the complexes exhibited significantly increased dissolution rates compared with the pure drug and physical mixtures.The potential of Q[7] or Q[8] for stabilizing lactone modality of CPT was investigated by the High Performance Liquid Chromatography(HPLC) method.The results reveal more than 63% CPT lactone form(active form) in CPT-Q[7] or Q[8] complexes compared to only 36% CPT lactone form in the absence of Q[7] or Q[8] after being incubated in the phosphate buffer solution(pH 7.4 at 37 °C) for 5h.

Determination of L-phenylalanine by cucurbit[7]uril sensitized fluorescence quenching method

The determination method of L-phenylalartine （LPA） by fluorescence quenching was developed. The assay was based on the combination of the cucurbit[7]uril （CB [7]） with palmatine hydrochloride （PAL） reaction. In the presence of CB [7], the fluorescence of PAL was quenched by LPA which can be employed to detect LPA. Under the optimal conditions, a linear range 3.63 ×10^-8- 9.68 ×10^-6 mol/L and a detection limit 1.27 ×10^-8 mol/L of LPA were obtained. The relative standard deviation （R.S.D） was 1.8% obtained from a series of 11 standards each containing 6.05 ×10^-6 mol/L of LPA. This paper also discusses the mechanism of fluorescence indicator probe.

Replacing PVP by macrocycle cucurbit[6]uril to cap sub-5 nm Pd nanocubes as highly active and durable catalyst for ethanol electrooxidation

Pd nano cubes(NCs)en closed by six{100}facets are fasci nating model materials for both fun dame ntal studies and practical applicati ons.However,the only available method to prepare well-defined sub-10 nm Pd NCs was developed by Xia et al.more than 10 years ago,un avoidably using polyvinyl pyrrol id one(PVP)polymer to preve nt particle aggregati on.The strongly adsorbed PVP extremely deteriorates the catalysts*efficiency because of the high coverage of accessible surface-active sites.Numerous efforts have been devoted to replacing PVP with weaker capping agents but with limited progress predominately due to the difficulties in tuning the growth kinetics of Pd NCs.For the first time,we report that macrocycle cucurbit[6]uril(CB[6])can replace PVP in the synthesis of Pd NCs by dedicatedly controlling the growth parameters.CB[6]capped Pd NCs showed 1.1-1.5 times in creased specific surface area compared to the surfactant-free commercial Pd catalysts.Moreover,X-ray photoelectron spectroscopy dem on strated the modified electronic structure of Pd NCs through the carb onyl group of CB[6].Consequently,compared to the commercial catalysts,the obtained Pd NCs exhibited 7 times higher current density towards ethanol oxidation reaction.Remarkably,after 17 h of continuous work,it reduced deactivation by up to 1-4 orders of magnitude.

Effects of Inclusion of Chrysin in Cucurbit[8]uril on Its Stability, Solubility and Antioxidant Potential

The host-guest interaction between cucurbit[8]uril（Q[8]） and chrysin（CHR） has been studied by means of 1H NMR, mass spectrometry（MS）, differential thermal analysis（DTA）, and UV-Vis spectrophotometry. The results show that CHR forms a 1：1 inclusion complex with Q[8], with a binding constant of CHR with Q[8] by UV absorp- tion being 5.4 × 106. Phase solubility experiments show a 5.13-fold increase in the solubility of CHR through interac- tion with Q[8] {c（Q[8]）=10-4 real/L}. A study of the evolution of UV absorption spectra with time shows that Q[8] significantly increases the stability of CHR. The antioxidant activity of CHR-Q[8] has been tested by the ABTS me- thod. The CHR-Q[8] inclusion complex shows a better scavenging effect towards the ABTS radical than CHR, with respective IC50 values of 1.05 ×10-6 and 3.07× 10-6 mol/L. In vitro release studies have shown that CHR-Q[8] has a sustained release effcct.

Design and optimization on rootstock cutting mechanism of grafting robot for cucurbit

Cutting mechanisms in existing grafting machines are unable to completely cut through the rootstock growth point and can easily damage seedlings.During the mechanical operation of splice grafting,the cutting angle of the rootstock is an essential factor for ensuring the quality and survival rate of grafting seedlings and a stable process for grafting robots.Therefore,in this study,commonly used grafting rootstocks,e.g.,cucurbita moschata,and calabash gourd were used as research objects for studying and analyzing the cutting angle of a splice grafting method.The morphological and structural parameters of the rootstock and scion were measured,and a structural model of the internal cavity of the rootstock was constructed using an image analysis method.The critical cutting angles for the cucurbita moschata and calabash gourd seedlings were obtained.According to the analysis,the grafting cutting angles for cucumber seedlings matching with cucurbita moschata seedlings were 20°and 25°,respectively,and the fitting rate of the cutting surface of the rootstock and scion was 99.04%.A cutting mechanism for the rootstock growth point and geometric model of the cutting operation were established,and the structural parameters of the mechanism and cutting angle adjustment were optimized.A cutting performance test showed that the success rate of the pressing the cotyledons of cucurbita moschata seedlings was 96.67%,and the success rate of cutting was 98%.The cutting accuracy was 96.8%,and the cutting surface fitting rate of the rootstock and scion was 98.61%.The latter differed by 0.43%from the theoretical rate but met the requirements for the splice grafting method.Thus,this study can provide a reference for the design of a cutting mechanism for a grafting robot.

Cucurbit[10]uril-based chemistry

Cucurbit[n]urils （CB[n]s, n = 5-8,10,13-15） have been proven to be an interesting macrocyclic family with their distinctive molecular recognition properties and fascinating applications in fields such as catalysis, supramolecular materials, drug delivery and biological systems. With the biggest cavity in the CB[n]s family. CB[ 10] shows its unique molecular recognition properties that are rather distinctive from other CB [n]is. In this review, we summarize the progresses in CB[10]-based chemistry since CB[10] was first reported as CB[10]-CB[5] complex in 2001. Purification, molecular recognition and supramolecular assembly of CB[ 10] will be described and an outlook will be given for further exploration of CB[10]-based chemistry.