玉米抗病基因一致性图谱的构建

发掘和精细定位玉米抗病基因是构建玉米抗病分子育种技术体系的重要基础。利用生物信息学手段,整理文献和玉米基因组数据库中已有的抗病基因定位的信息,借助高密度玉米分子标记连锁图谱IBM22005neighbors,通过染色体映射的方法,绘制了玉米抗病基因的一致性图谱。结果显示,在试验涉及到的14种主要玉米病害的78个抗病主基因或QTL之中,抗病基因在各条染色体上呈不均匀分布,第3、第6、第10染色体上的主效抗病基因较多,第5和第7染色体上的抗病基因较少,且抗病基因呈簇集分布。研究结果为进一步发掘和鉴定玉米抗病基因和建立玉米抗病分子标记辅助育种技术体系奠定了基础。     

AcrAB Efflux Pump in Fluoroquinolone Resistant Salmonella gallinarum Induced by Ciprofloxacin Selective Pressure

Salmonella gallinarum has shown multiple drug resistance (MDR),especially high level fluoroquinolone (FQ) resistance in recent years.To determine whether the active efflux system was responsible for high-level FQ resistance,this research studied AcrAB efflux pump in Salmonella gallinarum on molecular level.The resistant strains were induced by standard strain C79-13 with ciprofloxacin in vitro.With carbonylcyanide-p-chlorophenyl hydrazone (CCCP) as an energy inhibitor,efflux inhibition test initially showed the potential impact of efflux pump on drug resistance.Sequence analysis of acrA gene indicated that gene mutation of AcrAB efflux pump was not definitely associated with MDR and drug resistance level of Salmonella gallinarum.Detected by competitive RT-PCR,the mRNA expression of acrA and acrB genes in the resistant strains significantly increased (p0.01) compared with that of the control strain C79-13.The mRNA expression level of acrB gene (increased from 1.6-to 2.9-folds) was consistent with that of acrA gene (increased from 1.6-to 2.8-folds),which increased with the drug resistance level.However,gene mutation of acrA gene showed no correlation with its mRNA expression level,indicating that gene mutation did not affect the expression of AcrAB pump itself.The results suggested that the overexpression rather than the gene mutation of AcrAB efflux pump was an important factor causing the high level drug resistance of Salmonella gallinarum.     

Reversal of chloroquine resistance in malaria parasite Plasmodium falciparum by desipramine

Desipramine and several other tricyclic antidepressant drugs reverse chloroquine resistance in Plasmodium falciparum in vitro at concentrations observed in the plasma of human patients treated for depression. Reversal of resistance is associated with increased chloroquine accumulation in the parasite, probably because of inhibition of a putative chloroquine efflux pump. When owl monkeys (Aotus lemurinus lemurinus) infected with chloroquine-resistant Plasmodium falciparum were treated with chloroquine plus desipramine, their parasitemias were rapidly suppressed. Desipramine was found to be one of the most effective compounds yet described for the reversal of chloroquine resistance both in vitro and in vivo.     

Mutational inactivation of STAG2 causes aneuploidy in human cancer

Most cancer cells are characterized by aneuploidy, an abnormal number of chromosomes. We have identified a clue to the mechanistic origins of aneuploidy through integrative genomic analyses of human tumors. A diverse range of tumor types were found to harbor deletions or inactivating mutations of STAG2, a gene encoding a subunit of the cohesin complex, which regulates the separation of sister chromatids during cell division. Because STAG2 is on the X chromosome, its inactivation requires only a single mutational event. Studying a near-diploid human cell line with a stable karyotype, we found that targeted inactivation of STAG2 led to chromatid cohesion defects and aneuploidy, whereas in two aneuploid human glioblastoma cell lines, targeted correction of the endogenous mutant alleles of STAG2 led to enhanced chromosomal stability. Thus, genetic disruption of cohesin is a cause of aneuploidy in human cancer.     

