Induced Resistance by the Toxin Filtrate of Bipolaris maydis Race T Cultivation

Resistance to maize southern leaf spot disease was induced by the low-concentration filtrate of Bipolaris maydis race T cultivation in an experiment. The nuclear neterogeny corn C103 was used as the test material. The lesion area on the leaves was significant difference by connalysis. The lesion areas on pretreated leaves were （0.3±0.05）- （0.9±0.5） mm^2, but those on the control were （23.1±8.7） mm^2. At the same time, the changes in peroxidase, phenylalanine, ammonialyase, and malondialdehvde activities were determined. During 0-96 h of inspection, phenylalanine and ammonialyase （PAL） activities increased by 64.2%, peroxidase （POD） activities increased by 41.2%, but the malondialdenvde （MDA） content decreased by 29.7% compared with the control. It seems that the low-concentration filtrate of Bipolaris maydis race T cultivation itself can be used as an elicitor to enhance the induced resistance.

Induced Resistance of Tomato against Gray Mold (Botrytis cinerea) by Salicylic Acid (SA)

[ Objective ] The paper was to explore the induced resistance of tomato against gray mold （Botrytis cinerea） by salicylic acid. [ Method ] SA was used as an inducer to treat tomato seedlings, the effects of SA on mycelial diameter and spore germination of B. cinerea were studied, and the changes of 4 defense enzyme activities containing catalase （CAT）, peroxidase （POD）, polyphenol oxidase （PPO） and phenylalanine ammonia lyase （PAL）, as well as malondialdehyde （MDA） content during the production process of induced resistance were also measured. [ Result] SA had no inhibitory effect against spore germination and myce- lial growth of B. cinerea within the concentration range, and the relative induced effect had different degrees of improvement after treatment. The induced effect was the best as B. cinerea was challenged to inoculate at the third day after using 150 mg/L SA in tomato plants, and the duration of resistance was 10 -15 d. After treated by SA, CAT, POD, PPO and PAL first increased and then decreased in systemic induced resistance against B. cinerea, which were significantly higher than control. Meanwhile, MDA content showed ascendant trend in wavy line form. [ Conclusion ] The use of SA within a certain concentration range is safe; CAT, POD, PPO and PAL activities have positive correlation with induced resistance against B. cinerea, the increase of MDA content also has close relationship with the imvrovement of disease resistance.

Evaluation of Selected Chemical,Biological Fungicides,and Induced Resistance to Control White Rot(Sclerotium rolfsii Sacc.)on Tomato

Tomato(Solanum lycopersicum)is one of the most widely grown and consumed as fresh vegetable in the world.Sclerotium rolfsii Sacc.is one of the most destructive diseases and affects more than 500 plant species.This study was conducted for“Evaluation of Selected Chemical,Biological Fungicides,and Induced Resistant to Control White Rot(Sclerotium rolfsii Sacc.)on Tomato”.The experiment was conducted at the Royal University of Agriculture and divided into two sections.The first section conducted under in vitro condition consists of four treatments T1 control treatment,T2 copper hydroxide,T3 azoxystrobin+difenoconazole,T4 metalaxyl+mancozeb in Nagoya Laboratory,and had been starting from 11st May to 15th May 2020.Section two was conducted in a pot in net-house which started from 1st January 2019 to 19th February 2019 and 1st January to 19th February 2020 and arranged in RCBD(Randomized Completely Block Design)with six replications and nine treatments.T0 negative control,T1 inoculate but not treatment,T2 metalaxyl+mancozeb,T3 azoxystrobin+difenoconazole,T4 copper hydroxide,T5 acibenzolar-S-methyl,T6 chicken dung+Trichoderma harzianum,T7 acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,T8 acibenzolar-S-methyl+metalaxyl+mancozeb.Data were collected on colonizing diameter in vitro.For pot experiment collected on disease incidence,incubation period Based on the result under in vitro condition metalaxyl+mancozeb highly inhibited germination of Sclerotium rolfsii when compared with another treatment.However,the application of copper hydroxide seems less effective compared with control.For in pot experiment,when treated after symptom of southern blight appeared to seem less effective on the severity of southern blight.In contrast,when applied as a protectant and curative when symptoms appeared only systemic fungicide azoxystrobin+difenoconazole significantly reduced the severity of Sclerotium rolfsii and delayed incubation period while compared with other treatments(p<0.05)and was followed by metalaxyl+mancozeb,whereas,copper hydroxide,acibenzolar-S-methyl,chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+chicken dung+Trichoderma harzianum,acibenzolar-S-methyl+metalaxyl+mancozeb were less effective(p>0.05).Based on the three experiments we can assume that fungicide is more effective in reducing the growth of the pathogen and delaying the incubation period of fungal colonization when compared with biological control and induced resistance.

