葡萄霜霉病菌侵染抗病和感病品种过程的组织学观察

用苯胺蓝染色结合扫描电镜的方法,观察葡萄霜霉病菌(Plasmopara viticola)在葡萄感病品种‘红提’和抗病品种‘北玫’中的侵染过程,发现两品种从接菌到显症的过程基本一致,但孢子囊伸出气孔的时间、伸出孢囊梗气孔比例、孢囊梗数量及孢囊梗分支,‘红提’比‘北玫’多;菌丝在‘北玫’上生长速度慢,后期生长量也较少。‘红提’的潜育期为4 d,而‘北玫’的为5 d,‘红提’和‘北玫’的长菌丝、分支的长菌丝、疏松菌丝体出现的时间也不同。菌丝生长一段时间后,在‘北玫’上停留在疏松菌丝体阶段,而‘红提’96 h时叶片组织内长满致密的菌丝体。两品种在初生菌丝和长菌丝阶段产生吸器的频率差异显著。     

我国马铃薯主产区病毒病发生情况调查

为了解我国马铃薯病毒病发生情况,在马铃薯主产区黑龙江、内蒙古、甘肃、云南等马铃薯田采集了具有典型病毒病症状的样品、疑似样品和随机无症样品,试管苗和原原种为随机样品,共649份。应用DASELISA方法筛查6种马铃薯主要病毒:PVX、PVY、PVS、PLRV、PVM和PVA。结果表明:129份样品为阳性,PVY的检出率最高,为9.86%,PVS次之,为6.47%;试管苗PVS检出最多,为32份,原原种PVX检出最多,为10份,大田样品PVY病毒发生比例最高,为54份;有38份样品是由多种病毒复合侵染造成的,大田PVY+PVS复合侵染率最高,为2.93%,PVS+PVY+PLRV次之,为0.98%,试管苗PVS+PVM复合侵染率最高,为4.85%。通过历年的检测结果比较,试管苗中PVS病毒检出率最高,原原种中PVX和PLRV病毒成为危害最为严重的病害,大田样品中PVY检出率一直居高不下。     

玉米霜霉病的侵染途径及防治措施

系统综述了玉米霜霉病的症状表现、发生规律和防治措施等方面的研究进展.加强进境植物检疫、及时清除病残体和选育高抗的玉米品种是防治玉米霜霉病的重中之重.     

河南省郏县红牛肠道寄生虫感染情况调查

为了解河南省郏县红牛肠道寄生虫感染情况，采用卢戈氏碘液染色法、饱和蔗糖溶液漂浮法和改良抗酸染色法对河南省郏县地区某红牛养殖场及散养红牛的218份新鲜粪便样本进行了检查，结果发现寄生虫总感染率为66.5%，共检出4种肠道寄生虫，其中球虫、圆线虫、鞭虫和绦虫感染率分别为61.5%、2.3%、6.9%和7.8%，混合感染率为11.5%，阳性粪便中虫卵或卵囊感染强度以轻度感染为主。结果表明，河南省郏县红牛肠道寄生虫感染较为普遍，应加强其肠道寄生虫病的防治。     

A role for Toll-like receptor 4 in the host response to the lung infection of Yersinia pseudotuberculosis in mice

Although a Yersinia pseudotuberculosis (Yptb) lung infection model has been developed to study Y. pestis pathogenesis, it is still necessary to establish a new animal model to mimic the pathophysiological features induced by Y. pestis infection. Here, we provide a new lung infection model using the Yptb strain, IP2777, which displayed rapid spread of bacteria to the liver, spleen, and blood. In addition, we examined whether TLR4 is involved in Yptb-induced pathogenesis in the lung infection model of mice we generated. Following lung infection of WT and TLR4-deficient mice with the Yptb strain IP2777, the survival rate, bacterial colonization, histopathology, and level of cytokines and chemokines in the lung, spleen, liver, and blood were analyzed. TLR4-deficient mice had a lower survival rate than WT mice in response to Yptb lung infection. Although the bacterial colonization and pathology of the lung were comparable between WT and TLR4-deficient mice, those of the spleen and liver were more severe in TLR4-deficient mice. In addition, the levels of TNF-α and CXCL2 in the liver and IL-6 and CXCL2 in the blood were higher in TLR4-deficient mice than in WT mice. Our results demonstrate that TLR4 is necessary for optimal host protection against Yptb lung infection and TLR4-deficient mice may serve as a better genetic model of Yptb infection for mimicking Y. pestis infection.     

影响粉碎机工作性能因素的分析

锤片式粉碎机是一种利用高速旋转的锤片来击碎饲料的机器。它具有通用性广,对饲料的温度敏感性小,调节粉碎方便,粉碎质量好,使用维修方便和生产率高等优点。但是,由于用户对影响饲料粉碎机的工作性能的主要因素分析掌握不够,致使生产率不高、消耗的动力较大,产品质量等指标无法保证。为此,列举了影响粉碎机工作性能的诸因素,为广大用户高效、优质、低耗、安全地使用粉碎机提供了理论基础。     

Control of preharvest aflatoxin contamination in maize by pyramiding QTL involved in resistance to ear-feeding insects and invasion by Aspergillus spp.

