Victoria Blight,defense turned upside down

Genes that confer disease resistance to biotrophic pathogens typically encode nucleotide-binding, leucine-rich-repeat proteins (NB-LRRs). These proteins confer resistance by detecting the presence of virulence effectors secreted by biotrophic pathogens. Recognition triggers NB-LRR activation and subsequently, the defense response which often includes localized host cell death. The fungus, Cochliobolus victoriae, is a necrotrophic pathogen that causes a disease called Victoria Blight. Virulence of this fungus is dependent on its production of a peptide called “victorin” that has been traditionally described as a toxin. Only plants that respond to victorin are susceptible to Cochliobolus victoriae whereas those that do not are resistant to the fungus. Genetic and molecular analyses have revealed that victorin functions like a biotrophic effector recognized by a NB-LRR resistance protein in Arabidopsis. Further, numerous plant species express victorin sensitivity suggesting there are numerous NB-LRRs that recognize victorin. Thus, through expression of victorin, C. victoriae is able to exploit plant defense to cause disease and is capable of evoking this response in an array of different plants.     

大豆品种的再生性能及对EHA 101农杆菌的敏感性

大豆转化可利用农杆菌和子叶节转化系统,bar基因作为选择标记,草丁膦作为选择试剂.用5-6 d发芽的种子的子叶节作外植体,在子叶节处划5-6下,用含pPTN 140的农杆菌EHA 101感染后,共培养3 d,用含抗生素的洗液洗去外植体上的农杆菌,将外植体放入5 mg/L草丁膦的长芽培养基,两周后统计不同大豆品种的再生率,4周后做GUS染色对含pPTN1     

小麦收获前种子发芽敏感性配合力的研究

选用5个收获前穗发芽敏感性不同的白皮小麦亲本品种,进行双列杂交,研究了发芽敏感性的配合力。结果表明:小麦收获前种子发芽敏感性同时受加性和非加性基因效应影响,而加性基因效应起主导作用;亲本品种发芽敏感性的一般配合力存在极显著差异,杂交组合的特殊配合力和反交效应方差则有时显著,有时不显著;白皮小麦杂交当代种子,以     

磺酰脲除草剂对不同作物的敏感度测定

经室内药剂对种子胚根长度抑制测定，结果表明：玉主胚根是甲磺隆、绿磺隆、苯磺隆的敏感试材。１４个小麦品种对甲磺隆、烟嘧磺隆的敏感程度不同，经方差分析差异显著。烟农１５对甲磺隆最敏感，其ＩＣ５０值为０．１１７１ｍｇ／ｋｇ；河农１号对甲磺隆最不敏感，其ＩＣ５０值为５．３１４０ｍｇ／ｋｇ。河农３２６对烟嘧磺隆最敏感，其ＩＣ５０值为０．０４５３ｍｇ／ｋｇ；河北２００对烟嘧磺隆最不敏感，其ＩＣ５０值为６．９２     

Variation of acephate susceptibility and correlation with esterase and glutathione S-transferase activities in field populations of the tarnished plant bug, Lygus lineolaris

The tarnished plant bug (TPB) has increasingly become an economically important pest of cotton. Heavy dependence on insecticides, particularly organophosphates and pyrethroids, for TPB control facilitated resistance development to multiple classes of insecticides. To better understand resistance and explore ways to monitor resistance in field populations, this study examined acephate susceptibility and the activities of two major detoxification enzymes in nine field populations collected in the Delta region of Mississippi and Arkansas in 2010. Two Arkansas populations from Reed and Backgate had 3.5- and 4.3-fold resistance to acephate, as compared to a susceptible laboratory strain. Extensive planting of cotton and heavy chemical sprays is a major driving force for resistance development to acephate in Mid-south cotton growing areas. Reduced susceptibility to acephate was highly correlated with elevated esterase activities. The acephate-resistant populations from Backgate, Lula, and Reed consistently had higher (up to 5.3-fold) esterase activities than susceptible populations. Regression analysis of LC₅₀s with kinetic esterase activities revealed a significant polynomial quadratic relationship with R² up to 0.89. Glutathione S-transferase (GST) also had elevated activity in most populations, but the variations of GST activities were not significantly correlated with changes of acephate susceptibility. Finally, examination of esterase and GST inhibitors indicated that suppression rates (up to 70%) by two esterase inhibitors in 2010 were slightly lower than those detected in 2006, and ethacrynic acid (EA) inhibited GST effectively in both years. Two other GST inhibitors (sulfobromophthalein and diethyl maleate) displayed significantly lower suppression rates in 2010 than those detected in 2006, suggesting a potential genetic shift in pest populations and a necessity of continued monitoring for insecticide resistance with both bioassay and biochemical approaches. Results indicated that using major detoxification enzyme activities for resistance monitoring may provide insight into acephate resistance in field populations of TPB.     