Preliminary Studies on Induced Resistance of Cucumber to Downy Mildew

1 mL of sporangial suspensions (5 x 10 5spporangia per milliliter) of Pseudoperonospora cubensis was droplet-inoculated on the surface of the second leaf of the plant grown in greenhouse ( inducing inoculatoin), then the lower surfaces of the third, the forth and the fifth leaves were uniformly sprayed with inoculum of the same fungi (5 x 10 4sporangia per milliliter, about 5 mL per plant) every 3 days interval (challenge inoculation). Plants were moistened at 18- 22 C for 18 h, then kept at room temperature (24 - 28 C) and supplemented with cool-white fluorescent lights. All three challenge leaves were collected after 7 days of challenge to measure the amount of sporulation and area of necrosis. Plants prior inoculated with P. cubensis were protected 38% (based on the area of necrosis) against disaesc caused by subsequent foliar challenge with the pathogen. Protective action was about 12% after 3 days, and maintained this level until 9 days, suddenly reached 34% after 12 days, and came to a maximum after 15 days, then dropped down slowly.

Effects of β-Amino Butyric Acid Induced Rice Blast Resistance on Reactive Oxygen Metabolism

[Objective] This study was to understand the effects of β-Amino butyric acid(abbreviated as BABA) induced rice blast resistance on reactive oxygen metabolism. [Method] Using the cultivar Chaochan 2 that is highly susceptible to disease as experimental material, the changes of catalase(CAT), and superoxide dismutase(SOD) and MDA activities in rice treated by BABA were investigated. [Result] In rice plants treated by BABA, the activities of CAT and SOD increased, meanwhile the MDA content also rose to some extent, resulting in the disease resistance to rice blast. [Conclusion] By influencing reactive oxygen metabolism, BABA endows rice plants with resistance to rice blast. BABA is safe to environment and has highly resistance-inducing capacity, it could be generalized in production.

Tomato Resistance to Botrytis cinerea Induced by Chitosan

[Objective] The aim was to explore the effect of tomato＇s resistance to Botrytis cinerea induced by exogenous Chitosan.[Method] The leaf spraying method was used to determine the induced resistance effect of Chitosan to tomato B.cinerea and the chlorophyll content,soluble protein,soluble sugar,proline influence,the activities of peroxidase（POD）,malondialdehyde（MDA）and the Proline content in leaves of tomato.[Result] The induced resistance of Chitosan reached 58.26% at 14th d after treatment;Compared with the B.cinerea stress group,the chlorophyll content in leaves of tomato seedlings of B.cinerea stress ＋ Chitosan group had increased by 34.63%,while that of soluble protein content,soluble sugar content,Pro content and POD activity was 5.30%,10.83%,16.21% and 16.88%,respectively（except for the MDA content,which was decreased by 16.54%）.[Conclusion] Exogenous Chitosan could improve photosynthetic efficiency and protect enzymes activity to improve the resistance of tomato seedlings to B.cinerea.

Resistance -induced Effect of Several Chemical Reagents on Cucumber against Pseudoperonospora cubensis

[ Objectlve] The paper was to compare the induced resistance of several chemicals on cucumber against Pseudoperonospora cubensis [ Method ] When the cucumber seedlings grew to 4-leaf stage, the second true leaf was treated with salicylic acid, oxalate, chitosan, calcium nitrate and Na2HPO4, the activity of protective enzymes in the third leaf was determined after 7 d. At the same time, inoculation test was also conducted after induced treatment, and the disease condi- tion was coumed. [ Result ] These chemical treatments promoted protective enzyme activities （POD, SOD, PAL, PPO） in different degree, improved the ultra-weak luminescence, and reduced the disease index of cucumber leaves. [ Conclusion] Five chemical treatments expressed good effects on induced resistance. Among the treatments, oxalate had the best induced effect, followed by salicylic acid, chitosan, Na2 HPO4 and calcium nitrate.