Molecular and Physical Mapping of Powdery Mildew Resistance Genes and QTLs in Wheat: A Review

Wheat powdery mildew(Pm) is a major disease of wheat worldwide. During the past years, numerous studies have been published on molecular mapping of Pm resistance gene(s) in wheat. We summarized the relevant findings of 89 major resistance gene mapping studies and 25 quantitative trait loci(QTL) mapping studies. Major Pm resistance genes and QTLs were found on all wheat chromosomes, but the Pm resistance genes/QTLs were not randomly distributed on each chromosome of wheat. The summarized data showed that the A or B genome has more major Pm resistance genes than the D genome and chromosomes 1A, 2A, 2B, 5B, 5D, 6B, 7A and 7B harbor more major Pm resistance genes than the other chromosomes. For adult plant resistance(APR) genes/QTLs, B genome of wheat harbors more APR genes than A and D genomes, and chromosomes 2A, 4A, 5A, 1B, 2B, 3B, 5B, 6B, 7B, 2D, 5D and 7D harbor more Pm resistance QTLs than the other chromosomes,suggesting that A genome except 1A, 3A and 6A, B genome except 4B, D genome except 1D, 3D, 4D, and 6D play an important role in wheat combating against powdery mildew. Furthermore, Pm resistance genes are derived from wheat and its relatives, which suggested that the resistance sources are diverse and Pm resistance genes are diverse and useful in combating against the powdery mildew isolates. In this review, four APR genes, Pm38/Lr34/Yr18/Sr57, Pm46/Lr67/Yr46/Sr55, Pm?/Lr27/Yr30/Sr2 and Pm39/Lr46/Yr29, are not only resistant to powdery mildew but also effective for rust diseases in the field, indicating that such genes are stable and useful in wheat breeding programmes. The summarized data also provide chromosome locations or linked markers for Pm resistance genes/QTLs. Markers linked to these genes can also be utilized to pyramid diverse Pm resistance genes/QTLs more efficiently by marker-assisted selection.     

水稻品种Acc8558抗白叶枯病的抗性基因定位

以高抗白叶枯病水稻品种 Acc8558和高感品种 H359为亲本 ,采用单粒传方法建立一个重组自交系群体 ,利用该群体构建了一张包含 2 2 5个分子标记的连锁图 .1996、1997年对该群体连续 2 a进行了白叶枯病抗性鉴定 ,并对白叶枯病抗性基因进行了定位分析 .结果表明 ,白叶枯病的抗性由 1对主效基因控制 ,且存在一些微效的修饰基因 .该主效基因位于第 5号染色体的 R830与 P2 2 / M17- 4两标记之间 ,距 R830和 P2 2 / M17- 4的距离分别约为 4 .8c M和 6 .1c M     

Aneuploidy drives genomic instability in yeast

Aneuploidy decreases cellular fitness, yet it is also associated with cancer, a disease of enhanced proliferative capacity. To investigate one mechanism by which aneuploidy could contribute to tumorigenesis, we examined the effects of aneuploidy on genomic stability. We analyzed 13 budding yeast strains that carry extra copies of single chromosomes and found that all aneuploid strains exhibited one or more forms of genomic instability. Most strains displayed increased chromosome loss and mitotic recombination, as well as defective DNA damage repair. Aneuploid fission yeast strains also exhibited defects in mitotic recombination. Aneuploidy-induced genomic instability could facilitate the development of genetic alterations that drive malignant growth in cancer.     

