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1.
Since July 1974Nicotiana tabacum ‘Samsun NN’ plants, inoculated with the common strain of tobacco mosaic virus (TMV), have occasionally been found to develop necrosis on non-inoculated upper leaves 2–7 days after the local necrotic lesions had appeared on the lower leaves. All these plants had been kept in a growth chamber at 17–20°C. Other tobacco species and cultivars carrying theN gene, such asN. glutinosa andN. tabacum ‘Xanthi-nc’, showed the same phenomenon. Substantial amounts of TMV could be recovered from leaves with systemic symptoms. The systemic necrosis somewhat resembled that caused by tobacco rattle virus (TRV). A number of possible causes, such as high concentration of the inoculum, contamination with another strain of TMV or with TRV, change in the genetic composition of the host plants and certain growing conditions (soil, water, pesticides) were investigated. None of these factors could be held fully responsible for the abnormal systemic reaction, although there was evidence that the soil could sometimes play an important rôle.  相似文献   

2.
The effect of meturine on the light processes of photosynthesis was studied.Meturine is a herbicide for weed control in potato and cotton crops. It is a N-phenyl—N-hydroxy—N′-methylurea.The experiments were carried out on isolated pea and spinach chloroplasts.When examining photosystem I, reduced DPIP was used as an electron donor, whereas methyl-viologen served as an electron acceptor. When examining photosystem II, DPIP represented the electron acceptor.The obtained experimental results have pointed to the absence of the effect of meturine upon the photoreaction I.Unlike N-phenyl—N′, N′-dimethylureas (CMU, DCMU) meturine has been a very weak inhibitor of photoreaction II.The authors explain the photoreaction II inhibition of chloroplasts from plants treated with herbicidal doses of meturine by conversion of N-phenyl—N-hydroxy—N′-methylurea into Hill reaction inhibitor(s). N-Phenyl—N′-methylurea can be one of such meturine metabolites.Meturine herbicidal action is accounted for by meturine transformation into Hill reaction inhibitor(s) in the plant tissues.  相似文献   

3.
[14C]Buturon, a urea herbicide, was sprayed on soil and winter wheat as an aqueous formulation (2.98 kg/ha) under outdoor conditions. Three months after application, a total of 49.2% of the applied radiocarbon was recovered: 46.9% in the soil, 0.3% in the leaching water (depth > 50 cm), and 2.0% in the plants. Radioactive residues in the soil were distributed to a depth of 50 cm and decreased with increasing depth of the soil. An average of 47% of the radioactivity present in the soil could be extracted with cold chloroform; by this extraction method, the formation of artefacts was avoided. Between one and two thirds of the extracted radioactivity was unchanged buturon. In the soil extracts, the following eight conversion products were isolated and identified by combined gas chromatography/mass spectrometry: N-(p-chlorophenyl)-N-methyl-O-methyl carbamate; N-(p-chlorophenyl)-O-methyl carbamate; N-(p-chlorophenyl)-N′-methyl-N′-isobutenyl-urea; N-(p-chlorophenyl)-N′-methyl-urea, N-(p-chlorophenyl)-N′-methyl-N′-isobutenylol-urea; p-chloroaniline in “biologically bound” form; N-(p-chlorophenyl)-N′-methyl-N′-methoxyisobutenyl-urea; and N-(p-chlorophenyl)-N′-methyl-N′-ethoxyisobutenyl-urea. In the leaching water, which contained only 0.005–0.006 mg/liter of radioactive substances, the following three conversion products were isolated and identified by gas chromatography/mass spectrometry: p-chloroformanilide; N-(p-chlorophenyl)-N-methyl-O-methyl carbamate; and an N-hydroxyphenyl-N′-methyl-N′-isobutinyl-urea. The results are discussed in relation to the factors responsible for the formation of these products.  相似文献   