Alternaria toxin-induced resistance in rose plants against rose aphid(Macrosiphum rosivorum): effect of tenuazonic acid

Many different types of toxins are produced by the fungus, Alternaria alternata （Fr.） Keissler. Little is known, however, regarding the influence of these toxins on insects. In this study, we investigated the toxin-induced inhibitory effects of the toxin produced by A. alternata on the rose aphid, Macrosiphum rosivorum, when the toxin was applied to leaves of the rose, Rosa chinensis. The results demonstrated that the purified crude toxin was non-harmful to rose plants and rose aphids, but had an intensive inhibitory effect on the multiplication of aphids. The inhibitory index against rose aphids reached 87.99% when rose plants were sprayed with the toxin solution at a low concentration. Further results from bioassays with aphids and high performance liquid chromatography （HPLC） analyses demon- strated that tenuazonic acid （TEA） was one of the most important resistance-related active components in the crude toxin. The content of TeA was 0.1199% in the crude toxin under the HPLC method. Similar to the crude toxin, the inhibitory index of pure TeA reached 83.60% 15 d after the rose plants were sprayed with pure TeA solution at the lower concentration of 0.060 IJg/ml, while the contents of residual TeA on the surface and in the inner portion of the rose plants were only 0.04 and 0.00 ng/g fresh weight of TeA-treated rose twigs, respectively, 7 d after the treatment. Our results show that TeA, an active component in the A. alternata toxin, can induce the indirect plant-mediated re- sponses in rose plants to intensively enhance the plant＇s resistances against rose aphids, and the results are very helpful to understand the plant-mediated interaction between fungi and insects on their shared host plants.

Different Proteomics of Ca^(2+) on SA-induced Resistance to Botrytis cinerea in Tomato

This study aims to comprehensively study the effects of Ca^(2+) on the SA-induced resistance Botrytis cinerea in tomato through proteomics analysis.A proteomic approach was used to uncover the inducible proteins of tomato in the susceptible tomato cultivars ‘L402' against Botrytis cinerea after salicylic acid(SA) and a combination treatment of CaCl_2 and SA.The results showed that the use of combination treatment of CaCl_2 and SA significantly enhanced tomato resistance against Botrytis cinerea.In total,46 differentially expressed protein spots from 2-DE gel maps were detected,of which 41 were identified by mass spectrometry.All the identified proteins were categorized into eight groups according to their putative functions:defense response(14.00%),antioxidative protein(9.75%),photosynthesis(24.39%),molecular chaperone(4.88%),energy(17.01%),metabolism(21.95%),protein synthesis(4.88%) and signal transduction(0.2%).Of the proteins in the eight function groups,the effect of stress/defense and reactive oxygen species on Ca^(2+) -regulated SA-induced resistance may be the most important one in induced resistance by RT-PCR.The expression level of pathogenesis-related proteins(PRs) and chitinase was upregulated by a combination treatment of CaCl_2 and SA.The characterization of these proteins greatly helped to reveal the induced proteins involved in the regulation of Ca^(2+) on SA-induced resistance to Botrytis cinerea.In the combination treatment of CaCl_2 and SA,the defense response and antioxidative protein were clearly upregulated much more than SA alone or the control treatment by the method of proteomics and RT-PCR.The present findings suggest that susceptible tomato cultivars treated by the combination treatment of CaCl_2 and SA might possess a more sensitive SA signaling system or effective pathway than SA treatment alone.In addition,results indicated that SA could coordinate other cellular activities linked with photosynthesis and metabolism to facilitate defense response and recovery,indicating that the self-defense capability of tomato was improved by the combination treatment of CaCl_2 and SA.

