牛病毒性腹泻病毒生物型转化分子机制的研究进展

从病毒基因与宿主细胞基因的重组、病毒基因的复制与重排、病毒基因的重复复制和序列插入、病毒基因的缺失和点突变几个方面阐述了牛病毒性腹泻病毒（BVDV）由非致细胞病变型（NCP）向致细胞病变型（CP）转化的分子变异机制。总结了前人对NCP型向CP型BVDV转化研究的结果，归纳了5种生物型转化形式，揭示了BVDV具有高变异性。     

Effects of different cucurbit species and temperature on selected life history traits of the ‘B’ biotype ofBemisia tabaci

The development time and survival rate were determined at three constant temperatures for the ‘B’ biotype ofBemisia tabaci on cucumber (Beit Alpha F₁), cantaloupe (Anzer F₁), squash (Sakız F₁), and watermelon (Galactica F₁). The development time for immature stages at 20, 25 and 30±1°C was, respectively, 33.5, 19.3 and 16.8 days on cucumber; 36.5, 20.8 and 19.60 days on cantaloupe; 37.2, 20.1 and 19.8 days on squash; and 38.9, 23.8 and 21.9 days on watermelon. At 20, 25 and 30°C, the respective percentage survival of immature instars was 73.2, 83.2 and 72.9% on cucumber; 72.9, 84.9 and 75.6% on cantaloupe; 52.1, 76.1 and 57.5% on squash; and 37.6, 64.8 and 40.1% on watermelon. http://www.phytoparasitica.org posting May 14, 2006.     

抗褐飞虱生物型Ⅱ水稻品种抗性稳定性研究

1996～2002年调查桂引901、国粳4号抗褐飞虱的结果表明,在桂引901、国粳4号上褐飞虱的虫口密度均显著低于在当地主栽感虫水稻品种上,说明这两个水稻品种抗性稳定;监测褐飞虱生物型在广西南宁的变异动态,结果表明该虫均以生物型Ⅱ为优势种群,孟加拉型所占比率逐年上升,但上升的速度较慢。对该虫生物型的监测结果进一步反映桂引901、国粳4号的抗性稳定性。     

Properties of acetolactate synthase from sulfonylurea-resistant Scirpus juncoides Roxb. var. ohwianus T. Koyama

Properties of acetolactate synthase (EC 4.1.3.18; ALS) from sulfonylurea-resistant (SUR) Scirpus juncoides Roxb. var. ohwianus T. Koyama were studied biochemically and physiologically in comparison with those from sulfonylurea-susceptible weed (SUS). GR₅₀ values for growth inhibition and I₅₀ values for ALS inhibition by imazosulfuron were determined for both SUR and SUS. Imazosulfuron controlled the SUS above 80% at the dosage more than 10 g a.i./ha but did not control the SUR at the even great dosage of 1000 g a.i./ha. The rates required for 50% growth inhibition of the SUR relative to the SUS (R/S ratio) were 271-fold. The I₅₀ value for inhibition of ALS from the SUS was 15 nM, compared to I₅₀ of >3000 nM for inhibition of ALS from the SUR. These results suggest that a resistance may due to an altered ALS that is insensitive to imazosulfuron. The K_m (pyruvate) value of ALS from the SUR was similar to the K_m for ALS from the SUS, suggesting that a mutation resulting in resistance does not change the affinity of the enzyme for pyruvate. The specific activity of the SUR ALS was similar to that of the SUS ALS, which indicates that resistance is not an over-expression of the enzyme. ALS activity from both biotypes was inhibited by isoleucine, valine, and leucine in this order. However, the SUR ALS was less sensitive to inhibition by valine than the SUS ALS.     