4.
Preliminary studies were undertaken to establish the occurrence of Turnip mosaic virus (TuMV) resistance phenotypes in 99 Brassica napus and 32 B. carinata accessions, breeding lines and cultivars mostly from Africa, Australia, the Indian sub-continent or China. An isolate of TuMV pathotype 8 (WA-Ap1) was used in most inoculations. The influence of temperature on expression of resistance phenotypes was determined. Those identified were O (extreme resistance), RN (localised hypersensitivity), R (resistance to systemic movement without necrosis), +N (systemic infection with some necrosis), + (susceptibility), and RN/+ (systemic infection with necrosis limited to inoculated leaves). In the initial glasshouse evaluations with B. napus, 18 lines developed phenotype O, 42 RN, two + (both from Australia), and 30 segregated for O and RN, two for R and RN, one for O and R, two for O, R and RN, one for O, RN and +N, and one for RN and +N. Phenotype +N only occurred in two lines from India. In the initial glasshouse evaluations with B. carinata, 14 lines developed O, two RN or R, and one +; the 13 remaining lines segregated for phenotypes O and R (12), or RN and R (1). In B. carinata, phenotype RN only occurred in African lines, and phenotype + only in a line from Pakistan. The 18 B. napus and 14 B. carinata lines that developed phenotype O uniformly were re-evaluated at low (16 and/or 18 °C) and high (25 °C) temperatures in the glasshouse three or two times, respectively, and again under controlled environment room conditions at 16 and at 28 °C. While in most lines phenotype O was replaced by other phenotypes or segregated with other phenotypes at the higher temperatures, it occurred uniformly regardless of temperature in Chinese B. napus line (06-6-3777) and three African B. carinata lines (IP 117, ST 18 and ST 50). Graft inoculations confirmed extreme resistance in these four lines. Other promising lines which displayed phenotype O in >75 % of inoculated plants included for B. napus Chinese lines 06-p71-1 and 06-p74-4 and French line Cresor, and for B. carinata African lines Mbeya Green, ML-EM-1, ML-EM-7 and ML-EM-8, and Australian lines P 195923.3 and 30200533. Five promising lines segregated for phenotype RN, B. napus Ding 110, Hyola 42, Fan 028, ZY 007 and Qu 1104. Chinese B. napus line Ding 110 developed phenotype RN uniformly at high (25 and 28 °C) temperatures. Thus, in plants developing phenotypes RN, R and +, low temperature retarded virus multiplication in inoculated leaves to below the level at which it can be identified using ELISA. No clear phenotypic differences attributable to TuMV pathotype were found in tests in which isolates from pathotypes 1, 7 and 8 were used. This highlights the need for future evaluations for TuMV resistance in Brassica germplasm to be done at higher temperatures. This study also highlights the need to identify additional genes responsible for the different resistance and susceptibility reactions found, especially in B. carinata. The four lines that developed phenotype O uniformly at all temperatures and also withstood graft-inoculation will be particularly valuable for developing new TuMV-resistant cultivars of oilseed and forage Brassicas.  相似文献   

5.
During a survey of virus diseases affecting pepper grown in plastic houses in Crete, during 1984–1986, tomato mosaic virus (ToMV) and tobacco mosaic virus (TMV) were detected. The most common virus was TMV, being present in samples of alle pepper cultivars carrying the L1 resistance gene, while ToMV was isolated only from susceptible pepper cultivars. According to responses ofCapsicum spp. the isolates from 640 samples checked were classified into three pathotypes: P0, P1.2 and P1.2.3. Results of this study show that P1.2 represents at present the major threat to the Cretan pepper industry.Samenvatting Bij een in de jaren 1984–1986 gehouden inventarisatie van virusziekten in paprika in plastic-foliekassen op Kreta werd zowel het tabaksmozaïekvirus (TMV) als het tomatemozaïekvirus (ToMV) aangetoond. TMV kwam zeer algemeen voor: het werd aangetroffen in alle monsters van de paprikarassen met het resistentiegen L1. ToMV werd alleen geïsoleerd uit planten van vatbare paprikarassen. Volgens de waargenomen symptomen die de isolaten van 640 monsters opCapsicum spp. vertoonden, konden de isolaten in drie pathotypen, nl. P1, P1,2 en P1,2,3, worden geklassificeerd. Uit het onderzoek is gebleken dat P1,2 de belangrijkste bedreiging vormt voor de teelt van paprika op Kreta.  相似文献   

6.
The effects of chlordimeform [N-(2-methyl-4-chlorophenyl)-N′,N′-dimethylformamidine] on amine regulatory mechanisms in insects were studied. Chlordimeform inhibits monoamine oxidase (MAO) from cockroach heads in vitro, and the MAO substrates serotonin and norepinephrine accumulate in poisoned insects in vivo. Chlordimeform synergizes the toxicity of tryptamine, another MAO substrate. The significance of these findings in relation to the mode of action of chlordimeform is discussed.  相似文献   

