Screening and evaluation for antibiosis resistance of the spring wheat accessions to the grain aphid,Sitobion miscanthi(Takahashi)(Hemiptera:Aphididae)

Resistant cultivar deployment is an effective method for cereal aphid management.Under greenhouse conditions,preliminary antibiosis resistance screening was conducted on 114 Ethiopian and 22 Chinese spring wheat accessions.After performing a bioassay to determine antibiosis resistance,aphid feeding behaviour and phenolic acid content analyses were performed on the aphid resistant wheat accessions by electrical penetration graph(EPG)and high performance liquid chromatography(HPLC),respectively.Among the wheat accessions,two high resistances,27moderate-resistances,and 35 low-resistances to Sitobion miscanthi were identified.The antibiosis resistance test showed prolonged pre-adult and pre-reproductive periods,shorter reproductive periods,lower fecundity,an intrinsic rate(rm)of increase,and a finite rate(λ)of increase of S.miscanthi on Lunxuan 145,Wane,Lunxuan 6,204511,Lunxuan 103and 5215 than those on the aphid-susceptible accession Beijing 837.The changes for the parameters of aphid feeding behaviour,including spending a longer time in the penetration and phloem salivation phases and less time in the phloem sap-feeding phase on the resistant wheat accessions,indicated that the aphid resistance may occur during the phloem phase and may be due to difficulties in the mechanical probing of the mesophyll cells.Additionally,the HPLC analysis showed higher contents of:1)ferulic acid in Lunxuan 145,Lunxuan 103 and Lunxuan 6;2)p-coumaric acid in Lunxuan145;3)vanillic acid in Lunxuan 145,Wane and Lunxuan 6;4)syringic acid in Lunxuan 103;and 5)caffeic acid in 5215.The contents of some phenolic acids within wheat leaves,such as p-courmaric acid and vanillic acid showed significant positive correlation with the duration of aphid development,but negative correlation with the aphid fecundity.The concentrations of these acids may be the causes of antibiosis resistance to S.miscanthi.The identification of grain aphid-resistant wheat accessions in our study will be helpful in future breeding program for pest control.

Study on the antibiosis of exudate JK-91-b against rice sheath blight (SHB)

Antagonistic bacterial strain 91-b possessedstronger antagonistic ability against SHBinfection. The control effects of the bacterizationagainst SHB were 58.1% in greenhouse and 45.1%in paddy. The effect of antibiosis JK-91-b exudat-ed by strain 91-b was studied in the present re-search.Bacterial strain 91-b was inoculated into

Immobilization of pegylated AMP on hydroxyapatite nanorods for antibiosis

Infection is one of the major reasons whichinduce failure of percutaneous Ti implants.Covalent bonding of antimicrobial peptides(AMPs)on Ti surfaces can avoid AMPs'blast release by physical absorption,but the reduced mobility affects their antibacterial efficiency.In this paper,HHC36 was pegylated with PEG12 and immobilized on hydroxyapatite(HA)nanorods to endow Ti surface with antibacterial activity and improved cytocom-patibility simultaneously.The obtained results indicated that HA nanorods immobilized with HHC36 showed antibacterial activity,and pegylation obviously increased the antibacterial activity of immobilized HHC36 against staphylococcus aureus.They reached 99.5%and 97.0%in vitro and in vivo,respectively.PEG12 is flexible,and it increases mobility of HHC36 and enables lateral diffusion of peptide molecules into the lipid double layer of microbial membrane,resulting in highly antibacterial activity of HHC36.Furthermore,HA nanorods immobilized with pegylated HHC36 have reduced inflammatory response in an infection model and should be potentially applied on percutaneous Ti implants for reducing infection-induced failure and enhancing biointegration.

Identification of Soybean Resources of Resistance to Aphids

Four soybean [Glycine max （L.） Merr.] cultivars with soybean aphid resistance （Aphis glycines Matsmura）, p189, P203, P574, and P746, were identified in field test, choice test, and non-choice test, The grade of resistance to aphids and the damage index of P189, P203, and P746 were significantly different from the susceptible cultivars （P=0.05）. P574 and P746 showed antibiosis resistance, preventing aphids from reproducing on the plants. P203 showed antixenosis resistance, preventing aphids from reproducing in field test and choice test, but susceptible in non-choice test. Population development on plants was significantly different in field test, choice test, and non-choice test, which was caused by different selective pressures.

