Toxicity of fenpropimorph to fenarimol-resistant isolates of Penicillium italicum

Fenarimol-resistant isolates ofPenicillium italicum with cross-resistance to imidazole and triazole fungicides which inhibit ergosterol biosynthesis were tested for their sensitivity to fenpropimorph. Radial growth tests on PDA showed that the isolates (n=6) lacked cross-resistance to fenpropimorph or displayed enhanced sensitivity to the fungicide (negatively correlated cross-resistance). Control of blue mold decay of oranges incited by the wild-type isolate could be achieved by dipping fruits in suspensions of fenpropimorph at a concentration of 100 mg ml^–1. Decay of oranges incited by the fenarimol-resistant isolates was controlled at the same or at a lower concentration (30 mg ml^–1), thus showing that the normal or increased sensitivity to fenpropimorph is also expressed under in vivo conditions.Samenvatting Fenarimol-resistente isolaten vanPenicillium italicum met kruisresistentie tegen imidazool-en triazoolfungiciden die de ergosterolbiosynthese remmen, werden getoetst op hun gevoeligheid voor fenpropimorf. Radiale groeiproeven op PDA toonden aan dat de isolaten (n=6) geen kruisresistentie bezaten met fenpropimorf of een verhoogde gevoeligheid voor het middel vertoonden (negatief gecorreleerde kruisresistentie). Op sinaasappels konPenicillium-rot, veroorzaakt door het wild-type bestreden worden door middel van een dompelbehandeling met fenpropimorf bij een dosering van 100 g ml^–1). Bestrijding van rot veroorzaakt door fenarimil-resistente isolaten werd verkregen bij dezelfde of een lagere dosering (30 g ml^–1); aldus werd aangetoond dat de normale of verhoogde gevoeligheid voor fenpropimorf ook in vivo tot uiting komt.     

甘肃地方苜蓿农家品种脯氨酸积累能力与抗旱性的研究

本文依据“脯氨酸维持积累时间”和“脯氨酸维持积累量”指标评介了四个甘肃地方苜蓿农家品种的抗旱能力。结果表明:敦煌苜蓿的抗旱能力高于会宁、秦安、灵台苜蓿,其中会宁苜蓿居二,灵台苜蓿抗旱性最差。这一抗旱排序与叶片相对含水量及气孔指标所得到的结果相一致。证明了“脯氨酸维持积累时间”和“脯氨酸维持积累量”可以作为首蓿抗旱性的鉴定指标。     

水稻苗田化学除草剂—封闭1号大面积苗田药效示范试验结果

通过多点水稻苗田大面积示范试验结果表明,通化市农科所研制的水稻苗田除草剂“封闭1号”具有除草效果好(90～100％)、安全、使用方便、成本低等特点。1988～1991年,累计推广面积(苗田)达15.6万亩,创造经济效益150万元。     

“七五”国家科技攻关项目——蔬菜新品种选育研究Ⅳ.甜(辣)椒专题育成的新品种(系)简介

本文介绍了1986-1990年甜(辣)椒专题8个单位育成的15个甜椒、半辛辣椒新品种(系),其抗病性、品质、产量均优于对照品种,并已通过了农业部主持的专家组验收。     

Genetic mapping and utilization of quantitative trichome-mediated insect resistance in potato

Introgression of trichome-mediated insect resistance from the wild speciesSolanum berthaultii has become a major focus of the potato improvement program at Cornell University during the past twelve years. Several quantitative characters are involved in this resistance which is effective against a wide range of pest types. Correlative biochemical assays have been developed to assay specific components of the resistance, and the effects of the resistance on the target pests have been studied. Quantitative laboratory assays and specific measurements of insect behavior and biology have increased the precision of selection and enable the investigation of the genetic control of the resistance.We are currently using restriction fragment length polymorphisms (RFLPs) for genetic mapping of factors controlling the trichome traits fromS. berthaultii. Backcrosses to both the wild and the cultivated species parents have been evaluated for phenotypes contributing to the resistance mechanism, including trichome density, sucrose ester and polyphenol oxidase production by the trichomes, and the enzymatic browning reaction responsible for insect entrapment. Genetic maps are being developed for these progenies, using RFLP markers previously mapped in potato. Field and greenhouse trials under insect infestations are also being conducted with the mapping progeny. Our goal is to locate genes responsible for quantitative insect resistance by correlating RFLP variation at mapped loci with the trichome phenotypes and insect resistance. Genetic markers for these traits will be useful in transfer of the effective wild chromosomal segments into and among tetraploid potatoes, and for a better understanding of the resistance mechanism.     