Advances in research of induced resistance to insects in cotton

Any change in a plant that occurs following herbivory or environmental factors is an induced response.These changes include phytochemical induction,increases in physical defenses,emission of volatiles that attract predators and parasitoids of herbivores,and reduction in plant nutritional quality for herbivores,which is termed induced resistance.Induced resistance has been demonstrated ubiquitously in plants.It is one of our goals to review what is known about the induced resistance to herbivorous insects in cotton,including three resistance secondary metabolites(terpenoid,tannin,and flavonoids)that are contained at any significant levels of resistance to herbivorous insects in cotton cultivates.In many cases,the quantities or quality of secondary metabolites in plant are changed after attacked by insects.This review focuses on induced plant resistance as quantitative or qualitative enhancement of defense mechanism against insect pests,especially on the abiotic-elicitors-induced resistance in cotton plants.The abiotic-elicitor of cupric chloride,an exogenous inorganic compound,may induce the secondary metabolites accumulation and is referred to as a copperinducible elicitor(CIE).Finally,we discuss how copperinducible elicitor may be used in the Integrated Pest Management(IPM)system for cotton resistance control.

The role of signal production and transduction in induced resistance of harvested fruits and vegetables

Postharvest diseases are the primary reason causing postharvest loss of fruits and vegetables.Although fungicides show an effective way to control postharvest diseases,the use of fungicides is gradually being restricted due to safety,en vironmental polluti on,and resista nee developme nt in the pathogens.Induced resista nee is a new strategy to control postharvest diseases by eliciti ng immune activity in fruits and vegetables with exogenous physical,chemical,and biological elicitors.After being stimulated by elicitors,fruits and vegetables respond immediately against pathoge ns.This process is actually a conti nuous signal tra nsducti on,in eluding the generati on,transduction,and interact!on of signal molecules.Each step of response can lead to corresponding physiological functi ons,and ultimately induce disease resista nee by upregulating the expressi on of disease resista nee genes and activati ng a variety of metabolic pathways.Signal molecules not only mediate defe nse resp onse alone,but also in teract with other signal tra nsducti on pathways to regulate the disease resista nee resp on se.Among various signal molecules,the sec ond messenger(reactive oxygen species,nitric oxide,calcium ions)and plant hormones(salicylic acid,jasmonic acid,ethylene,and abscisic acid)play an importa nt role in induced resista nee.This article summarizes and reviews the research progress of induced resista nee in recent years,and expounds the role of the above-me ntioned signal molecules in induced resista nee of harvested fruits and vegetables,and prospects for future research.

A Triterpenoid Inhibited Hormone-Induced Adipocyte Differentiation and Alleviated Dexamethasone-Induced Insulin Resistance in 3T3-L1 adipocytes

6a-Hydroxylup-20(29)-en-3-on-28-oic acid(1),a natural triterpenoid,was found to possess the ability in a dose-dependent manner inhibiting hormone-induced adipocyte differentiation in 3T3-L1 preadipocytes,and restoring glucose consuming ability in dexamethasone(DXM)-induced insulin resistant 3T3-L1 adipocytes.Compound 1 was also found to ameliorate DXM-induced adipocyte dysfunction in lipolysis and adipokine secretion.Mechanistic studies revealed that 1 inhibited adipocyte differentiation in 3T3-L1 preadipocytes via down-regulating hormone-stimulated gene transcription of peroxisome proliferator-activated receptor c and CCAAT-enhancer-binding protein alpha which are key factors in lipogenesis,and restored DXM-impaired glucose consuming ability in differentiated 3T3-L1 adipocytes via repairing insulin signaling pathway and activating down-stream signaling transduction by phosphorylation of signaling molecules PI3K/p85,Akt2 and AS160,thus leading to increased translocation of glucose transporter type 4 and transportation of glucose.