Evaluation of Rice Germplasm for Resistance to the Small Brown Planthopper (Laodelphax striatellus) and Analysis of Resistance Mechanism

One hundred and thirty-eight rice accessions were screened for resistance to the small brown planthopper （SBPH） （Laodelphax striatellus Fallen） by the modified seedbox screening test. Twenty-five rice accessions with different levels of resistance to SBPH were detected, accounting for 18.1% of the total accessions, which included 2 highly resistant, 9 resistant and 14 moderately resistant varieties. Compared with indica rice, japonica rice was more susceptible to SBPH. Antixenosis test, antibiosis test and correlation analysis were performed to elucidate the resistance mechanism. The resistant check Rathu Heenati （RHT）, highly resistant varieties Mudgo and Kasalath, and resistant variety IR36 expressed strong antixenosis and antibiosis against SBPH, indicating the close relationship between resistance level and these two resistance mechanisms in the four rice varieties. Antibiosis was the dominant resistance pattern in the resistant varieties Daorenqiao and Yangmaogu due to their high antibiosis but low antixenosis. Dular, ASD7 and Milyang 23 had relatively strong antixenosis and antibiosis, indicating the two resistance mechanisms were significant in these three varieties. The resistant DV85 expressed relatively high level of antixenosis but low antibiosis, whereas Zhaiyeqing 8 and Guiyigu conferred only moderate antibiosis and antixenosis to SBPH, suggesting tolerance in these three varieties. Antibiosis and antixenosis governed the resistance to SBPH in the moderately resistant accession 9311. Antixenosis was the main resistance type in V20A. Tolerance was considered to be an important resistance mechanism in Minghui 63 and Yangjing 9538 due to their poor antibiosis and antixenosis resistance. The above accessions with strong antibiosis or antixenosis were the ideal materials for the resistance breeding.

Alleviating Effect of Phenol Compounds on Cucumber Fusarium Wilt and Mechanism

The amount of phenol compounds in the soil increased after adding organic material into the soil. It was found that p-hydroxybenzoic acid, p-coumaric acid and frulic acid alleviated Fusarium wilt of cucumber, the alleviating effect of p-hydroxybenzoic acid was the best, followed by p-coumaric acid and frulic acid. The total amount of bacterial, actinomyces and fungus in high phenol compounds treatment decreased than that of control treatment, while the microorganisms’ amount in low phenol compounds treatment increased. Phenol compounds inhibit the growth of pathogen.

Activity of Secondary Bacterial Metabolites in the Control of Citrus Canker

This study investigated the protective effects of secondary bacterial metabolites, produced by Pseudomonas sp. (bacterium strain LN), on citrus canker disease caused by Xanthomonas axonopodis pv. citri (Xac 306). The LN bacteria strain was cultured in liquid medium and the supernatant free-cells was treated with methanol (AMF) and ethyl acetate (AEF), respectively, and then the extract was concentrated, filtrated, lyophilized and fractionated by vacuum liquid chromatography (VLC). After VLC, eight fractions were obtained. All fractions’ activity against Xac 306 by agar well diffusion assay and minimum inhibitory concentration but in different concentrationswere tested. Cytotoxicity effects were observed in all fractions in 50 μg·mL-1 concentration. The comet assay demonstrated that the fractions EAF, VLC2 and VLC3 presented no genotoxic effects at tested concentrations. In plants only VLC3 showed significant results (p<0.05), reducing the incidence of citrus canker lesions.

Isolation and Identification of three Lactobacilli and Research on Antimicrobial Activity in Vitro

Collected from the broiler cecal contents, bacteria were isolated and purified. These isolated and purified Lactobacilli were detected by acidity and bile salt tolerant test, then three better tolerant strains were screened out. These three strains were conducted to observe the morphous through microscope, perform Gram stain, and to identify their physiological and biochemical characteristics. The results showed that L1 was L.casei, L2 was L.gasseri and L3 was L.graminis. With Oxford Cup method, these three Lactobacilli were detected for their bacteriostasis. Results showed that L1, L2 and L3 strains had strong antibacterial activities to E. coli and Salmonella.

Nature of Gene Action and Maternal Effects for Pod Borer, <i>Helicoverpa armigera</i>Resistance and Grain Yield in Chickpea, <i>Cicer arietinum</i>