7.
An insect chitin synthetase (CS) is readily assayed using the microsomal fraction (～0.5 mg protein) from an homogenate of Tribolium castaneum larvae. This enzyme preparation is incubated at 22°C with uridine 5′-diphospho-N-acetyl[3H]glucosamine in 355 μl of 25 mM Tris-HCl buffer containing 10 mM MgCl2, 17 mM N-acetylglucosamine, and 1 mM dithiothreitol. Other divalent cations and amino sugars are less effective activators or are inhibitory. T. castaneum CS is strongly inhibited by polyoxin D and uridine 5′-diphosphate. These activation and inhibition properties of Tribolium castaneum gut CS are similar to those of fungal CS. The polymerization product formed by the Tribolium enzyme is stable in alkali but hydrolyzed by chitinase. Enzymes of Tribolium confusum, Tribolium brevicornis, Tenebrio molitor, and Galleria mellonella are also active under the same conditions. These enzymes are from the gut and probably from the peritrophic membrane. Integumental CS activity is not detected under the indicated assay conditions.  相似文献   

8.
Families of interspecific hybrids between Salix dasyclados and S. viminalis, and intraspecific hybrids of the two species, were monitored for rust infection caused by Melampsora epitea during the years 1997–1999. The resistance of interspecific hybrids was compared to intraspecific pure species halfsibs. In addition, uredospores were sampled from the most infected interspecific hybrids to determine whether rust from interspecific hybrids differed from the rust spores that infected the pure species. The results from 1997 and 1999 showed that interspecific hybrids were more resistant than the intraspecific pure species, thus exhibiting a pattern of hybrid resistance. In 1998 the interspecific hybrids showed intermediate resistance compared to intraspecific pure species hybrids, i.e., an additive pattern of resistance. The rust sampled from the interspecific hybrids consisted of the same types of rust that infect the pure species. Comparisons of weather conditions prevailing during the three growing seasons indicated that these conditions might play a role in the infection pattern, in addition to the level of sensitivity to infection shown by the plants.  相似文献   

9.
为了寻找新型具有抗烟草花叶病毒 (TMV) 作用的化合物,在前期研究工作基础上,以取代苄胺、氨基酸及亚膦酸二烷基酯等为原料,按照由C端向N端依次接肽的合成策略,采用缩合剂O-苯并三氮唑-四甲基脲六氟膦酸酯 (HBTU) 合成酰胺的方法,获得了18个新型寡肽手性膦酸酯硫脲,其结构均经红外光谱、(1H、13C、31P、19F) NMR及元素分析确证和表征,并首次研究了该类化合物抗TMV活性。结果表明:部分目标物对TMV具有较高治疗作用,其中化合物 5i 、 5j 和 5p 在500 μg/mL时对TMV侵染的活体治疗作用效果分别为52.6%、55.7%和56.1%,接近对照药剂宁南霉素 (55.4%)。值得进一步结构改造和构型优化,并在此基础上进行作用机制研究。  相似文献   

10.
Failure to control Alternaria late blight in a few California pistachio orchards was observed after only 3-4 years of consecutive applications of azoxystrobin-based fungicide programs. A total of 72 isolates of Alternaria alternata, Alternaria tenuissima, and Alternaria arborescens, the causal organisms of Alternaria late blight, were collected from pistachio orchards with (58 isolates) and without (14 isolates) a prior history of azoxystrobin applications. The sensitivity to azoxystrobin was determined in conidial germination assays. Isolates from orchards with a history of azoxystrobin applications had EC50 values greater than 100 μg/ml, whereas isolates from orchards without a prior history of azoxystrobin usage had EC50 values ranging from 0.008 to 0.045 μg/ml. Azoxystrobin resistance correlated with a single mutation in the cytochrome b (cyt b) gene causing a change of glycine to alanine at amino acid position 143. A pair of PCR primers AF and AR was developed that amplified a 226-bp DNA fragment of the cyt b gene containing the mutation site from all three Alternaria species but not from 30 other fungal species frequently found on pistachio. PCR-restriction fragment length polymorphism (PCR-RFLP) analysis using the restriction enzyme Fnu4HI allowed differentiation of the PCR fragment of wild type cyt b gene from that of mutated gene. This method will aid in a fast detection of azoxystrobin resistance in these three Alternaria species.  相似文献   