2,3-Butanediol from the leachates of pine needles induces the resistance of Panax notoginseng to the leaf pathogen Alternaria panax

Compared with the use of monocultures in the field,cultivation of medicinal herbs in forests is an effective strategy to alleviate disease.Chemical interactions between herbs and trees play an important role in disease suppression in forests.We evaluated the ability of leachates from needles of Pinus armandii to induce resistance in Panax notoginseng leaves,identified the components via gas chromatography-mass spectrometry(GC-MS),and then deciphered the mechanism of 2,3-Butanediol as the main component in the leachates responsible for resistance induction via RNA sequencing(RNA-seq).Prespraying leachates and 2,3-Butanediol onto leaves could induce the resistance of P.notoginseng to Alternaria panax.The RNA-seq results showed that prespraying 2,3-Butanediol onto leaves with or without A.panax infection upregulated the expression of large number of genes,many of which are involved in transcription factor activity and the mitogen-activated protein kinase(MAPK) signaling pathway.Specifically,2,3-Butanediol spraying resulted in jasmonic acid(JA)-mediated induced systemic resistance(ISR) by activating MYC2 and ERF1.Moreover,2,3-Butanediol induced systemic acquired resistance(SAR) by upregulating pattern-triggered immunity(PTI)-and effector-triggered immunity(ETI)-related genes and activated camalexin biosynthesis through activation of WRKY33.Overall,2,3-Butanediol from the leachates of pine needles could activate the resistance of P.notoginseng to leaf disease infection through ISR,SAR and camalexin biosynthesis.Thus,2,3-Butanediol is worth developing as a chemical inducer for agricultural production.

Molecular Basis of Transfer of Induced Resistance in Plants

Two brown spot disease resistant varieties of tobacco, named NC89 V1 and NC89 V2, were obtained by first inducing from disease sensitive NC89 with the two hypovirulent viruses ToMV N14 and CMV SV52, then tissue culturing the plants and finally seed breeding. The disease resistance for both varieties was verified to be stable in three generations. The transcription activities of five plant defense response genes, pr 1a, chi, chs, pal, and lox, in NC89, NC89 V1, and NC89 V2 were studied through RNA blot hybridization. Genome DNA structural differences among the three tobacco lines were identified using randomly amplified polymorphic DNA(RAPD).

Blast Resistance of Rice Induced by Ag-antibiotic 702

To explore rice blast resistance induced by Ag-antibiotic 702, different concentrations of Ag-antibiotic 702 were spayed on susceptible variety Luliangyou 996 at three-leaf and one-heart stage, to screen the optimal concentration for inducing rice blast resistance. Ag-antibiotic 702 was sprayed at seven different growth stages of rice, to determine the best growth stage for induced blast resistance and duration of blast resistance. Various treatments were inoculated with spore fluid of Magnaporthe grisea at 4 d post spraying, and disease index and incidence rate as well as induction effect of different treatments were investigated after 7 d. The results showed that six concentrations of Ag-antibiotic 702 could induce rice resistance against blast, and 15 μg/mL led to the highest blast resistance; spraying 15 μg/mL Ag-antibiotic 702 at seven different growth stages could induce rice resistance against blast ; the three-leaf and one-heart stage was the best growth stage for inducing rice blast resistance, and the relative induction effect reached 56.56% ; rice blast resistance was the highest at 48 -96 h post spraying, and duration of induced rice blast resistance exceeded 144 h. The study will provide useful experimental data for further development of Ag-antibiotic 702 and application of pre- vention and control methods against rice blast.

Study on Exogenous Ethylene Induced Rice Resistance to Rhizoctonia solani

Rice sheath blight is one of the main diseases in rice production in China,which can make rice unable to absorb and utilize nutrients,and has a serious impact on rice yield and quality.In this study,exogenous ethylene was used to induce rice resistance against rice sheath blight,aiming at exploring a new environment-friendly control method of rice sheath blight.The results showed that within a range of certain concentrations,ethylene had no significant effects on mycelium growth,but it could induce resistance to sheath blight in rice.The optimum concentration was 0.2 mmol•L^(-1) and the relative control was 86.17%.It was found that ethylene could effectively increase the activities of peroxidase(POD),phenylalanine ammonia-lyase(PAL),β-1,3-glucanase and reduce the contents of malondialdehyde(MDA),which could enhance the resistance of rice against Rhizoctonia solani.In addition,qRT-PCR detected the expressions of rice defense genes,which indicated that the expressions of the POX,PAL and OsPR1b genes were up-regulated.