Mapping and Candidate Gene Screening of Tomato Yellow Leaf Curl Virus Resistant Gene ty-5

To identify the inheritance pattern and perform fine mapping of ty-5 gene, P_1, P_2, F_1, BC_1 and F_2 generations were obtained through a cross between CLN32120 a-23(containing ty-5 gene, P_1) and S. lycopersicum Moneymaker(fully susceptible, P_2). The results showed that resistance of ty-5 gene was determined by a recessive effect. Meanwhile, it was presumed that another resistance gene might be involved in mediating the resistance to tomato yellow leaf curl virus(TYLCV). In this study, fine mapping was used to map TYLCV resistance locus to an interval between NAC1 and TES2461 on the short arm of chromosome 4 with genetic distances of 0.5 and 0.8 cM, respectively. qRT-PCR results showed that four candidate genes, SlNAC1; LOC104229164; LOC101260925 and LOC101261508 having resistance-related expression patterns, were the likely target genes of ty-5. In addition, it was found that the codominant marker TES2461 could be used in marker-assisted selection(MAS) breeding. The findings of this research provided the basis for future cloning of ty-5 gene as well as MAS breeding and plant resistance mechanism studies.     

溴氰菊酯在家蝇体内诱导蛋白的二维电泳分析

家蝇经过溴氰菊酯１２代的筛选，抗性品系的ＬＤ５０是敏感品系的１７．５倍，且与有机磷类杀虫剂无交互抗性。进一步对成虫的双向电泳结果显示，抗性品系中至少有３个多肽点在敏感品系中未出现，这些点很可能就是由抗药性基因诱导产生的抗性蛋白质。而由敏感品系表达的一些蛋白却在抗性品系中缺失，可能是抗药性基因的被诱导而抑制了另外一些基因的表达。     

Identification of molecular markers linked to rice bacterial blight resistance genes from Oryza meyeriana

Y73 is a progeny of asymmetric somatic hybridization between Oryza sativa cv. Dalixiang and the wild rice species Oryza meyeriana. Inoculation with a range of strains of Xanthomonas oryzae pv. oryzae showed that Y73 had inherited a high level of resistance to rice bacterial blight (BB) from its wild parent. An F₂ population of 7125 individuals was constructed from the cross between Y73 and a BB-susceptible cultivar IR24. After testing 615 SSR and STS markers covering the 12 rice chromosomes, 186 markers were selected that showed polymorphism between Y73 and IR24. Molecular markers linked to the BB resistance genes in Y73 were scanned using the F₂ population and the polymorphic markers. The SSR marker RM128 on chromosome 1, the STS marker R03D159 on chromosome 3 and the STS marker R05D104 on chromosome 5 were found to be linked to the rice BB resistance genes in Y73.     

水稻抗白叶枯病基因在物理图谱上的锚定

到目前为止,经国际注册确认和期刊报道的水稻白叶枯病抗性基因共35个。已被定位的抗性基因有26个,即第1染色体上有2个,Xa29(t)和xa34(t);第3染色体上有Xa11;第4染色体上有6个,Xa1、Xa2、Xa12、Xa14、Xa25(t)、Xa31(t);第5染色体上有xa5;第6染色体上有3个,Xa7、Xa27(t)、xa33(t);第7染色体上有xa8;第8染色体上有xa13;第11染色体上有9个,Xa3/Xa26、Xa4、Xa10、Xa21、Xa22(t)、Xa23、Xa30(t)、Xa32(t)、Xa36(t);第12染色体上有2个,xa25、xa32(t)。Xa1、xa5、xa13、Xa21、Xa23、xa25、Xa26、Xa27已成功克隆。文中利用GRAMENE网站公布的抗白叶枯病基因的分子标记,在日本晴的测序图谱Gramene Annotated Nipponbare Sequence 2009上进行物理图谱锚定,将已定位的26个抗白叶枯病基因锚定在其物理图谱的26个位点上,为抗白叶枯病基因的基因克隆、分子标记辅助选择奠定了基础。     

Female germ cell aneuploidy and embryo death in mice lacking the meiosis-specific protein SCP3

Aneuploidy (trisomy or monosomy) is the leading genetic cause of pregnancy loss in humans and results from errors in meiotic chromosome segregation. Here, we show that the absence of synaptonemal complex protein 3 (SCP3) promotes aneuploidy in murine oocytes by inducing defective meiotic chromosome segregation. The abnormal oocyte karyotype is inherited by embryos, which die in utero at an early stage of development. In addition, embryo death in SCP3-deficient females increases with advancing maternal age. We found that SCP3 is required for chiasmata formation and for the structural integrity of meiotic chromosomes, suggesting that altered chromosomal structure triggers nondisjunction. SCP3 is thus linked to inherited aneuploidy in female germ cells and provides a model system for studying age-dependent degeneration in oocytes.     