Several resistance sources and resistance mechanisms to aflatoxin formation and corn earworm (Helicoverpa zea Boddie) damage to maize (Zea mays L.) have been identified. Based on this knowledge, experiments were initiated toward achievement of the following objectives: (1) to confirm earlier determinations on resistance traits of germplasm sources and to identify quantitative trait loci (QTL) associated with each of the traits, and (2) upon estimation of the degree of QTL effects on each trait, to generate a maize population, with chemical and physical resistance to Aspergillus spp. and ear-feeding insects, for inbred development. A 2-year field experiment to evaluate selected genotypes inoculated with A. flavus and infested with corn earworm revealed that significant variation exists among the genotypes for aflatoxin contamination and corn earworm damage. The protection of maize ears against aflatoxin contamination was primarily dependent on resistance to fungal infection and ear-feeding insects, and excellent husk coverage and tightness. A major QTL (p1) identified on chromosome 1S had effects of 54.0, 42.1, and 28.3% on the phenotypic variability for concentrations of silk maysin, 3′-methoxymaysin+apimaysin, and chlorogenic acid, respectively. Markers/QTLs for husk phenotypic traits and total aflatoxin concentrations have been determined, but more detailed mapping of these chromosomic regions will be necessary to locate precise markers/QTLs for husk traits and aflatoxin production. Realizing the complexity of the Aspergillus–aflatoxin-maize system and the factors affecting aflatoxin contamination, we are directing our program toward marker-assisted breeding to enhance or improve general genetic resistance to ear-feeding insects and invasion by Aspergillus spp.     

Influence of race and post infection temperature on two components of partial resistance to wheat leaf rust in seedlings of wheat

Summary Components of partial resistance, infection frequency and latency period, were determined in 71 winter and spring wheat genotypes in the seedling stage, after infection with three races of leaf rust (Felix 3B, Clement B and Betuwe 85C) at three different day/night temperature regimes (24/18°C, 18/12°C and 12/6°C). The genotypes were split into two groups and two separate experiments were carried out. Five genotypes, SVP 84039, Akabozu, Banco, BH 1146 and Orso, conferred a low infection frequency and a long latency period and Westphal 12A a long latency period, indicating a relatively high level of partial resistance. The correlation coefficient between infection frequency and latency period was low. Race-specificity was not found. There was a significant temperature effect on the latency period. In the second experiment the temperature x genotype interaction was significant. Temperature-response functions of transformed data demonstrated that the latency periods of four relatively resistant genotypes, Westphal 12A, Banco, BH 1146 and Orso and of Sarno and Mirela were most sensitive to temperature. The range between the genotypes with the longest and the shortest latency period was highest at 12°C. Therefore, low temperature regimes are preferred to distinguish differences in level of partial resistance.     

Variation of grain iron content in a local upland rice germplasm from the village of Huai Tee Cha in northern Thailand

Crown rust caused by Puccinia coronata Cda. f. sp. avenae Eriks., is a major fungal disease of cultivated oats (Avena sativa L.) in Tunisia. Six landrace oats (M_tK₂, JT₅, BJ₃₅, GT₁, ZN₃ and JT₀) locally collected and previously screened for their relative oat crown rust resistance were used in this experiment. These accessions were evaluated during a two cropping season in field plots under heavy natural oat crown rust infection. Assessment criteria to crown rust reactions were AUDPC, latent period, uredinia size and number of uredinia per cm² of infected leaf area. Principal components analysis showed that the variables were grouped in two components. These two principal components explained 83.56% of the total variance. The projection of the point-cloud representing the populations on the plan formed by the principal components ‘Fact 1’ (63.83%), in abscissa, and ‘Fact 2’ (19.73%) in ordinate, permitted to distribute the accessions in several groups. Three landrace oats (M_tK₂, JT₅, and JT₀) showed the lowest value of all the components used. These landrace oats might be good sources of effective and durable resistance to crown rust.     

Optimal allocation of resources in evaluating current sunflower inbred lines for resistance to Sclerotinia

Sclerotinia sclerotiorum (Lib.) de Bary is a major limiting factor for sunflower (Helianthus annuus) production. This study was conducted to (1) evaluate a large number of current sunflower lines for their reaction to Sclerotinia, and (2) determine the optimum allocation of resources for their selection. A set of 85 inbred lines was screened under artificial leaf infection in three environments. The test revealed ample variation for all resistance traits in the current germplasm. A line selected from NDBLOS, an oilseed sunflower germplasm poo, and its derivatives were most resistant to Sclerotinia. Lines derived from interspecific crosses with the wild species Helianthus tuberosus and Helianthus argophyllus also showed satisfactory Sclerotinia resistance. The evaluation of five plants per plot in two replications and four environments appears to be a reasonable allocation of resources in order to optimize the selection response.