11.
Relationships between three types of herbicidal activity of N′-substituted phenyl-N-methoxy-N-methylureas and substitution at the benzene ring were analyzed by the Hansch-Fujita method. First, the Hill inhibitory activity was correlated with electronic (σ) as well as hydrophobic (π) substituent constants. The existence of an optimum value of hydrophobicity for substituents was suggested to reach the target site of action. Second, bliaching activity observed for the 3-substituted but not for 4-substituted compounds was correlated with π, σ, and steric substituent constant, Es. Third, the postemergent herbicidal activity was shown to correlate linearly with the Hill inhibitory activity, pI50, and hydrophobic parameter, π.  相似文献   

12.
We constructed a SSH (suppression subtractive hybridization) library based on two populations (Rs-C and Rs-P) of Radopholus similis from different host plants and exhibiting differences in pathogenicity on Musa paradisiaca and Anthurium andraeanum plants. In order to screen the clones with significant expression differences from the SSH library, a total of 2,400 clones was randomly selected and reverse northern blotting was performed on them. Out of the 2,400 clones, 89 clones showed significant expression differences. Out of sequencing these 89 clones, distinct sequences from 87 clones were obtained. Aligning the 87 distinct sequences against the non-redundant nucleotide database (nr) in NCBI, we found that five sequences were highly conserved with Rs-eng-1b. Two of five sequences with lengths of 467 base pairs (bp) (GW395922) and 742?bp (GW395923) were further employed to perform 5′ RACE-PCR and 3′ RACE-PCR, respectively. Subsequently, the complete length of Rs-eng-1b (EU414839) was obtained (1,427?bp). Our qPCR result showed that expression of Rs-eng-1b in the population Rs-C with high pathogenicity on host plants was approximately 2.7 times as much as the expression of Rs-eng-1b in the population Rs-P with low pathogenicity on host plants. Furthermore, the gene Rs-eng-1b from the Rs-C population also showed expression differences amongst four different development stages. The order of Rs-eng-1b relative expression abundance from high to low was females, juveniles, males, and eggs. We further used RNAi to test whether Rs-eng-1b of Rs-C population was responsible for pathogenicity which was the first RNAi work about Rs-eng-1b. The RNAi results showed that Rs-eng-1b expression had a positive correlation to pathogenicity of the population. The longer the RNAi treatment, the less pathogenic the nematode population was. Non-endogenous gfp dsRNA had no significant influence on the expression of Rs-eng-1b and pathogenicity of R. similis Rs-C population. In conclusion, all our evidence indicated Rs-eng-1b might be a crucial pathogenicity-related gene in R. similis.  相似文献   

13.
Photo-induced fungitoxicity was observed in Alternaria alternata, Aspergillus niger, Cladosporium variabile, Colletotrichum sp., Rhizopus nigricans, Pythium aphanidermatum, and Saprolegnia sp., elicited by 5-(but-3-en-l-ynyl)-2,2′-bithienyl, 2,2′: 5′,2″-terthienyl, and 2-chloro-4-[5-(penta-1,3-diynyl)-2-thienyl]but-3-ynyl acetate in the presence of near ultraviolet (u.v.) radiation (320–380 nm). Conidiogenesis in A. niger, and sporangiosporogenesis in R. nigricans were depressed on media treated with 2,2′: 5′,2″-terthienyl and irradiated with near u.v. light. Radial growth of mycelia of all fungi tested was dramatically reduced by all three compounds in the presence of near u.v. light. The viability of conidia of A. niger, and R. nigricans was unaffected by 2,2′: 5′,2″-terthienyl, both in the dark and in near u.v. light. Newly emergent germ-tubes were most sensitive to toxicity mediated by u.v. light. The oomycetous fungi tested were the most sensitive to the photo-activated toxicity generated by the three compounds used. The results indicate that ED50 values are dependent upon the species and the presence or absence of near u.v. light. Dramatically lowered ED50 values were always observed in all systems treated with near u.v. light. The dose of near u.v. light used had no effect on the radial growth of fungi in the absence of the three compounds.  相似文献   