Prospects for improving potato crop protection against aphid vectors

Conventional ways to control aphid vectors on potato crops rely essentially on cultural and chemical methods. The extensive use of insecticides, too often applied regardless of real needs and consequences, has resulted in more and more failures in both controlling aphids and virus spread. This paper stresses the need to introduce more rationale in the operation of existing methods by improving the efficiency of some of them like forecasting systems, to assess the potential of others like fertilization and semiochemicals and to put most efforts on resistant cultivars so that integrated pest management can be operated in the near future.     

Resistance to bifenthrin and resistance mechanisms of different strains of the two-spotted spider mite (Tetranychus urticae) from Turkey

Nine different strains of the two-spotted spider miteTetranychus urticae Koch (Acari: Tetranychidae) were collected on cotton from Adana, Antalya, Izmir, Manisa and Urfa in Turkey. Their responses to bifenthrin were investigated using conventional bioassay and biochemical assays. LC₅₀ and LC₉₀ values of bifenthrin were determined for all strains by using a residual bioassay with a petri dish-spray tower. Resistance ratios were determined by comparing the samples with a standard susceptible strain, GSS. The resistance ratios of the strains ranged from <1 to 669-fold (at LC₅₀). Of the investigated field strains, only three (two from Adana and one from Urfa) were resistant to bifenthrin. There was a correlation between esterase enzyme activity and bifenthrin resistance according to polyacrylamide gel electrophoresis and microtiter plate assays in the three resistant strains. http://www.phytoparasitica.org posting May 17, 2005.     

Age-related resistance to Pseudomonas syringae pv. tomato is associated with the transition to flowering in Arabidopsis and is effective against Peronospora parasitica

As plants mature it has been observed that some become more resistant to normally virulent pathogens. The ability to manifest the Age-Related Resistance (ARR) response in Arabidopsis to Pseudomonas syringae pathovars tomato (Pst) coincided with the transition to flowering in plants both delayed and accelerated in the transition to flowering. ARR was also associated with a change in PR-1 gene expression, such that young plants expressed PR-1 abundantly at 3 days post inoculation (dpi) while mature plants expressed much less. The Arabidopsis ARR response requires SA accumulation via isochorismate synthase (ICS1) [24]. ICS1 was expressed one dpi with virulent and avirulent Pst in both young and mature plants. The ARR response was also effective versus avirulent Pst providing an additional 4-fold limitation in bacterial growth. Arabidopsis ARR was found to be ineffective against two necrotrophs, Erwinia carotovora subspecies carotovora (bacterium) and Botrytis cinerea (fungus) and one obligate biotroph, Erysiphe cichoracearum (fungus). However, mature wild type, SA-deficient sid2 and NahG plants supported little growth of the obligate biotrophic oomycete, Peronospora parasitica. Therefore ARR to P. parasitica appears to be SA-independent, however the level of ARR resistance was somewhat reduced in these mutants in some experiments. Thus, there may be numerous defence pathways that contribute to adult plant resistance in Arabidopsis.     

Molecular cloning, expression, and characterization of a phi-type glutathione S-transferase from Oryza sativa

The structural gene for glutathione S-transferase in Oryza sativa was successfully cloned from a cDNA library by the polymerase chain reaction method. The deduced amino acid sequence of this gene showed 44-66% similarity to the sequences of the class phi GSTs from Arabidopsis thaliana and Zea mays. This gene was expressed in Escherichia coli with the pET vector system and the gene product was purified to homogeneity by GSH-Sepharose affinity column chromatography. The expressed OsGSTF3-3 was a homo-dimer composed of 24 kDa subunit and its pI value was approximately 7.3. The OsGSTF3-3 was retained on GSH affinity column and its K_m value for GSH was 0.28 mM. The OsGSTF3-3 displayed high activity toward 1-chloro-2,4-dinitrobenzene, a general GST substrate and also had high activities towards acetanilide herbicides, alachlor, and metolachlor. The OsGSTF3-3 was highly sensitive to inhibition by benastatin A and S-hexyl-GSH. From these results, the expressed OsGSTF3-3 is a phi class GST and seems to play an important role in the conjugation of the chloroacetanilide herbicides.