Information on mechanisms and inheritance of resistance is critical to plan an effective strategy to breed for resistance to insect pests. Therefore, we evaluated a diverse array of chickpea genotypes (eight desi and one kabuli) with varying levels of resistance to the pod borer, Helicoverpa armigera to gain an understanding of the nature of gene action and possible maternal effects. The test genotypes were crossed in all possible combinations for a full diallel. The 72 F1s (36 direct and 36 reciprocal crosses) along with the parents were evaluated for resistance to H. armigera under field conditions, and for antibiosis mechanism of resistance (larval survival and larval weight gain) by using detached leaf assay under laboratory conditions, and grain yield under un-protected conditions in the field. Additive gene action governed the inheritance of resistance to H. armigera, while non-additive type of gene action was predominant for inheritance of antibiosis component of resistance (larval survival and larval weight) and grain yield. Greater magnitude of σ2 A(17.39 and 1.42) than σ2 D (3.93 and 1.21) indicated the preponderance of σ2 Ain inheritance of resistance to pod borer, H. armigera under laboratory and field conditions, respectively. There were no maternal effects for inheritance of resistance to pod borer and grain yield. Lines with significant gca effects for pod borer damage and grain yield were identified for further use in the resistance breeding program. The implications of the inheritance pattern of pod borer resistance and grain yield are discussed in the context of strategies to enhance pod borer resistance and grain yield in chickpea.

Management of <i>Helicoverpa armigera</i>(Lepidoptera: Noctuidae) by Nutritional Indices and Botanical Extracts of <i>Millettia ferruginea</i>and <i>Azadirachta indica</i>

The development of hosts that are resistant and evaluation of botanical extracts to H. armigera Hübner (Lepidoptera: Noctuidae) is crucial for sustainable management, yet very limited in Ethiopia. Therefore, this study was done to identify alternative methods to insecticide control through host consumption study and botanical extracts. The performance of third-fifth larval stages of H. armigera on three host plant varieties including chickpea, tomato and faba bean and botanical extracts against the third larval instars and oviposition deterrence was studied under laboratory condition (22°C ± 2°C, 55% ± 5% RH, 12:12 L: D photoperiod). Significant differences were found in the efficiency of conversion of ingested food (ECI%) (F = 80.06;df = 6, 2;p H. armigera reared on the three host plant varieties of the whole larval instars. The minimum relative consumption rate (RCR) (11.271 ± 0.328) and maximum approximate digestibility (AD) (177.9 ± 1.928) values of the whole larval instars were on Dagaga and Koshari, respectively. The values of relative growth rate (RGR), ECI% and ECD% of the whole larval instars were highest on chickpea varieties and lowest on tomato Koshari. Among chickpea varieties, Habru was relatively resistant to larval instars of H. armigera. Botanical extracts at 50% neem oil (NO), 5% birbira seed extract (BSE) and 5% neem seed extract (NSE) (18.4%) resulted superior in larval mortality however, statistically not different. At both 5% and 2.5% concentration level of botanical extracts the minimum larval mortality was recorded from neem leaf extract (NLE). Maximum numbers of eggs were laid on control treatments and the minimum eggs were on 5% BSE. The deterrent effect of 50% neem oil was stronger (ODI = 17.66%) than that of 5% BSE (ODI = 14%) which is statistically similar value with 5% NSE (ODI = 13%). In conclusion, the result indicated that use of Habru chickpea variety with 50% NO was very effective in controlling both the larvae and deterring the adults of H. armigera from egg lying. These measures could be important in the wider managements of H. armigera by integrating host resistance and botanical extracts.

Microenvironment-responsive electrocution of tumor and bacteria by implants modified with degenerate semiconductor film

Implantable biomaterials are widely used in the curative resection and palliative treatment of various types of cancers.However,cancer residue around the implants usually leads to treatment failure with cancer reoccurrence.Postoperation chemotherapy and radiation therapy are widely applied to clear the residual cancer cells but induce serious side effects.It is urgent to develop advanced therapy to minimize systemic toxicity while maintaining efficient cancer-killing ability.Herein,we report a degenerate layered double hydroxide(LDH)film modified implant,which realizes microenvironment-responsive electrotherapy.The film can gradually transform into a nondegenerate state and release holes.When in contact with tumor cells or bacteria,the film quickly transforms into a nondegenerate state and releases holes at a high rate,rendering the“electrocution”of tumor cells and bacteria.However,when placed in normal tissue,the hole release rate of the film is much slower,thus,causing little harm to normal cells.Therefore,the constructed film can intelligently identify and meet the physiological requirements promptly.In addition,the transformation between degenerate and nondegenerate states of LDH films can be cycled by electrical charging,so their selective and dynamic physiological functions can be artificially adjusted according to demand.

