分子标记辅助选育抗稻白叶枯病的低温敏核不育系3178S

本研究以IRBB21为Xa21基因供体，籼型低温敏不育系399S为低温核不育系基因供体，采用杂交和回交方法，逐代用分子标记检测手段，导入广谱抗白叶枯病基因Xa21和低温敏核不育系基因，聚合双亲的有利性状，育成抗白叶枯病的籼型低温敏核不育系3178S，其抗性达到了IRBB21的抗性水平，且保持了399S稳定的育性和双亲的优良经济性状。     

云南3种野生稻中抗白叶枯病基因的鉴定

白叶枯病是水稻生产上最重要的细菌性病害之一,培育抗病新品种是防治白叶枯病最经济有效的途径。然而,栽培稻来源的抗病基因数量有限,并且部分抗病基因的抗病谱窄。因此,从野生稻中发掘抗病基因,将有利于培育抗病谱广且抗病能力强的水稻新品种。本研究通过抗性鉴定和PCR分析,检测云南野生稻中的抗白叶枯病基因。结果表明,云南野生稻对2个代表性白叶枯病菌Y8和PXO99具有不同程度的抗性,疣粒野生稻甚至达到免疫的程度。功能标记检测结果显示,3种野生稻中均不含xa5、xa13和Xa21抗病基因,元江普通野生稻含Xa23和Xa3/Xa26基因或其同源基因,景洪普通野生稻中含Xa1、Xa3/Xa26和Xa27基因或同源基因,药用野生稻含Xa3/Xa26基因或同源基因,而疣粒野生稻含有Xa27抗性基因。本研究结果为进一步发掘和克隆云南野生稻中的抗白叶枯病新基因提供了理论参考。     

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     

胁迫相关蛋白激酶基因OsSAPK2调控水稻抗白叶枯病反应

水稻蔗糖非酵解型蛋白激酶Sn RK2,又称胁迫相关蛋白激酶(stress-activated protein kinase genes in rice,Os SAPKs),在调控水稻非生物胁迫信号传导中起着重要作用。本研究对Os SAPK2的结构及其在水稻抗白叶枯病反应中的功能进行了初步研究。结果表明Os SAPK2被定位于细胞核和细胞质内,与Os SAPK1、Os SAPK3同属于Kulik’s II组。Os SAPK2-RNAi转基因水稻中Os SAPK2下调表达,人工接种水稻白叶枯病菌后,转基因水稻比受体对照的病斑长度显著增长,抗病相关基因Os LRR1、Os HIR1表达水平下降,感病相关基因Os MAPK5表达水平升高。此外,Os SAPK2具有自激活活性,可能与Os MAPK5等胁迫相关蛋白互作。上述结果为进一步研究Os SAPK2调控水稻抗白叶枯病的分子机制提供了信息。     

不同Xa21转基因杂交稻组合的大田试验与分析

在北京、四川和江苏等地对Xa21转基因杂交稻进行了大田释放实验. 分别对转基因纯合的3个恢复系明恢63-Xa21、盐恢559-Xa21和C418-Xa21与各种不育系配组的23个杂交组合进行了抗性和农艺性状分析. 在不同的杂合遗传背景下转基因Xa21稳定遗传和高效表达, 所有杂交组合均具有对白叶枯病的广谱抗性. 转基因恢复系配制的杂交组合与     

Long-term impact of fertilization on activity and composition of bacterial communities and metabolic guilds in agricultural soil

