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.

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.

Determination of Pesticide Residue Cartap Using a Sensitive Fluorescent Probe

The insecticide cartap （CP） is non-fluorescent in aqueous solutions. This property makes its determination through direct fluorescent method difficult. In acidic medium and at room temperature, palmatine （PAL） can react with cucurbit[7]uril （CB[7]） to form stable complexes, and the fluorescence intensity of the complex is greatly enhanced. Significant quenching of the fluorescence intensity of the CB[7]-PAL complex was observed with the addition of cartap. Based on the significant quenching of the supramolecular complex fluorescence intensity, a new spectrofluorimetric method with high sensitivity and selectivity was developed to determine cartap in aqueous solution. The fluorescence quenching values （AF） showed good linear relationship with cartap concentrations from 0.009 to 2.4 ~tg mL-~ with a detection limit 0.0029 ~tg mE-x. The proposed method had been successfully applied to the determination of cartap residues in grain and vegetable with recoveries of 87.4-103%. In addition, the association constants of the complexes formed between the host and the guest were determined. The competing reaction and the supramolecular interaction mechanisms between the cartap and PAL as they fight for occupancy of the CB[7] cavity were studied using spectrofluorimetry, xH NMR and molecular modeling calculations.

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.

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.

Synthesis and Properties of pH and Temperature Responsive Copolymer with Pesudorotaxane Structure

pH and temperature responsive copolymers PNAM4VBCB of N-isopropyl acrylamide（NAM） and complex pseudorotaxane monomer N 1-（4-vinylbenzyl）-1,4-diaminobutane dihydrochloride with cucurbit[6]uril（CB[6]） threaded（4VBCB） were prepared via free-radical polymerization in aqueous solution.The copolymers were characterized by 1 H NMR,Fourier transform infrared（FTIR） spectrometry,elemental analysis,and static light scattering.The thermodynamic properties of the copolymers were studied by thermogravimetric analysis（TGA）,and the effects of pH and the concentration of the copolymer on the average hydrodynamic radius（R h） were studied by dynamic light scattering（DLS）.In addition,the thermal sensitivities of the copolymers were studied by DLS and UV-Vis.The experiment data show that CB[6] beads are localized on 1,4-diaminobutane units in the side chains of the copolymer.TGA data show that thermal stability of the copolymers increases with the adding of CB[6] threaded because of the enhanced rigidity and the bulky steric hindrance of 4VBCB in the side chain of PNAM4VBCB.DLS data show that the average hydrodynamic radius of copolymer increases with the increase of the copolymer concentration and has a jump with adjusting pH due to the existing of the small size CB[6] dethreaded from the copolymer with increasing pH.Both pH and electrical conductivity curves of the solution of PNAM4VBCB-4 have a jump because CB[6] could dethread from the copolymers with the addition of NaOH.In addition,the copolymers have thermal sensitivity and their phase-change temperatures could be controlled by adjusting the molar ratio of NAM to 4VBCB in the copolymers.

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.

Bioinspired supramolecular macrocycle hybrid membranes with enhanced proton conductivity

Enhancing the proton conductivity of proton exchange membranes(PEMs)is essential to expand the applications of proton exchange membrane fuel cells(PEMFCs).Inspired by the proton conduction mechanism of bacteriorhodopsin,cucurbit[n]urils(CB[n],where n is the number of glycoluril units,n=6,7,or 8)are introduced into sulfonated poly(ether ether ketone)(SPEEK)matrix to fabricate hybrid PEMs,employing a nature-inspired chemical engineering(NICE)methodology.The carbonyl groups of CB[n]act as proton-conducting sites,while the host–guest interaction between CB[n]and water molecules offers extra protonconducting pathways.Additionally,the molecular size of CB[n]aids in their dispersion within the SPEEK matrix,effectively bridging the unconnected proton-conducting sulfonic group domains within the SPEEK membrane.Consequently,all hybrid membranes exhibit significantly enhanced proton conductivity.Notably,the SPEEK membrane incorporating 1 wt.%CB[8](CB[8]/SPEEK-1%)demonstrates the highest proton conductivity of 198.0 mS·cm^(−1) at 60°C and 100%relative humidity(RH),which is 228%greater than that of the pure SPEEK membrane under the same conditions.Moreover,hybrid membranes exhibit superior fuel cell performance.The CB[8]/SPEEK-1%membrane achieves a maximum power density of 214 mW·cm^(−2),representing a 140%improvement over the pure SPEEK membrane(89 mW·cm^(−2))at 50°C and 100%RH.These findings serve as a foundation for constructing continuous proton-conducting pathways within membranes by utilizing supramolecular macrocycles as fuel cell electrolytes and in other applications.

