Bacterial diseases of potatoes: from classical phytobacteriology to molecular pathogenicity

Various bacterial pathogens attack potato plants and tubers. These pathogens includeErwinia, Corynebacterium (Clavibacter), Psuedomonas andStreptomyces. Over the past few years there have been significant advances in the molecular biological analysis of several of these pathogens and this is now helping us to understand the major aspects of virulence mechanisms. However, to date, such information is not sufficiently useful to allow us to intervene rationally in these potato diseases, except by the standard practises of good husbandry.     

ONCHOCERCA GUTTUROSA IN Danish cattle. Prevalence, geographic distribution and host-vector relationships.

1. Onchocerca gutturosa is reported in Danish cattle for the first time. Microfilariae were found in 38 (9.4%) of 406 cows that were 2 years or older.
2. Microfilariae were not randomly distributed throughout the skin but were concentrated in the umbilical area.
3. No difference in prevalence was observed between breeds of cattle.
4. Most of the infected cows had grazed on fields close to streams that contained Simulium ornatum, the vector of O. gutturosa.
5. Differences in preferred biting sites of S. ornatum from cow to cow were correlated with the arrangement of hair.

     

Approach of allelopathy study with Arabidopsis thaliana (L.) Hevnh. and Neurospora crassa

Allelopathy in Arabidopsis seeds was investigated in the present study because there are few available reports of allelopathy studies regarding the early development stage of the plant life cycle, and because Arabidopsis is widely used as a model plant for molecular biology. When cockscomb ( Celosia cristata ) was incubated together with Arabidopsis seeds, the growth of cockscomb was promoted by Arabidopsis seeds. Exudate of Arabidopsis seeds showed a promotive activity on the growth of cockscomb and Arabidopsis itself. A new method for studying allelopathic mechanisms involving the interaction of the plant Arabidopsis thaliana (L.) Hevnh. and the fungus Neurospora crassa was suggested. Arabidopsis seed exudate and the water-soluble fraction of the exudate promoted Arabidopsis growth and reduced fungal germination, indicating that the seed exudate has a species-selective activity. Conversely, the ethylacetate-soluble fraction inhibited growth of all tested materials in the current study. These results demonstrate that the water-soluble substance(s) released from Arabidopsis seeds have species-selective activity on growth of both plants and microorganisms.     

外源绿原酸对苹果抗病相关酶的影响

采用离体培养方法对富士、红星和八棱海棠进行绿原酸处理,研究苹果在外源绿原酸处理下POD、PPO、PAL活性的动态变化以及绿原酸含量的变化。结果表明,富士以0.0001%绿原酸、红星以0.0008%绿原酸、八棱海棠以0.0004%绿原酸处理后,其PAL活性均显著提高,苹果体内也因此而提高了绿原酸水平。     

干椒新品种蓉椒6号的选育

自交系9804和9909杂交配制成杂交一代干椒，植株生长旺盛，座果力强，较抗病毒病和疫病，果实指形，纵长17～19cm，横径1．2cm，青熟果绿色，老熟果鲜红色，单果重8．3g，味辣，品质佳，中熟品种，从定植到采收55d(天)，一般每667m^2产1500～1900kg。     

15%苯乙锡·井可湿性粉剂防治稻曲病和稻瘟病试验与研究

近几年来,稻曲病和稻瘟病有流行加剧趋势,长期使用稻瘟灵、三环唑等常规药剂防治药效有所下降。江苏金凤凰农化有限公司研制的15%苯乙锡·井可湿性粉剂(瘟曲必克)经试验能有效地控制穗期稻曲病和稻瘟病的危害。     

Identification,Characteristics and Function of Phosphoglucomutase (PGM) in the Agar Biosynthesis and Carbon Flux in the Agarophyte Gracilariopsis lemaneiformis (Rhodophyta)

Agar is widely applied across the food, pharmaceutical and biotechnology industries, owing to its various bioactive functions. To better understand the agar biosynthesis in commercial seaweed Gracilariopsis lemaneiformis, the activities of four enzymes participating in the agar biosynthesis were detected, and phosphoglucomutase (PGM) was confirmed as highly correlated with agar accumulation. Three genes of PGM (GlPGM1, GlPGM2 and GlPGM3) were identified from the G. lemaneiformis genome. The subcellular localization analysis validated that GlPGM1 was located in the chloroplast and GlPGM3 was not significantly distributed in the organelles. Both the GlPGM1 and GlPGM3 protein levels showed a remarkable consistency with the agar variations, and GlPGM3 may participate in the carbon flux between (iso)floridoside, floridean starch and agar synthesis. After treatment with the PGM inhibitor, the agar and floridean starch contents and the activities of floridean starch synthase were significantly decreased; products identified in the Calvin cycle, the pentose phosphate pathway, the Embden-Meyerhof-Parnas pathway and the tricarboxylic acid cycle were depressed; however, lipids, phenolic acids and the intermediate metabolites, fructose-1,6-phosphate were upregulated. These findings reveal the essential role of PGM in regulating the carbon flux between agar and other carbohydrates in G. lemaneiformis, providing a guide for the artificial regulation of agar accumulation.     

用免疫分离法检测稻种上的白叶枯病菌

 免疫分离法是一种新型的、高度灵敏和准确的种菌带菌检验法,它结合了利用专化性抗血清的选择法吸附作用和活细菌可形成菌落的两方面的优点,从种苗材料中分离到目标细菌,用纯菌测试它的回收率为50~70%,最低检出率为50~100个菌/ml,人工喷接种和病田收获的病种带菌率达87%,平均每粒自然病种上的细菌数在100个左右。免疫分离所得菌落经致病性测定,大多数为白叶枯菌。     

狭叶菖蒲乙醇提取物对棉铃虫卵和幼虫的生物活性

为筛选安全高效的棉铃虫防治药剂,选用狭叶菖蒲Acorus calamus var.angustatus乙醇提取物对棉铃虫Helicoverpa armigera卵和幼虫的触杀活性、胃毒作用、拒食效果和生长抑制作用进行了测定,同时以0.5%藜芦碱为药剂对照,对比分析狭叶菖蒲提取物的杀虫效果。结果表明,狭叶菖蒲乙醇提取物对棉铃虫3龄幼虫有显著的触杀、胃毒、拒食和生长抑制活性以及杀卵效果,且生物活性随浓度升高和处理时间延长而增加;狭叶菖蒲提取物对棉铃虫触杀活性、胃毒活性、杀卵活性的致死中浓度LC_(50)分别为20.50、19.26和31.39 mg/m L,对棉铃虫生长抑制中浓度EC_(50)和拒食中浓度AFC_(50)分别为7.15、10.43 mg/m L;0.5%藜芦碱药剂对棉铃虫触杀活性、胃毒活性和杀卵活性LC_(50)分别为12.19、16.90和29.87 mg/m L,对棉铃虫EC_(50)和AFC_(50)分别为3.99、8.32 mg/m L,均低于菖蒲根茎提取物。气相色谱-质谱分析结果显示,狭叶菖蒲乙醇提取物主要成分为α-细辛醚、β-细辛醚、菖蒲酮和白千层醇。表明狭叶菖蒲乙醇提取物有开发为新型植物源农药的潜力。