Resistance of wheat to Fusarium spp. in an in vitro seed germination assay and preliminary investigations into the relationship with Fusarium head blight resistance

Resistance of wheat cultivars from the UK, 2003 recommended list were evaluated against Fusarium culmorum, F. graminearum, Microdochium nivale var. majus and var. nivale, F. avenaceum and F. poae using a seed germination assay and related to previously published data on detached leaf assays, using M. nivale, and UK recommended list Fusarium head blight (FHB) resistance ratings. Significant cultivar differences were found after inoculation with all fungal species with the exception of F. poae where the decline in the percentage of seed germinating relative to the controls was small. Correlations of the percentage seed germinating inoculated with the remaining Fusarium spp. and M. nivale were high (r = 0.68; P < 0.01 to r = 0.94; P < 0.001). Overall, F. graminearum caused the greatest reduction with a mean seed germination of 61.7% relative to the controls followed by F. avenaceum (65.5%), M. nivale var. majus (67.2%), F. culmorum (76.6%), M. nivale var. nivale (89.2%) and was least for F. poae (92.5%). The resistance detected in the germination assay was significantly correlated to whole plant FHB resistance ratings (r_s = 0.45; P < 0.05) but was not correlated to partial disease resistance (PDR) components detected using the detached leaf assay, namely, incubation period, latent period and lesion length. The results suggest that while resistances detected in the seed germination and detached leaf assays may in part share a common genetic basis to FHB resistance, resistances detected in both in vitro assays are independent of each other. Resistances detected in the seed germination assay had a lower correlation with FHB resistance ratings against F. culmorum, than those detected by latent period in the detached leaf assay.     

Gamma Ray-Induced Field Tolerance to Phytophthora Blight in Sesame

Due to the non-availability of sources of resistance in Sri Lanka to Phytopbthora blight in sesame (Sesamum indicum) caused by Phytopbthora nicotianae var. parasitica, a mutation breeding programme was initiated. Seeds of three genotypes were subjected to six doses of gamma rays from 100 Gy to 750 Gy from a ⁶⁰Co source. Seeds of M₂ bulks, sampled by variety and treatment from the first five capsules formed on M₁ plants, were grown in a field with a history of repeated incidence of the disease. The best 21 lines, having the highest survival and seed production, identified in the screening of M₃ and M₄ progeny rows of selected M₂ single plants were then tested in a replicated field trial with the recommended cultivar ‘MI 3’ as a control. The plant survival in selected lines averaged 43.3 percent as against 7.2 percent in the recommended variety. Eight selections recorded significantly higher seed yield than ‘MI 3’ at P < 0.01 and another three at P < 0.05. Gamma ray treatments of 450 Gy and 600 Gy produced more lines tolerant to the disease than the other doses used.     

Shading of plants facilitates selection for powdery mildew resistance in Squash

Summary Powdery mildew development was assessed on squash (Cucurbita pepo) plants of a susceptible cultivar, a resistant accession, their F₁, and their F₂ in an early summer planting in the field, covered or not covered with a shading net. Three reaction types were observed: susceptible, powdery mildew on stems and on both, the upper and lower leaf surfaces, as in the susceptible parent; resistant, no powdery mildew on leaves or stems, as in the resistant parent; and partially resistant, powdery mildew on upper leaf surfaces only, as in the F₁. Disease presence on the stem was associated with susceptibility. Shading hastened the appearance of powdery mildew and increased the severity of infection on partially resistant and susceptible plants, facilitating identification of resistant individuals in the F₂ population.Contribution No. 1613-E from the Agricultural Research Organization, Bet Dagan, Israel     

Interspecific hybrids of Cyclamen persicum and C. graecum

Summary Interspecific crosses were made to introduce the disease resistance of Cyclamen graecum into C. persicum cultivars and the abortive hybrid embryos were rescued by ovule culture. Diploid and tetraploid cultivars of C. persicum (CPD, 2n=2x=48; CPT, 2n=4x=96) were the pistillate parents and wild form of C. graecum (CG, 2n=84) were the staminate parents. After pollination, crossed ovaries were periodically collected and examined using paraffin sections. Histological observations suggested that both hybrid ovules of CPD × CG and CPT × CG should be transferred to the culture medium 35 days after pollination. Based upon this observation, crossed ovaries were collected 35 days after pollination, then ovules with placenta were explanted on culture medium and cultured in the dark at 25°C. Plantlets were induced from ovules cultured in MS medium containing 3% sucrose and 10% coconut milk. The hybrids (2n=66) derived from CPD × CG failed to yield viable seeds by self-pollination, although they showed some pollen fertility. In contrast, the hybrids (2n=90) derived from CPT × CG showed high pollen fertility and yielded viable seeds by self-pollination. Furthermore, they were resistant to disease caused by Fusarium oxysporum f. sp. cyclaminis, Erwinia herbicola pv. cyclamenae and Pseudomonas marginalis pv. marginalis.Abbreviations CPD C. persicum diploid - CPT C. persicum tetraploid - CG C. graecum     

Genetics of resistance to ascochyta blight in chickpea (Cicer arietinum L.)