Fluorescent Nile blue-functionalized poly(N-isopropylacrylamide)microgels responsive to temperature and polyamines

Fluorescent poly(N-isopropylacrylamide-co-Nile blue)(pNIPAm-co-NB)microgels were synthesized that exhibited fluorescence intensity changes in a water temperature-dependent fashion.NB is well known to exhibit fluorescence intensity that depends on the hydrophobicity of the environment,while pNIPAm-based microgels are well known to transition from swollen(hydrophilic)to collapsed(relatively hydrophobic)at temperatures greater than 32℃;hence,we attribute the above behavior to the hydrophobicity changes of the microgels with increasing temperature.This phenomenon is ultimately due to NB dimers(relatively quenched fluorescence)being broken in the hydrophobic environment of the microgels leading to relatively enhanced fluorescence.We went on to show that the introduction of cucurbit[7]uril(CB[7])into the pNIPAm-co-NB microgels enhanced their fluorescence allowing them to be used for polyamine(e.g.,spermine[SPM])detection.Specifically,CB[7]forms a host–guest interaction with NB in the microgels,which prevents NB dimerization and enhances their fluorescence.When SPM is present,it forms a host–guest complex that is favored over the CB[7]-NB host–guest interaction,which frees the NB for dimerization and leads to fluorescence quenching.As a result,we could generate an SPM sensor capable of SPM detection down to~0.5µmol/L in complicated matrixes such as serum and urine.

Tomato leaf curl New Delhi virus:an emerging plant begomovirus threatening cucurbit production

Tomato leaf curl New Delhi virus(ToLCNDV),a bipartite begomovirus,was first reported to infect tomato and has recently spread rapidly as an emerging disease to Cucurbitaceae crops.To date,the virus has been reported to infect more than 11 cucurbit crops,in 16 countries and regions,causing severe yield losses.In autumn 2022,ToLCNDV was first isolated from cucurbit plants in Southeastern coastal areas of China.Phylogenetic analysis established that these isolates belong to the Asian ToLCNDV clade,and shared high nucleotide identity and closest genetic relationship with the DNA-A sequence from the Chinese tomato-infecting ToLCNDV isolate(Accession no.OP356207)and the tomato New Delhi ToLCNDV-Severe isolate(Accession no.HM159454).In this review,we summarize the occurrence and distribution,host range,detection and diagnosis,control strategies,and genetic resistance of ToLCNDV in the Cucurbitaceae.We then summarize pathways that could be undertaken to improve our understanding of this emerging disease,with the objective to develop ToLCNDV-resistant cucurbit cultivars.

Cucurbit[8]uril-mediated multi-color fluorescence system for time-dependent information encryption

Programming microscopic assembly mode to control macroscopic property is an attractive research objective.In particular,controlling molecular assembly to control fluorescence is of considerable interest for developing smart fluorescent materials.Herein,a color-tunable supramolecular emissive system was developed based on cucurbit[8]uril mediated host-guest assembly.Chemical designing for the molecular structures with minimized change resulted in different assembly modes and hence generating distinctive fluorescence,including green,yellow and orange with the addition of cucurbit[n]uril.Taking advantage of this feature,the advanced information encryption material(4D code)with multiple encryption levels and time-dependent encryption feature was developed.Such a code was dynamic on time scale,generating a series of 3D codes with time.The encrypted information only can be recognized by integrating time-coursed codes.This work provides a new insight for designing intelligent fluorescent materials for information encryption with high level of security.