14.
The activity of two groups of growth regulators, substituted dinitroanilines and nitrophenylhydrazines, were evaluated in a tobacco (Nicotiana tabacum L. “X-73”) callus tissue bioassay. Molar concentrations required to inhibit fresh weight gain by 50% (I50) was determined by using linear regression analysis on data obtained by testing a range of five concentrations of each chemical. All chemicals tested were inhibitory to callus tissue grown in the dark. Cell division seemed to be the primary activity inhibited. The most active of the dinitroaniline series was α,α,α-trifluoro-2,6-dinitro-N-ethyl-N-2′,6′-dichlorobenzyl-p-toluidine (I) (I50 = 1.5 × 10?10M). I and two other N-(o-halobenzyl) dinitroanilines were more active than α,α,α-trifluoro-2,6-dinitro-N-ethyl-N-2′-chloro-6′-fluorobenzyl-p-toluidine (IV), which is being developed commercially for suppression of axillary buds in tobacco. The two most active nitrophenylhydrazines tested were 1,1-dimethyl-2-(2′,6′-dinitro-3′-n-propylamino-α,α,α-trifluoro-p-tolyl)hydrazine (XVIII) and 3′,5′-dinitro-p-(2,2-diethylhydrazino)-N-methoxy-N-methylbenzamide (XIX) (I50 values of 7.9 × 10?9 and 9.3 × 10?9M, respectively). Factors such as electronic distribution, steric hindrance, and lipid solubility were considered to influence the biological activity of the compounds tested.  相似文献   

15.
The herbicide monuron (N-(4-chlorophenyl)-N′, N′-dimethylurea)—a recognized carcinogen—and some of its congeners have been found also to induce back mutations in Salmonella typhimurium (Ames test), as well as micronuclei in mouse bone marrow cells and an inhibition of testicular DNA synthesis (DSI test) in mice. As both the Ames test and the DSI test correlate well with chemical carcinogenicity, urea herbicides in general might be suspected of carcinogenic activity. In order to investigate the potential carcinogenic mode of action of these substances we looked for possible activation mechanisms. The reaction sequence N-oxidation-esterification-carbonium ion formation seemed the only one able to fit the observed structure-activity relationships. Chemical synthesis of the proposed N-acetoxy compounds provided the means for testing this hypothesis. Only the N-acetoxy-, but neither the N-hydroxy- nor the unchanged parent ureas, exhibited a direct alkylating action as measured by the NBP-assay. The DSI reactivity pattern of several positional isomers could be shown to coincide with the theoretical predictions, as did the stability of the chloroisomers in aqueous solution at pH 7. Furthermore the N-acetoxy derivatives could be demonstrated to behave in the Ames test as directly acting mutagens, while the activity of the parent compounds is dependent on the metabolic activation by an S-9-liver fraction. The enhancing action of Acetyl-CoA on the S-9 mediated mutagenicity of these ureas can then be regarded as the final proof for the proposed reaction sequence.  相似文献   

16.
Enzymatically isolated leaf cells from navy beans (Phaseolus vulgaris L., cv. “Tuscola”) were used to study the effect of buthidazole (3-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-4-hydroxy-1-methyl-2-imidazolidinone) and tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N′-dimethylurea) on photosynthesis, protein, ribonucleic acid (RNA), and lipid synthesis. The incorporation of NaH14CO3, [14C]leucine, [14C]uracil, and [14C]acetic acid as substrates for the respective metabolic process was measured. Time-course and concentration studies included incubation periods of 30, 60, and 120 min and concentrations of 0.1, 1, 10, and 100 μM of both herbicides. Photosynthesis was very sensitive to both buthidazole and tebuthiuron and was inhibited in 30 min by 0.1 μM concentrations. RNA and lipid syntheses were inhibited 50 and 87%, respectively, by buthidazole and 42 and 64%, respectively, by tebuthiuron after 120 min at 100 μM concentration. Protein synthesis was not affected by any herbicide at any concentration or any exposure time period. The inhibitory effects of buthidazole and tebuthiuron on RNA and lipid syntheses may be involved in the ultimate herbicidal action of these herbicidal chemicals.  相似文献   

17.
The inheritance of resistance toFusarium oxysporum f.sp.cucumerinum race 1 was determined in the cucumber cv. WIS-248 by analyzing segregation of F1, F2, and BC populations of crosses with the susceptible cv. Straight-8. Resistance was conferred by a single dominant gene. In an allelism test, it was proven that theFcu-1 gene, which confers resistance toF. oxysporum f.sp.cucumerinum races 1 and 2 in cucumber cv. SMR-18 and theFoc gene, which confers resistance toF. oxysporum f.sp.cucumerinum race 2 in cucumber cv. WIS-248, are indistinguishable.  相似文献   