To explore long-term impact of organic and inorganic fertilizers on microbial communities, we targeted both the total bacterial community and the autotrophic ammonia oxidizing bacteria (AOB) in soil from six treatments at an experimental field site established in 1956: cattle manure, sewage sludge, Ca(NO₃)₂, (NH₄)₂SO₄, unfertilized and unfertilized without crops. All plots, except the bare fallows, were cropped with maize. Effects on activity were assessed by measuring the basal respiration and substrate induced respiration (SIR) rates, and the potential activity of the AOB. To determine the bacterial community composition, 16S rRNA genes were used to fingerprint total soil communities by terminal restriction fragment length polymorphism analysis and AOB communities by denaturing gradient gel electrophoresis. The fertilization regimes had clear effects on both activity and composition of the soil communities. Basal respiration and r, which was kinetically derived as the exponentially growing fraction of the SIR-response, correlated well with the soil organic C content (r=0.93 and 0.66, respectively). Soil pH ranged from 3.97 to 6.26 in the treatments and was found to be an important factor influencing all microbial activities. pH correlated negatively with the ratio between basal respiration and SIR (r=0.90), indicating a decreased efficiency of heterotrophic microorganisms to convert organic carbon into microbial biomass in the most acid soils with pH 3.97 and 4.68 ((NH₄)₂SO₄ and sewage sludge fertilized plots, respectively). The lowest SIR and ammonia oxidation rates were also found in these treatments. In addition, these treatments exhibited individually different community fingerprints, showing that pH affected the composition of AOB and total bacterial communities. The manure fertilized plots harbored the most diverse AOB community and the pattern was linked to a high potential ammonia oxidation activity. Thus, the AOB community composition appeared to be more strongly linked to the activity than the total bacterial communities were, likely explained by physiological differences in the populations present.     

DGGE fingerprinting of culturable soil bacterial communities complements culture-independent analyses

Culture-dependent DGGE (CD DGGE) fingerprinting of the 16S rRNA gene was used to characterize mixed bacterial communities recovered on agar plates. Using R2A Agar as a growth medium, CD DGGE analysis resulted in clear banding patterns of sufficient complexity (16-32 major bands) and reproducibility to investigate differences in bacterial communities in a silt loam soil. Replicate CD DGGE profiles from plates inoculated with less-dilute samples (10⁻³) had a higher band count and were more similar (72-77%) than profiles from more-dilute samples (51-61%). Different culture media and incubation conditions resulted in distinct community fingerprints and increased the cumulative number of unique bands detected. When CD DGGE fingerprints were compared to profiles constructed from 16S rRNA genes obtained from culture-independent clone libraries (CB DGGE profiles) 34% of the bands were unique to the culture-dependent profiles, 32% were unique to the culture-independent profiles and 34% were found in both communities. These data demonstrate that culture-independent DGGE profiles are supplemented by the distinct bands detected in culture-dependent profiles. CD DGGE can be a useful technique to follow the dynamics of distinct culturable fractions of the soil bacterial community.     

Infection and colonization of aseptically micropropagated sugarcane seedlings by nitrogen-fixing endophytic bacterium, Herbaspirillum sp. B501gfp1

In this study, we used Herbaspirillum sp. B501gfp1 (B501gfp1), an isolate from wild rice, to investigate the interaction between a non-host nitrogen-fixing endophytic bacterium and micropropagated sugarcane plants under aseptic condition. Two Japanese sugarcane plants (Saccharum sp.) cultivars (cvs) NiF8 and Ni15 were inoculated using B501gfp1 in two inoculum doses of 10⁸ and 10² bacterial-cells-per-milliliter suspension. The results showed that bacterial cells colonized both the root and stem tissues, and colonization was apparent in the intercellular spaces. Higher bacterial numbers were detected in plant tissues inoculated with the higher inoculum concentration treatment. Bacterial numbers also varied between the two cultivars, with the higher values determined in cv Ni15. This study provides evidence that Herbaspirillum sp. B501gfp1, a rice isolate, could colonize sugarcane tissues, suggesting non-specificity of host plant among endophytes.     

云南稻种对白叶枯病菌系抗性分析

 从1983～1990年,用云南主要的4个菌系群菌株,测定了28个单位的940份地方水稻品种抗性,结果表明抗1群菌的材料占30.0%,抗Ⅱ群菌占29.3%,抗Ⅲ群菌占30.3%,抗Ⅳ群菌占28.2%。通过比较分析,筛选了部分品种供生产和推广使用,研究证明菌系与品种有特异性交又互作关系。