Photoisomerization,assembling and fluorescence photoswitching behaviors of a water-soluble stiff-stilbene with cucurbit[7]uril

Photoresponsive supramolecular systems have merited extensive attention for their applications in materials science and life science.Here,we synthesized a water-soluble stiff-stilbene molecular photoswitch,exhibiting outstanding photoisomerization reaction between its(E)-and(Z)-configurations upon irradiation at distinct light.The photoswitch can assemble with cucurbit[7]uril(CB[7])to form a superior fluorescent supramolecular complex(compared to the only guest)with excellent water solubility,which manifested dramatic photoluminescence enhancement caused by restriction of intramolecular rotation and remained good photochromic characteristics.Furthermore,introduction of CB[7]influence photoreaction quantum yield(Φ)of the stiff-stilbene,leading to reduction ofΦ_(E→Z) and increase ofΦ_(Z→E) of the stiff-stilbene.Importantly,the photoadjustable supramolecular assembly can act as a fluorescence switch,and the phototunable guest further selectively modulate G-quadruplex structure of Tel22 upon light irradiation or with addition of CB[7].The study provides a new simple way for accurately regulating photochromic properties of molecular switches and developing smart materials with potential applications in controlled modulation of G-quadruplex,targeted biological imaging and so on.

Supramolecular assemblies of cucurbit[n]urils and 4-aminopyridine controlled by cucurbit[n]uril size(n=5,6,7 and 8)

The binding interactions between 4-aminopyridine(4-AP) and a series of cucurbit[n]urils(Q[5], Q[6],TMe Q[6], Q[7], Q[8]) have been studied using1H NMR spectroscopy, UV–vis absorption spectroscopy,isothermal titration calorimetry(ITC) and X-ray crystallography. The data indicates that the Q[5]@4-AP complex exhibits exo binding, which is not observed in the other four host-guest complexes. Furthermore,X-ray crystallography clearly reveals how the Q[n]s bind with 4-AP to form complexes, for example Q[5]forms an outer-surface complex, whilst Q[6], TMe Q[6] and Q[7] formed 1:1 host and guest type complexes, and Q[8] formed a stable 1:2 ternary complex due to its large cavity, which can accommodate two 4-AP molecules.

Hierarchically structured flower-like Ru nanoparticles-cucurbit[6]uril/multiwalled carbon nanotubes as efficient pH-universal hydrogen evolution electrocatalyst

Developing efficient and stable electrocatalyst to hydrogen evolution reaction adaptable for electrolytes with different p H is a big challenge.In this work,a hierarchically structured ternary nanohybrid composed of flower-like Ru nanoparticles,rigid macrocyclic cucurbit[6]uril(CB[6])and carboxylated multiwalled carbon nanotubes(MWCNTs)was successfully prepared by chemical wet method.Benefited by the structural merits of flower-like Ru nanoparticles exposed abundant active sites supported by the MWCNTs holding superior mass transport and electrons transfer ability as well as the existence of CB[6],the obtained catalyst exhibited outstanding HER activities with overpotentials of 27,37 and 70 m V at-10 m A/cm^(2) in alkaline,acidic,and neutral electrolytes,respectively.Under the same electrocatalytic operation conditions,the HER performance is comparable or superior to commercial Pt/C catalyst(47,27and 49 m V).Besides,chronopotentiometric and accelerated stability test also revealed its extraordinary stability,which could be further employed for electrocatalytic procedure in a broad pH range.

Electrochemical detection of amino acids based on cucurbit[7]uril-mediated three-dimensional gold nanoassemblies

In this paper, cucurbit[7]uril(CB[7])-mediated three-dimensional gold nanoassemblies were successfully prepared to increase the loaded amount of CB[7] and enhance the electrochemical detection of amino acids. Particle sizes of gold nanoparticles(Au NPs) significantly affect stability and detection sensitivity of nanoassemblies. The volume of gold nanoassemblies first increased and then decreased with the increase of CB[7] concentration. The 3D gold nanoassemblies composed of 16 nm Au NPs and 100 μmol/L CB[7]had excellent stability and maximum volume, exhibiting more sensitive detection for a variety of amino acids. And the detection limits of aromatic amino acids are lower in virtue of the higher binding constant between aromatic amino acids and CB[7]. This study will develop and deepen our understanding of molecular recognition in amino acids detection.