Possible connection between imidacloprid-induced changes in rice gene transcription profiles and susceptibility to the brown plant hopper Nilaparvatalugens Stål (Hemiptera: Delphacidae)

The chemical pesticide, imidacloprid (IMI) has long-lasting effectiveness against Hemiptera. IMI is commonly used to control the brown planthopper (BPH), Nilaparvata lugens Stål (Hemiptera: Delphacidae). Some chemical pesticides, however, can induce the susceptibility of rice to BPH, which has indirectly led to the resurgence of BPH. The mechanism of the chemical induction of the susceptibility of rice to BPH was not previously understood. Here, a 44 K Agilent Rice Expression Microarray was used to identify changes in gene expression that accompany IMI-induced rice susceptibility to BPH. The results showed that 225 genes were differentially expressed, of which 117 were upregulated, and 108 were downregulated. Gene ontology annotation and pathway analysis revealed that differentially expressed genes were mainly classified into the eight functional groups: oxidation reduction, regulation of cellular process, response to stress, electron carrier activity, metabolic process, transport, signal transducer, and organismal development. The genes encoding plant lipid transfer protein, lignin peroxidase, and flavonol-3-O-methyltransferenase may be important responses to the IMI-induced susceptibility of rice to BPH. The reliability of the microarray data was verified by performing quantitative real-time PCR and the data provide valuable information for further study of the molecular mechanism of IMI-induced susceptibility of rice.     

Goats are susceptible to Bubaline alphaherpesvirus 1 infection: Results of an experimental study

Herpesvirus infections are generally subjected to strong host species restriction, although virological and serological investigations have revealed the possibility of cross-species infections in closely related animal species. In this study we evaluated susceptibility of goats to infection by Bubaline alphaherpesvirus 1 (BuHV-1). Four goats were inoculated intra-nasally with BuHV-1 and monitored clinically, virologically and serologically for 42 days. None of the goats displayed clinical signs although all the animals variably shed the virus by the nasal route during the first 12 days after infection. BuHV-1 was also detected in the white blood cells of two animals in the first week post infection. The results suggest that goats are susceptible to BuHV-1 infection and that they could play an epidemiological role in the circulation/transmission of the virus among domestic and wild ruminants and impact to some extent on the control plans for herpesviruses in cattle.     

大豆灰斑病菌菌丝块离体叶接种快速鉴定方法的建立

[目的]建立一种室内可重复、快速准确鉴定大豆对灰斑病抗性的方法。[方法]利用大豆灰斑病1号和7号生理小种及6种不同抗性的大豆品种为材料,研究并建立了大豆灰斑病抗性的菌丝块接种快速鉴定方法。[结果]在28℃、12h光照与12h黑暗交替的条件下,Minimal培养基生长的菌丝块接种抗感大豆叶片,菌斑面积明显不同,且鉴定结果与已知抗感品种报道的灰斑病抗性一致。[结论]菌丝块离体叶接种鉴定具有不受生育期和环境条件限制、可重复性强的特点,是大豆灰斑病抗性室内鉴定的一种有效方法。     

Antioxidant,ethylene and membrane leakage responses to powdery mildew infection of near-isogenic barley lines with various types of resistance

Leaves of powdery mildew-susceptible barley (Hordeum vulgare cv. Ingrid) and related near-isogenic lines bearing various resistance genes (Mla12, Mlg or mlo5) were inoculated with Blumeria graminis f. sp. hordei race A6. Fungal attack induced several-fold increases in ethylene emission and electrolyte leakage in leaves of susceptible Ingrid beginning 3 days after inoculation. Activities of peroxidase, superoxide dismutase, glutathione S-transferase, ascorbate peroxidase and glutathione reductase enzymes were induced markedly in susceptible leaves 5–7 days after inoculation. Similar, but less pronounced pathogen-induced changes were detected in inoculated leaves of Mla-type resistant plants that show hypersensitive cell death upon inoculation, and, to an even lesser extent, in the Mlg and mlo lines, where no visible symptoms accompanied the incompatible interaction. Glutathione content increased only in susceptible barley 7 days after inoculation. Catalase activity, total ascorbate content and redox state were not influenced by inoculation in any of the genotypes. The activity of dehydroascorbate reductase was significantly reduced 3–5 days after inoculation in the susceptible parental plants and after 5 days in Mla and Mlg lines, while it was stable in the mlo barley. Slightly elevated levels of H₂O₂ were observed in the inoculated resistant plants. In contrast, H₂O₂ content decreased in the susceptible line 7 days after pathogen attack. These data indicate that high levels of antioxidants are involved in the compatible interaction of susceptible barley and powdery mildew by protecting the pathogen from oxidative damage.