Does resource complementarity or prevention of lodging contribute to the increased productivity of rice varietal mixtures in Yunnan,China?

We conducted an experiment in Gejiu, Yunnan Province of China during the wet season of 2002 to examine the importance of resource complementarity and prevention of lodging in the fast-spreading practice of growing rice varietal mixtures in China to suppress rice blast disease and its associated damage. The hybrid rice variety Shanyou 63 and the glutinous or sticky rice variety Huangkenuo were used to study intra- and inter-varietal competition in the rice intercropping system. The experiment was laid out as a randomized complete block design in four replications with pure stands and mixtures of both varieties at different total planting densities and mixing ratios. In half of the pure stand treatments of glutinous rice a metal frame was installed to prevent lodging. The results showed that resource complementarity between the two rice varieties, resulting from niche differentiation, was marginal and did not greatly enhance the productivity of the rice varietal mixtures. In contrast, prevention of lodging of glutinous rice was identified as an important additional advantage of growing these rice varieties in mixture.     

水稻白叶枯病(Xanthom onas campestris pv.oryzae)抗性遗传研究 Ⅲ.两个成株抗性基因X_a-6与X_a-3的等位性分析

研究了两个品种早生爱国3号和辛尼斯对菲律宾水稻白叶枯病菌4个生理小种、日本小种1和我国菌株的成株抗性遗传和抗性基因的等位关系。这两个抗病品种与感病品种沈农1033杂交所得的 F_1、F_2和 B_1F_1群体的成株抗性反应,表明它们均携有一对显性基因。将早生爱国3号同辛尼斯杂交进行直接等位性测定,并将邳早15和蚌珠芒分别与辛     

中国水稻白叶枯病菌系染色体DNA的RFLP谱型的初析

用２个ＤＮＡ探针ｐＪＥＬ１０１和ｐＢＡＳａｖｒＸａ１０对７８个水稻白叶枯病菌系进行ＲＦＬＰ分型，以分析其群体结构和遗传多样性。分别鉴定出１６种ＲＦＬＰ标记带的谱型。以彼此的带位相似率达８５％为界，可分为簇。参试菌系的群体遗传多样性为０．７７（用ｐＪＥＬ１０１），和０．８３ＲＦＬＰ谱型分析表明：我国多数病原型为杂合组群。白叶枯病菌系的分子表现型的变异，远远大于致病型，两个探针都能有效分析我国菌系的群     

用于生物防治水稻纹拮病的抗细菌的筛选

 分别从健康的水稻植株、感染纹枯病植株、根际土壤、秧田水和菌核上分离出能拮抗水稻纹枯病的假单胞菌属(Pseudomonas spp.)和芽胞杆菌属(Bacillus spp.)的细菌菌株，大多数菌株在室内试验中对菌丝生长有抑制作用，有的菌株在温室试验中起抑制病害和对植株有保护作用， 有的(1／49) 具有促进秧苗生长的作用。纹枯病的病斑相对长度与病害发生率密切相关(r²=0.33，P=0.01)， 与抑菌圈大小(r²=0.3)和离体叶片病斑大小(r²=0.12) 无相关，植株干重与病斑相对长度和发病率均无显著相关(r²=0或0.1)。     

华南及菲律宾稻白叶枯病病原菌株致病性比较研究

 用国际鉴别寄主及中国鉴别寄主分别在华南及菲律宾两地,同时多次重复研究、比较、分析两地的稻白叶枯病病原菌株的致病力。用人工剪接法测定明确了中国及菲律宾的病情分级调查记载标准呈显著相关,均能反映华南与菲律宾的病情调查实际结果。对4个菲律宾和5个华南菌群而言,"金南风"及"脱脱普"全感,而"早生爱国3号"和"爪哇14号"则全抗。"黄玉"对华南菌群Ⅰ及Ⅱ抵抗,但对Ⅲ及Ⅳ群与4个菲律宾菌群则全感。"IR8"及"Cas209"对5个华南菌群全感,而"DV85"则全抗。"IR20"及"IR1545-339"抗华南菌群Ⅰ、Ⅱ、Ⅲ及Ⅳ,但感染Ⅴ群。"TN1"及"金刚30"等品种全部感染华南及菲律宾菌群。"IR26"抗华南菌群Ⅰ、Ⅱ、Ⅲ、Ⅳ和菲律宾菌群Ⅰ,但感染华南菌群Ⅴ和菲律宾菌群Ⅱ、Ⅲ、Ⅳ。试验结果指出:华南菌群Ⅲ、Ⅳ的,致病力与菲律宾菌群Ⅰ相仿,而华南菌群Ⅴ则与菲律宾菌群Ⅳ相类似。此外,还研究比较分析了华南菌株与东南亚菲律宾、泰国和印度尼西亚诸国菌株间的致病力的异同情况。     

Development of Chinese Near-isogenic Line of Rice and Their Differentiating Ability of Pathogenic Races of Blast Fungus

The rice( Oryza L. ) variety, Lijiangxintuanheigu(LTH), is a universally susceptible variety. A set of near-isogenic lines (NILs) of rice which has single resistance gene for each line was developed by use of LTH as recurrent parent and Kusabue,Tsuyuake, K1, PiNo. 4, K60 and BL1, which are from Kiyosawa‘s differential varieties(KDV), as donor parents. Differentiating ability of these NILs to Philippine isolates was compared with that of their donor parents, KDV and IRRI‘ s NILs. The results of comparative studies were as follows: (1) Differentiating ability of Chinese NILs to Philippine isolates was much stronger than that of their donor parents and that of KDV. (2) Chinese NILs had similar ability to differentiate races to IRRI‘s NILs or higher differentiating ability than them. But IRRI‘s NILs almost had no differentiating ability to isolates from japonica rice-growing regions. They can not be used to differentiate races of isolates from japonica ricegrowing regions. Whereas, Chinese NILs can be used to differentiate races of isolates from both japonica ricegrowing regions and indica rice-growing regions. It was concluded that the set of Chinese NILs can be used as international differentials.     

