Development of Chinese near isogenic lines of rice and their differentiating ability of pathogenic races of blast fungus

To use common differential varieties in the world, a set of international differential varieties, including 6 indica and 2 japonica rice varieties, were set up in the middle of 1960s; in 1976, a set of differential varieties composed of 9 japonica varieties with known resistance gene were established;     

Assessment of quantitative resistance of rice cultivars to Xanthomonas campestris pv. Oryzae: a comparison of inoculation methods

Summary Lesion size and lesion number were measured on cultivars of rice inoculated by clipping or spraying with virulent isolates of Xanthomonas campestris pv. oryzae. Mean percentage diseased leaf area (%DLA) gave a similar ranking for the two inoculation methods but differences in lesion size among cultivars were much more evident after clip than after spray inoculation. Correlation between the methods was high (r=0.82^**), but some cultivars responded differently with the two techniques. Cultivars which had low scores following spray inoculation showed low disease progress during the first nine weeks after transplanting into a screen-house experiment. Assessment after clip inoculation measures resistance due to spread of bacteria within the leaf xylem system, an important component of quantitative resistance. Assessment after spray inoculation measures all resistance, including resistance to entrance of bacteria into the leaf. In order to select rice entries with improved quantitative resistance to X. c. oryzae based on both components, a screening based on lesion length after clip inoculation, followed by a test for lesion number after spray inoculation, is advised.     

中国水稻白叶枯病原菌群体的遗传结构

用Rep-PCR和RFLP两种方法分析了143个水稻白叶枯病Xanthomonas oryzae pv.oryzae菌系。这些菌系采集于长江流域,华南,华北和东北的20个省市的96个点。Rap-PCR是利用一些基于细菌的短的重复单位引物(ERIC,BOX和REP)及来自稻白叶枯病原菌的可动重复单位(IS1112和IS1113)引物的DNA扩增特性。在RFLP分析中,以无毒基因家族中的一个成员avrXa10为探针。Rep-PCR分析呈显较高的单元型多样性(H=0.75)。在4个水稻生长地区中,Rep-PCR分析的结果是:华南稻区的遗传多样性最高(H=0.96),随后为长江流域(H=0.93),东北(H=0.77),华北(H=0.69)。根据3个分簇生物统计的共有指纹型,143个菌系被构成3簇。在各簇中都有来自不同水稻产区的菌系,表明菌系的分簇不受地理区域的影响。     

菲律宾吕宋岛和中国浙江省的稻种非致病假单胞杆菌及相关细菌多样性研究

 在1993～1998年间对采自中国浙江省的116批及菲律宾吕宋岛的129批稻种进行了假单胞杆菌及相关细菌多样性研究。分别从浙江省和吕宋岛分离出1200多个和2300多个有关菌株,并对它们进行了细菌学、致病性和数值分类(Biolog)法测定。结果显示,吕宋岛稻种上的荧光细菌数明显高于浙江省。鉴定出16个假单胞杆菌种或型及2个相关种,其中约一半的细菌种尚未有从稻种上分离出来的记录。503个菌株对水稻纹枯病菌、水稻叶鞘腐败病菌及水稻细菌性褐条病菌的拮抗性测定表明,在浙江省约占稻种细菌总数12%的菌对一个或多个水稻病原菌具拮抗性,而在吕宋岛约占17%左右。     

热带及亚热带稻种病原细菌研究(英文)

在过去的５年间对菲律宾吕宋岛（热带）及中国浙江（亚热带）稻区进行了水稻种传细菌病害及病原的调查与研究。从热带的１２９分及亚热带的１１６份水稻样本中分离出３５００多个细菌菌株,经筛选获得２８０个致病菌。     

应用噬菌体法估测水稻叶片组织中白叶枯病菌（Xanthomonas campestris pv. oryzae）数量研究（英文）

 应用噬菌体法估测了水稻叶片中白叶枯病的增殖。试验表明，溶菌斑数同直接皿测稀释菌液存活细菌数之间表现高度相关，辛尼斯接菌后水稻各个叶位不同时期检测到的菌量与其病斑发展趋势一致，认为在目前对白叶枯病菌缺乏选择性培养基的情况下，这一方法是有效和可靠的。     

Comparison of mycoplasma ovipneumoniae isolates using bacterial restriction endonuclease DNA analysis and SDS-PAGE

Sixteen isolates of Mycoplasma ovipneumoniae recovered from the nasal tract or lungs of sheep from different flocks in New Zealand were examined by bacterial restriction endonuclease DNA analysis (BRENDA) using EcoR1 and by sodium dodecyl sulphate-polycrylamide gel electrophoresis (SDS-PAGE). All isolates gave BRENDA patterns which differed entirely from one another. Following 20 serial passages (corresponding to approximately 67 generations) of an isolate, no charge was detected in the BRENDA pattern.

When eight isolates were examined by SDS-PAGE most bands were common but, nevertheless, each isolate was unique in the sense that they differed from one another in one or more bands. The marked heterogeneity of patterns observed when strains of M. ovipneumoniae are compared by BRENDA, together with the stability of such patterns over many generations, will enable this approach to be used to study the epidemiology of individual strains of M. ovipneumoniae with a flock.     

井冈霉素对混剂中拮抗细菌B-5423-R和稻株上土著细菌群体数量的影响

近年来，国内提出了一种实际的生物防治策略，即将生防制剂与杀菌剂混配。已登记的用于防治水稻纹枯病的混配制剂有17种。然而，混配后拮抗细菌的种群动态未见有报道。作者研究井冈霉素对引入稻株上的拮抗细菌Bacillus subtilis 5423（B-5423）及稻株上土著细菌种群动态的影响，旨为生防制剂与杀菌剂的混配提供理论依据。