544份水稻种质稻瘟病抗性鉴定及抗性基因的分布研究

采用苗期喷雾接种鉴定方法并结合10个主效抗性基因的特异性分子标记检测,分析544份水稻种质资源的稻瘟病抗性水平及其携带的抗性基因分布情况。结果表明:稻瘟病抗性水平达高抗、抗、中抗、中感、感及高感的材料分别为25、50、78、152、156和83份;10个分子标记对应的抗病基因在供试材料中均被检测到,含有2和3个抗性基因的材料分别为4和17份(占0.7%和3.1%),476份材料含有4~6个抗性基因(占87.5%),47份材料含有7个抗性基因(占8.6%);品种抗病反应与其抗病基因种类密切相关,Pi5、Pita、Pi9、Pib等4个基因对6个强致病鉴定小种抗性表现较好。隆粳968、秀水134、嘉58、津稻263、淮稻20号、盐稻10号、谷梅4号等品种含有多个主效抗病基因,连续多年达到高抗水平。利用分子标记辅助选择将不同来源的主效抗病基因聚合到同一品种中,是控制该病害最经济有效的途径。     

大豆抗大豆花叶病毒病基因研究进展

大豆花叶病毒(soybean mosaic virus,SMV)病是严重危害世界大豆(Glycine max(L.)Merr.)生产的主要病害之一。近十年来,国内外关于大豆对SMV抗病基因的遗传标记定位、候选抗病基因的分析及大豆抗SMV的调控网络等研究取得许多新进展。大豆对SMV的抗性遗传主要分为数量抗性和质量抗性,其中数量抗性的遗传主要由1对加性主基因+加性-显性多基因共同控制;对不同SMV株系的质量抗性遗传分别由1对不同的显性基因控制。标记定位研究发现,大豆对SMV数量抗性位点主要分布在大豆的第6、10和13等染色体上。22个对SMV具有单显性质量抗性的基因位点已被标记定位在大豆的第2、6、13和14染色体上,且定位的多数抗病基因位点两侧标记间的物理距离都在1 Mb以内。其中第13染色体上的基因位点数最多,有Rsv1、Rsv5、RSC3Q、RSC11和RSC12等10个,定位在第2染色体上的基因位点有8个,如Rsv4、RSC5、RSC6、RSC7和RSC8等,第6和14染色体上各有2个基因位点,分别为RSC15、RSC18和Rsv3、RSC4。参考大豆全基因组序列(http://www.phytozome.net/soybean),利用生物信息学方法、表达谱分析及克隆测序技术等进一步缩小了大豆抗SMV候选基因的筛选范围。目前,在大豆第2染色体上确定的抗SMV候选基因主要有8个:Glyma.02G121400、Glyma.02G121500、Glyma.02G121600、Glyma.02G121800、Glyma.02G121900、Glyma.02G122000、Glyma.02G122100和Glyma.02G122200,在第6染色体上的是Glyma.06G182600,在第13和14染色体上的抗SMV候选基因分别有9个和6个:Glyma.13G184800、Glyma.13G184900、Glyma.13G187900、Glyma.13G190000、Glyma.13G190300、Glyma.13G190400、Glyma.13G190800、Glyma.13G194700、Glyma.13G195100和Glyma.14G204500、Glyma.14G204600、Glyma.14G204700、Glyma.14G205000、Glyma.14G205200、Glyma.14G205300。基于病毒诱导的基因沉默VIGS(virus induced gene silencing,VIGS)和转基因操作等技术,研究发现抗SMV相关基因Gm HSP40、Gm PP2C3a、Gm AKT2、Gm Cnx1、Gm SN1、Glyma.14G204500、Glyma.14G204600、Glyma.14G204700等参与大豆对SMV的抗性,属于正调控因子;而Gm EF1A和Gme IF5A等则增加大豆对SMV的易感性,为负调控因子。在综合SMV抗病基因的相关研究基础上,构建了基于Rsv1和Rsv3介导对SMV极端抗性的调控网络模型。Rsv1介导的大豆对SMV极端抗性调控模型的建立为大豆抗SMV信号网络的研究提供了新的方向。Rsv3介导的大豆对SMV极端抗性的主要机制是通过ABA信号的传导,从而使胞间连丝处的胼胝质沉积以抑制病毒从最初侵染的细胞向健康细胞的转移。本文系统综述了SMV抗病基因方面的最新研究成果并对该领域未来的研究方向进行了展望,以期为大豆抗SMV分子设计育种和抗病基因的机理研究提供参考。     