A novel pillar[5]arene-cucurbit[10]uril based host-guest complex: Synthesis, characterization and detection of paraquat

The macrocyclic family comprising pillar[n]arenes and cucurbit[n]urils have received much attention recently. However, studies on the construction of supramolecular complexes formed directly with derivatized pillar[n]arenes and cucurbit[n]urils are scant. Given the interest in such systems, herein we have synthesized a new type of naphthalene-derivatized pillar[n]arene NTP5 and selected Q[10] as the host molecule. The 4-[2-(1-naphthalenyl)ethenyl]pyridine of NTP5 is encapsulated by Q[10] and formed a hostguest complex in water-acetic acid(1:1) solution accompanied by enhanced fluorescence, which changed the morphology of NTP5 from a sphere to a porous form. In addition, the fluorescence of Q[10]-NTP5 can be quenched by the addition of the highly toxic pesticide paraquat(PQ), and the mechanism was shown to be the formation of a new charge transfer ternary system of Q[10]-NTP5-PQ. This work provides new ideas for the contribution of supramolecular assemblies based on derivatized pillar[n]arenes and their combination with cucurbit[n]urils and reveals their potential applications.

Reactive oxygen specie-induced photodynamic therapy activation by supramolecular strategy

Photodynamic therapy(PDT)agents may accumulate in skin and cause severe skin cytotoxicity.We report a pro-guest-based supramolecular strategy to selectively activate PDT in the reactive oxygen specie(ROS)overexpressed microenvironment,which is often existing in tumor and inflammatory tissues.PDT agents methylene blue(MB)and basic blue 17(BB17)are used as model drugs.When encapsulated by acyclic cucurbit[n]uril(CB[n]),the efficacy of PDT agents is significantly inhibited.By contrast,in the presence of ROS(H_(2)O_(2))and pro-guest,PDT agents are displaced and reactivated to show a dramatically enhanced PDT efficacy in cells.

Structural characteristics and the label-free detection of poly(3,4-ethylenedioxythiophene/cucurbit[7]uril)pseudorotaxane at single molecule level

A multi-technique approach to prove the preparation of poly(3,4-ethylenedioxythiophene/cucurbit[7]uril)pseudorotaxanes(PEDOT∙CB7-PPs)is reported.Molecular docking simulation and matrix-assisted laser desorption/ionization mass spectrometry(MALDI MS)validate the complexation ability of the CB7 molecule towards 3,4-ethylenedioxythiophene(EDOT),which leads to the EDOT∙CB7 inclusion complex.Oxidative polymerization of EDOT∙CB7 enabled the synthesis of PEDOT∙CB7-PPs.The water-soluble part of PEDOT∙CB7-PPs was selected,freeze-dried,and chemically characterized.Furthermore,dynamic light scattering(DLS)has been used to study the particle size and z-potential(ZP-ζ)of PEDOT∙CB7-PPs.The ZP-ζvalue(35 mV)evidenced that the PEDOT∙CB7-PPs formed stable water dispersion.By combining the emerging nanopore resistive pulse sensing technique(Np-RPS)and computational modeling,we identified strong interactions of PEDOT∙CB7-PPs with the aerolysin(Ael)nanopore.PEDOT∙CB7-PPs behave as positive charged species,and thus trans negative bias promotes its interactions with the Ael nanopore.The computational modeling results are fully consistent with the Np-RPS detection,which also reveals strong interactions between PEDOT∙CB7-PPs and the Ael nanopore.With this study,we hope to provide new insights and a better understanding of the interactions between supramolecular complexes based on CB7 and biological entities,which is instrumental for future applications in the field of nanobiotechnology.