18.
In the Japanese quail, cytochrome P-450, A- and B-esterase, amidase, and glutathione S-aryl transferase were assayed in postmitochondrial centrifugal fractions, in microsomes, and supernatant fractions of liver, lungs, kidneys, and testes. Liver microsomes contained the highest A-esterase activity and P-450 levels. B-esterase was more generally distributed and higher in the microsomal tissue fractions. Microsomal amidase activity was highest in quail lung and kidney, and lowest in the liver (per mg protein). Very little difference in glutathione S-aryl transferase activity was noted among the tissues assayed. In vitro metabolism of carbaryl, phosphamidon, and chlorotoluron by the various centrifugal fractions revealed that the production of 1-naphthyl-N-hydroxymethylcarbamate and 1-naphthol, the major metabolites, was greatest in the postmitochondrial fraction of the liver. The major carbaryl metabolite in all other quail tissue fractions was 1-naphthol. Phosphamidon metabolism in postmitochondrial preparations of quail liver was higher than in the supernatant and microsomes. Chlorotoluron metabolism occurred only in the postmitochondrial fractions of quail liver. The major products were the oxidative metabolites, N-(3-chloro-4-methylphenyl)-N′-methylurea and N-(3-chloro-4-hydroxymethylphenyl)-N′-methylurea.  相似文献   

19.
通过2 a田间试验,研究陕北黄土高原沟壑区滴灌水量和追施氮量对苹果生长指标、产量和品质的影响,优化苹果灌水量和追施氮量,以达到节水、节肥和高产优质的目的。试验设置4个灌溉水平：高水（W1：100%I,I为计算灌水量）、中水（W2：80%I）、低水（W3：60%I）和不灌水W4,各处理追施氮量均为230 kg·hm-2（N2）,探究最优灌水量;设置4个追施氮水平：高氮（N1：施纯氮0.69 kg·棵-1,约合345 kg·hm-2）、中氮（N2：施纯氮0.46 kg·棵-1,约合230 kg·hm-2）、低氮（N3：施纯氮0.23 kg·棵-1,约合115 kg·hm-2）和不施氮N4,各处理灌水量均为80%I（W2）,探究最优追施氮量。试验结果表明,灌水量和追施氮量对苹果生长、产量和品质影响显著。W1N2、W2N2和W3N2处理2 a平均叶片相对含水率比W4N2分别增加了7.5%、6.3%和2.5%,各追施氮处理的追施氮量对叶片相对含水率影响不显著。叶片SPAD值随生育期的变化呈现出先增加后减小的趋势,2 a的SPAD值均在W1N2处理取得最大值,平均为61.30。W2N2处理能显著增加横径70~80 mm和＞80 mm的苹果产量和苹果总产量,提高优果率。W1N2处理2 a的单果重均最大,平均为212.86 g,W2N2处理的单果重为210.20 g,与W1N2无显著差异。W2N2处理维生素C含量在2 a间均取得最大值,平均为5.6 mg·（100g）-1,比W1N2增加2.7%,比W2N1增加11.6%。W1N2、W2N2和W3N2处理2 a平均可溶性固形物分别比W4N2处理减少11.3%、4.9%和2.5%,W2N1、W2N2、W2N3处理2 a平均可溶性固形物分别比W2N4处理减少11.7%、9.7%和4.8%。W1N2处理平均可溶性糖含量为11.53%,仅比W2N2增加2.4%。2年W1N2处理的可滴定酸均为最小,平均为0.35%,与W2N2处理不存在显著差异。全面考虑果树生长、产量、品质及节水节肥等因素,W2N2处理为该研究区较优的苹果灌水和追施氮策略。  相似文献   

20.
Studies on polymer size, concentration and mode of application, either as foliar spray or soil drench, in relation to the induction of resistance to tobacco mosaic virus (TMV) in Nicotiana tabacum cv xanthi-nc by poly(acrylic acid) (PA) are reported. PA also induced resistance to TMV in N. glutinosa, to pelargonium leaf curl virus in Datura stramonium, to cucumber mosaic virus in Vigna sinensis and to tobacco ring-spot virus in N. tabacum cv White Burley. No TMV was detected in PA-treated tomato cv Virocross 11 days after inoculation; but the susceptible cultivar Craigella became infected. PA treatment had no effect on TMV replication in White Burley tobacco but resistance was induced to Peronospora tabacina, a fungal pathogen of N. tabacum cv xanthi-nc. The potential of PA-induced resistance as a control measure for viruses and fungi is discussed.  相似文献   

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