养殖鱼塘中铜绿假单胞菌致病性及耐药相关基因的研究

旨在分析养殖鱼塘水体中铜绿假单胞菌(Pseudomonas aeruginosa,PA)分离菌株的致病性、耐药性及其可能机制,为保障水产食品的安全提供科学依据。使用美国临床与实验室标准研究所的标准纸片扩散法,以及聚合酶链反应技术对PA分离菌株进行了抗菌素耐药性,以及毒性、固有和获得性耐药相关基因的检测与分析。结果显示,受试PA分离菌株的50%为exoS+/exoU-侵染型分子型,无临床分离菌株的exoS-/exoU+的细胞毒型分子型。PA菌株对6大类9种抗菌素的耐药性存在明显差异,其中甲氧胺苄嘧啶和利福平的耐药率最高为100%,其次是氨苄西林、卡那霉素和四环素,分别为90%、90%和80%,庆大霉素的耐药率最低为10%。多药抗性PA菌株均含有MexAB-OprM、MexXY-OprM和MexVW-OprM外排泵系统,其中20%菌株检测为β-内酰胺酶基因(ampC)阳性;而MexEF-OprN、MexJK-OprM、MexCD-OprJ和MexGHI-OpmD外排泵基因全部或部分缺失。此外,在PA菌株中均未检测到Ⅰ～Ⅲ类整合子的整合酶基因(comINT),但是整合接合元件(ICEs)保守模块功能基因(ICEint、soj、pilS2、pilD)均检测为阳性,提示PA菌株携带的ICEs具有潜在的转移活性,为进一步探讨PA多药抗性的散播奠定了基础。     

番茄第9号染色体上抗晚疫病基因的发掘及表达模式

为提供番茄晚疫病抗病育种候选基因,本研究以高抗晚疫病的CLN2037E自交系和感病5#自交系为实验材料,在前期使用分子标记将CLN2037E中存在的抗晚疫病基因定位在第9号染色体的基础上,利用晚疫病病菌诱导CLN2037E的cDNA文库、番茄基因组CDS数据库、本地Blast程序及实时荧光定量PCR技术,发掘与第9号染色体上EST最佳匹配的CDS以及对晚疫病病菌的响应模式。结果发掘出6条抗晚疫病的候选基因,其中Solyc09g097960、Solyc09g082810和Solyc09g065760在5#自交系和CLN2037E自交系中均响应晚疫病病菌,Solyc09g092030和Solyc09g090430在2个自交系中分别被抑制和不响应晚疫病病菌,Solyc09g008670STBZ的表达在5#自交系中被抑制,而在CLN2037E中被诱导。为验证该基因的功能,成功构建Solyc09g008670基因的过表达和VIGS(Virus Induced Gene Silencing)沉默载体。     