Bacterial populations associated with rice seed in the tropical environment

ABSTRACT During the 1995 wet season, harvested rice seed was collected from farmers' fields at different locations in Iloilo, Philippines. Bacterial isolations from crushed seed yielded 428 isolates. The isolates were characterized by BOX-polymerase chain reaction fingerprinting of total genomic DNA and represented 151 fingerprint types (FPT). Most FPTs were found on a single occasion, although matching fingerprints for isolates from different samples also were found. Identifications were made by cellular fatty acid methyl ester analysis and additional use of Biolog GN/GP MicroPlates and API 20E/50CHE systems. The predominant bacteria were Enterobacteriaceae (25%), Bacillus spp. (22%), and Pseu-domonas spp. (14%). Other bacteria regularly present were identified as Xanthomonas spp., Cellulomonas flavigena, and Clavibacter michiganense. Of the total number of isolated bacteria, 4% exhibited in vitro antifungal activity against Rhizoctonia solani or Pyricularia grisea. Two percent of isolates were pathogens identified as Burkholderia glumae and Burkholderia gladioli. Five percent of isolates induced sheath necrosis on only 50 to 90% of inoculated plants and were related to Bacillus pumilus, Paenibacillus spp., Pseudomonas spp., and Pantoea spp.     

水稻品种苗期阶段对白叶枯病的抗性研究

 根据水稻品种各叶期对白叶枯病的抗性表现和强弱程度可分为四类:(1)全期抗病型;(2)全期中抗型;(3)苗感成株抗病型;和(4)全期感病型。可以看出,水稻品种除少数苗感成抗型外,其余三种抗性类型苗期与成株期的抗性反应是一致的。由于中抗、成抗和感病品种各叶期的抗性有随着叶位的升高而抗性增强的趋势,不同抗性品种在苗期阶段抗感对比均较成株期明显。因此,水稻品种对白叶枯病的抗性鉴定采用苗期鉴定方法是可行的。影响水稻品种苗期抗性的因素是:苗龄(叶期)、观察时期、品种与菌株的组合等。     

拮抗细菌菌株Bacillus spp.间的相互作用及其对水稻纹枯病的抑制

测定了6个Bacillus spp.和1个Pseudomonas sp.P-13(G-对照菌株)在PPM培养基上的相互作用。在总共42个组合中，有27个组合是可亲和性的。在以B5423为单剂之一的5个组合中，亲和性的组合有4个。在温室条件下通过分批播种，在水稻分蘖盛期喷以B5423-R(B5423的标记菌株，是利福平抗性的突变体)为单剂之一的4个亲和性组合的菌悬浮液，以检测该组合中B5423-R在水稻茎基部的种群数量。结果发现，与单剂B5423-R相比，在应用1～7天内，组合B5423-R B45中，B5423-R的群体数量显著性降低；组合B5423-R B95、B5423-R B77中，B5423-R的群体数量与单剂无显著差异；组合B5423-R B4313中，B5423-R的群体数量在应用1～4天内与单剂无显著性差异，但在应用第7天显著地高于单剂。离体叶片纹枯病痛斑面积的抑制试验表明，与各自的单剂相比，组合B95 B5423及B95 Er77显著地抑制了纹枯病病斑面积；而组合B45 B80、B45 B5423和B45 B95纹枯病病斑面积显著地高于各自的单剂；其余10个组合与各自的单剂无显著差异。     

Segmental axonopathy of Merino sheep in New Zealand

AIM: To investigate an axonopathy of Merino sheep that caused progressive hindlimb ataxia and slight to moderate paresis, with the purpose of understanding its pathogenesis.

METHODS: Tissues were fixed in buffered paraformaldehyde or paraformaldehyde and glutaraldehyde, processed into wax and epoxy resin, respectively, and examined by light and electron microscopy. Fresh frozen spinal cord and trigeminal nerve roots were subjected to homogenisation, centrifugation and two-dimensional electrophoresis. Selected protein spots were identified using matrix-assisted laser desorption ionisation (MALDI) mass spectrometry.

RESULTS. By light microscopy, there were large pale foamy spheroidal axonal swellings affecting peripheral as well as central axons. By electron microscopy, these were shown to contain many membrane-bound vesicles. The main abnormalities in expressed proteins involved cytoskeletal elements and myosin heavy chain, the latter interpreted as associated with the molecular motor myosin Va.

CONCLUSIONS: The disorder is the same as that described in Merinos in Australia as segmental axonopathy, and believed to have an inherited aetiology. The lesions and protein changes indicate abnormalities of the cytoskeleton, its relationship with the myelin sheath, and myosin Va molecular motor. The consequence appears to be abnormal axonal transport and inability to maintain the integrity of axons and their myelin sheaths.