A HAase/NIR responsive surface on titanium implants for treating bacterial infection and improving osseointegration

Bacterial infection and insufficient osseointegration are critical factors affecting the long-term success of titanium-based implants.Unfortunately,the direct application of antibiotic on Ti implants easily leads to poor cytocompatibility,as well as the production of drug-resistant bacteria.So,in this work,we designed a prospective antibacterial strategy by combining photothermal and ciprofloxacin(CIP).The synergistic effect of photothermal and antibiotic may provide an effective bacteriostatic efficacy without sacrificing osteogenesis at a mild condition of moderate temperature and less antibiotic.Herein,CIP was loaded into mesoporous polydopamine(MPDA)nanoparticles(MPDA@CIP),which were anchored on the surface of titanium and finally covered with sodium hyaluronate-catechol(HAc)coating.The hydrophilic HAc layer could inhibit the early adhesion of bacteria,and some bacteria could secrete bacterial hyaluronidase to accelerate the degradation of HAc.This enabled smart enzyme-triggered release of antimicrobials at the site of infection on-demand and avoided unwanted side effects on normal tissues.In addition,NIR light irradiation had a positive influence on both CIP release and MPDA nanoparticle’s photothermal effect.Moreover,before anchoring MPDA@CIP,by the construction of hydroxyapatite microstructure on Ti sur-face with micro-arc oxidation and alkali heat treatment,the ability of bone formation of Ti could be promoted also.Both in vitro as well as in vivo assays demonstrated that functional Ti has an excellent antibacterial effect and osteogenic ability.

Reevaluating the conceptual framework for applied research on host-plant resistance

Applied research on host-plant resistance to arthropod pests has been guided over the past 60 years by a framework originally developed by Reginald Painter in his 1951 book, Insect Resistance in Crop Plants. Painter divided the ＂phenomena＂ of resistance into three ＂mechanisms,＂ nonpreference （later renamed antixenosis）, antibiosis, and tolerance. The weaknesses of this framework are discussed. In particular, this trichotomous framework does not encompass all known mechanisms of resistance, and the antixenosis and antibiosis categories are ambiguous and inseparable in practice. These features have perhaps led to a simplistic approach to understanding arthropod resistance in crop plants. A dichotomous scheme is proposed as a replacement, with a major division between resistance （plant traits that limit injury to the plant） and tolerance （plant traits that reduce amount of yield loss per unit injury）, and the resistance category subdivided into constitutive/inducible and direct/indirect subcategories. The most important benefits of adopting this dichotomous scheme are to more closely align the basic and applied literatures on plant resistance and to encourage a more mechanistic approach to studying plant resistance in crop plants. A more mechanistic approach will be needed to develop novel approaches for integrating plant resistance into pest management programs.

A Highly Efficient Aggregation-induced Emission Photosensitizer for Photodynamic Combat of Multidrug-resistant Bacteria

With the antibiotic abuse and the resulting increased antibiotic resistance,the bacterial infection has posed a serious threat to human health.Photodynamic therapy is an effective tool for treating localized and superficial infections.It is a promising approach for the treatment of superbugs and with minimal risk of induced antibiotic resistance.Herein,an isoquinolinium-based photosensitizer,LIQ-TPE,with aggregation-induced emission properties is designed and synthesized.It is with high 1O2 generation efficiency and shows efficient antibacterial performance towards both Gram-negative and Gram-positive bacteria,and even methicillin-resistant Staphylococcus aureus(MRSA).LIQ-TPE thus shows great promise as an effective antimicrobial agent to combat the menace of multi-drug resistant bacteria.

Resistance of stored bean varieties to Acanthoscelides obtectus （Coleoptera： Bruchidae）

During bean seed storage, yield can be lost due to infestations of Acanthoscelides obtectus Say, the bean weevil. The use of resistant varieties has shown promising results in fighting these insects, reducing infestation levels and eliminating chemical residues from the beans. The expression of resistance to A. obtectus in bean varieties is frequently attributed to the presence of phytohemagglutinins, protease inhibitors and alpha-amylase, and especially to variants of the protein arcelin, which reduce the larval viability of these insects. To evaluate the effect of bean seed storage time on the resistance expression of bean varieties to A. obtectus, tests with seeds of three ages （freshly-harvested, 4-month-old, and 8-monthold） were conducted in the laboratory, using four commercial varieties： Carioca Pitoco, Ipa 6, Porrillo 70, Onix; four improved varieties containing arcelin protein： Arc. 1, Arc.2, Arc. 3, Arc.4; and three wild varieties also containing arcelin protein： Arc.lS, Arc.3S, and Arc. 5S. The Arc.5S, Arc.lS, and Arc.2 varieties expressed high antibiosis levels against the weevil; Arc.1 and Arc3S expressed the same mechanism, but at lower levels. The occurrence of oviposition non-preference was also observed in Arc.5S and Arc. 1S. The Arc.3 and Arc. 4 varieties expressed low feeding non-preference levels against A. obtectus. The expression of resistance in arcelin-bearing, wild or improved varieties was affected during the storage of seeds, and was high under some parameters but low in others. The results showed that addition of chemical resistance factors such as protein arcelin via genetic breeding may be beneficial in improving the performance of bean crops.