黄瓜倍性材料创制及染色体组成的FISH鉴定

【目的】黄瓜（Cucumis sativus L.）遗传基础狭窄,种质资源多样性较为有限,遗传育种研究相对落后。本试验旨在创制整倍体和非整倍体黄瓜种质材料,建立其准确的染色体组成鉴定方法,为进一步选育黄瓜各种染色体系、目标性状的染色体定位及遗传育种研究奠定基础。【方法】以华北生态型黄瓜‘长春密刺’的高代自交系为材料,0.4％秋水仙素溶液处理萌动种子,诱导染色体数目加倍。为获得同源三倍体材料,以诱导获得的同源四倍体为母本,二倍体为父本进行杂交,授粉35-45 d后采收成熟果实进行胚拯救。采用染色体计数,结合形态学、叶片气孔电镜观察,对诱导株及杂交后代的倍性进行鉴定。利用染色体特异的探针进行荧光原位杂交（fluorescence in situ hybridization,FISH）,通过观察特异探针在染色体上杂交信号的数目、强弱及位置,结合黄瓜的染色体形态参数,对诱导株的染色体组成进行鉴定。【结果】对经秋水仙素处理的‘长春密刺’材料进行有丝分裂中期染色体计数观察,结果显示诱导获得8株四倍体（2n=28）,3株非整倍体（2n=16,19,27）材料。将四倍体与二倍体杂交获得了三倍体材料（2n=21）。经荧光原位杂交分析,根据黄瓜着丝粒探针Type III和核糖体45S rDNA两类信号在染色体上的信号特征可以看出,与二倍体相比,三倍体与四倍体上杂交信号为倍性变化关系,进一步验证创制出的整倍性材料为三倍体与四倍体。不同倍性‘长春密刺’植株的形态学特征存在一定差异,四倍体植株的形态指标与二倍体差异显著;三倍体植株与二倍体在形态学上差异不显著;非整倍体植株与二倍体在形态学上差异也不显著,但其长势较二倍体弱,且花期推迟,雌雄花花期不遇,坐果率明显低于二倍体。经叶片气孔电镜观察,‘长春密刺’二倍体、三倍体与四倍体植株叶片气孔的大小与密度均存在差异,随着倍性提高,气孔的长度和宽度增加,而气孔密度则下降,说明形态学筛选和叶片气孔电镜观察可以作为鉴定黄瓜倍性的辅助方法。以上述两类黄瓜重复序列（Type III和45S rDNA）和染色体特异的单拷贝基因Csa006700为探针,对染色体数目为16的一株非整倍体诱导株进行染色体组成鉴定。重复序列的荧光原位杂交结果显示,额外的两条染色体为1号或2号染色体。进一步利用黄瓜2号染色体端部的基因Csa006700探针检测,发现该基因只在其中一对染色体上有信号,由此明确该材料为附加两条1号染色体的四体材料（2n=14+2）。研究表明秋水仙素不仅可直接诱导出同源多倍体,同时可诱导各种非整倍体植株。【结论】利用秋水仙素处理黄瓜萌动种子,诱导染色体倍性的变化,结合染色体特异探针的荧光原位杂交鉴定,可快速创制并筛选出各种染色体组成的特异新种质。     

马铃薯晚疫病抗性相关基因定位及QTL位点分析

【目的】寻找与马铃薯晚疫病水平抗性紧密相关的候选基因,以期作为分子标记辅助选择的重要标记。【方法】以BCT和PCC1两个马铃薯群体为材料,对38个晚疫病菌诱导表达的ESTs和基因进行定位,再将定位结果与已定位的QTL位点进行比对。【结果】11个候选基因的引物在两个群体中扩增出13个多态性位点,其中12 个多态性位点定位到遗传连锁图谱上。定位结果与QTL进行比较显示,07-F08-P1-564位于晚疫病QTL区域。【结论】07-F08-P1-564与马铃薯晚疫病水平抗性紧密相关。定位的候选基因丰富了马铃薯的连锁群,可作为遗传连锁图谱构建的桥梁,同时也为筛选重要抗性候选基因奠定了基础。