Resistance and Reactance of Monopole Fields Induced by a Test Charge Drifting Off-Axis in a Cold and Collisional Cylindrical Plasma

We study the interaction of a uniform, cold and collisional plasma with a test charged particle moving off-axis at a constant speed down a cylindrical tube with a resistive thick metallic wall. Upon matching the electromagnetic field components at all interfaces, the induced monopole electromagnetic fields in the plasma are obtained in the frequency domain. An expression for the plasma electric resistance and reactance is derived and analyzed numerically for some representative parameters. Near the plasma resonant frequency, the plasma resistance evolves with frequency like a parallel RLC resonator with peak resistance at the plasma frequency pe, while the plasma reactance can be capacitive or inductive in nature depending on the frequency under consideration.

Stimulatory Effect of Tithonya diversifolia-by Products on Plantain Banana Vivoplants in Nursery (A Review)

Plantain banana is an important cash crop that serves as stable food for millions of people around the world and contributes to income generation. Indeed, they provide a major staple food crop for millions of people and play an important role in the social fabric of many rural communities. Plantain banana cultivation encounters major problem of seedlings unavailability that are essential for the creation of new plantations, as well as parasitic constraints. Mycosphaerella fijiensis is the main pathogen attack constraints of banana plant responsible of black Sigatoka disease, and viruses, which can severely reduce the photosynthetic leaf area, leading to banana production losses of more than 80% in plantations with soil fertility problems. The repeated use of synthetic input is the origin of contamination to the environment, different pollution sources of plants and human health, as well as resistance to some strains of pathogens and plant fertilization problems over time. Recent works carried out in nursery have shown that vivoplants of plantains treated with biostimulants based on natural products notably Tithonia diversifolia biopromote good growth and less susceptibility to M. fijiensis. Indeed, an increase in agromorphological characteristics, good accumulation of growth and defense biomarkers was also observed. In this context, Tithonia diversifolia is shown to be involved in the stimulatory effect mechanism of growth promotion and defensive reaction of plantain vivoplants against various pathogens and it is suggested to be acting as a vital stimulator. This article reviews the current state of knowledge on plantain banana cultivation constraints and on the potential of Tithonia diversifolia in relation with its different stimulatory effects on plantain vivoplants.

Effects of Exogenous Salicylic Acid Derivative on the Resistance to TMV and Activity of Defense Enzymes of Tobacco

[Objective] This study aimed to evaluate the effects of exogenous salicylic acid derivatives on tobacco resistance to TMV and activity of defense enzymes. [Method] The tobboco leaves were treated by exogenous salicylic acid derivatives. Then, the disease occurrence was observed, and the activity of phenylalanin ammo- nia lyase （PAL） and peroxidase （POX） were measured. [Result] Exogenous salicylic acid derivative increased the activities of PAL and POX, while did not influence the resistance to TMV. [Conclusion] The result provides a theoretical basis for the study of plant disease resistance mechanisms.

A change of phenolic acids content in poplar leaves induced by methyl sali-cylate and methyl jasmonate

The contents of seven different phenolic acids such as gallic acid, catechinic acid, pyrocatechol, caffeic acid, coumaric acid, ferulic acid and benzoic acid in the poplar leaves （Populus Simonii×Populus Pyramibalis c.v and Populus deltoids） suffocated by Methyl jasmonate （MeJA） and Methyl salicylate （MeSA） were monitored for analyzing their functions in interplant communications by using high-pressure liquid chromatography （HPLC）.The results showed that the contents of phenolic acids had obviously difference in leaves exposed to either MeSA or MeJA.When P.deltoides leaves exposed to MeJA or MeSA, the level of gallic acid, coumaric acid, caffeic acid, ferulic acid and benzoic acid was increased, gallic acid in leaves treated with MeJA comes to a peak at 24 h while to a peak at 12-d having leaves treated with MeSA.When P.Simonii ×P.Pyramibalis c.v leaves were exposed to MeJA or MeSA, the level of gallic acid, pyrocatechol and ferulic acid was increased; The catechinic acid and benzoic acid had a little drop; The caffeic acid and coumaric acid were undetected in both suffocated and control leaves.This changed pattern indicated that MeJA and MeSA can act as airborne signals to induce defense response of plants.