Summary Six chickpea lines resistant to Ascochyta rabiei (Pass.) Lab. were crossed to four susceptible cultivars. The hybrids were resistant in all the crosses except the crosses where resistant line BRG 8 was involved. Segregation pattern for diseases reaction in F₂, BCP₁, BCP₂ and F₃ generations in field and glasshouse conditions revealed that resistance to Ascochyta blight is under the control of a single dominant gene in EC 26446, PG 82-1, P 919, P 1252-1 and NEC 2451 while a recessive gene is responsible in BRG 8. Allelic tests indicated the presence of three independently segregating genes for resistance; one dominant gene in P 1215-1 and one in EC 26446 and PG 82-1, and a recessive one in BRG 8.Research paper No. 3600     

基于网络的鸡病防治与诊断专家系统的设计

目前中国鸡病防治中存在一些暂时无法解决的难题,如基层中鸡病诊断专家缺乏、鸡病防控不及时等。基于现状,利用计算机网络技术和人工智能技术,将SQL数据库和ASP.NET技术相结合,设计并开发了基于网络的鸡病防治与诊断专家系统。该系统将鸡病诊断和鸡病防治知识进行集成,采用基于规则的模糊化的混合推理策略,实现了鸡病诊断和防治的数字化和智能化,用户可通过网络实现鸡病诊断、鸡病防治、鸡群管理、知识查询和统计分析等功能。经验证性试验和专家评测,该系统结构合理,功能完善,可以满足广大基层用户的需求,具有一定的推广应用前景。     

甜瓜新品系的选育及可用性评价

利用网纹甜瓜和哈密瓜类型材料杂交，经6－7代系谱选择，选育出了3个网纹甜瓜新品系，并对其稳定性、抗病性和配合力进行了综合评价。结果表明：品系1、品系2表现出高度的一致性和遗传稳定性；品系1对白粉病呈HR抗性，品系2呈R抗性，品系3呈MR抗性；品系1和品系3单果重的一般配 力效应呈正向效应（GCA值分别为0．02和0．09），品系2的网纹一般配合力高（GCA值为0．16），品系3的单果重、果肉厚、糖含量均呈正向效应。     

患出血病鲫鱼主要组织可溶性蛋白质变化的研究

采用SDS-聚丙烯酰胺凝胶电泳法(SDS-PAGE)对正常和患出血病的鲫鱼心、肝、肾、鳃、脑、肌肉、肠、眼8种组织中可溶性蛋白质进行比较分析。结果表明：病鱼的心、肝、肾、鳃、脑、肌肉6种组织的蛋白质电泳谱带与正常鱼相比有较大变化，心和肾各缺失5条谱带；肝新诱导出1条谱带，另有1条谱带缺失；鳃中新诱导出2条谱带，有2条谱带缺失；脑中增加了4条新谱带，1条谱带缺失；肌肉新增5条谱带。说明鱼在遭受病原菌侵袭后，蛋白质的合成代谢受到较大影响。这些变化可作为辅助疾病诊断的生化指标。     

抗病优质大白菜“秋白70”的选育

优质、抗病的大白菜新品种——秋白70是利用天津青麻叶为母体，进行游离小孢子培养，并结合人工接种鉴定技术于2002年育成功。该品种长势旺，成熟期70d，株型较直立，株高48cm，开展度51cm，外叶8片，叶形长倒卵形，叶色深绿，叶面多皱，绿帮；叶球长筒形，颜色绿，叶球内叶颜色浅黄，心叶拧抱，舒心；叶球高44cm，直径14cm，单球重2.2kg左右，净菜率82.3%。品质优良，口味佳。较抗霜霉病和病毒病。平均产量10.8kg/m2。     

FMDV OA/58病毒株VP1蛋白结构构建与B细胞抗原表位的预测

以口蹄疫病毒株OA/58 RNA为模板,反转录并扩增目的cDNA,然后与pGEM-T easy载体连接并转化JM109菌株,提取的重组质粒用凝胶电泳、PCR和EcoR Ⅰ酶切法鉴定.运用同源模建得到OA/58 VP1蛋白3D结构,并结合理化性质、亲水性、可塑性和免疫原性进行分析,预测OA/58 VP1的抗原表位.结果 OA/58 VP1存在多个潜在的抗原表位位点,可能的蛋白质抗原表位区域:2～11,15～35,38～50,77～88,90～107,121～125,131～135,140～149,154～163,169～175,178～189,197～213.应用同源模建得到的OA/58 VP1蛋白3D模型来预测其B细胞表位,为进一步研究OA/58 VP1功能,构建突变体和选择表达新型OA/58 VP1蛋白分子提供有参考价值的信息.