Response of multiple seeded cocklebur and other cocklebur types to herbicide treatment

Multiple seeded cocklebur has been found in the last decade in Texas, and described as a biotype of Xanthium strumarium L with up to 25 seeds per bur instead of the usual two. The multiple seeded bur typically produces up to nine seedlings, causing concern that it may be harder to control than normal seeded common cocklebur. The efficacies of a series of fungal and conventional commercial herbicides have been compared in the greenhouse on seedlings of multiple seeded cocklebur from Texas (MSC-TX) and normal common cockleburs from Texas (NCC-TX), Arkansas (NCC-AR), Illinois (NCC-ILL) and two from Mississippi (NCC-MS#1, NCC-MS#2). Three measures of herbicidal activity (reductions in plant height and dry weight, and mortality) were used. The fungal herbicide Alternaria helianthi (Hansf) Tubaki & Nishihara at 1 x 10(5) conidia ml(-1) + 2 g liter(-1) Silwet L-77 with an 8-h dew period was an effective herbicide with all biotypes, as were the commercial chemical herbicides chlorimuron (14.8 g ha(-1)), imazaquin (29.6 g ha(-1)), sodium hydrogen methylarsonate (MSMA; 279.1 g ha(-1)) and imazethapyr (39.5 g ha(-1)). The membrane-disrupting organic arsenical MSMA was effective with all biotypes, whereas commercial chemical herbicides which act by inhibiting branched-chain amino acid synthesis (chlorimuron, imazaquin and imazethapyr) were less effective against normal seeded common cocklebur biotypes with short stature. These studies showed that multiple seeded cocklebur was at least as susceptible to the biological agent A helianthi and to the conventional commercial herbicides studied as were normal seeded cockleburs, suggesting that existing methods should be adequate to control this novel biotype.     

桃蚜体色生物型与寄主关系的研究

从烟草和油菜上采回各自的红色型、绿色型、黄绿色型、褐色型 4种体色生物型 ,再分别接到烟草、油菜和萝卜上 ,连续 1～ 4代观察记载其体色生物型的稳定性。结果表明 ,桃蚜体色生物型的稳定性随寄主不同存在显著差异 ,不同代别其稳定性也有一定的差异 ,在不同体色生物型中 ,以黄绿色生物型最为稳定     

B型烟粉虱若虫龄期和虫数与西葫芦银叶率的关系

通过B型烟粉虱虫龄、虫数和不同西葫芦品种对西葫芦银叶表达影响的研究表明:2头以上的2龄若虫刺吸危害,西葫芦就可以出现银叶症状.在进行试验的6个西葫芦品种中,金玉对B型烟粉虱的危害表现出良好的抗性.     

水稻品种对褐飞虱不同生物型抗性的HPLC分析

借助高效液相色谱检测了对褐飞虱2种生物型具有不同抗性水平的2类水稻品种中的13个次生化合物色谱峰的差异,并运用多元回归分析法,分别建立了水稻品种对褐飞虱2种生物型的抗性级别与这些次生化合物含量之间的回归模型．结果表明,被测的13个组分中,峰1、峰2、峰8、峰12是影响水稻对褐飞虱生物型Ⅱ抗性水平的主要抗原次生化合物;峰3、峰4、峰5、峰9、峰11、峰12则是水稻抗褐飞虱孟加拉型的主要抗原次生化合物．提出了以抗原次生物质为标记的快速分析、鉴定、预测水稻对褐飞虱生物型Ⅱ、孟加拉型抗性水平的新途径．     

马铃薯青枯病菌生化型研究及菌株接种方法的比较

试验测定了我国山东、广东和广西3省的马铃薯青枯病菌生化型,结果表明:被测菌株包含了生化型Ⅰ、Ⅱ、Ⅲ和Ⅳ4种生化型,其中生化型Ⅱ和Ⅲ为优势生化型,均占被测菌株的40%,被测菌株中未测定出生化亚型。同时,比较了通过伤根灌注法和刺茎法这两种方法在番茄幼苗上接种马铃薯青枯病菌的接种效果,结果表明:与刺茎法相比较,伤根灌注法操作简便,幼苗发病快,发病级数高,是理想的青枯病菌接种方法。     

烟粉虱B型及二个非B型种群的SCAR分子标记

用随机引物H16对浙江采集的烟粉虱(Bemisia tabaci)B型和2个非B型种群进行RAPD分子标记，结果表明: B型、非B型ZHJ-1和非B型ZHJ-2 3个种群分别能稳定地扩增出446、390和1317 bp的特异性片段。将3个种群的特异性片段分别克隆和测序，根据测序结果设计3对SCAR引物。通过PCR反应条件的优化，B型、非B 型ZHJ-1和非B型ZHJ-2 3个种群各自的SCAR引物分别能扩增出本种群的特异性条带，其大小依次为439、366和1238 bp，而其它种群与温室白粉虱(Trialeurodes vaporariorum )则无扩增。