Selection forMeloidogyne incognita virulence against resistance genes from tomato and pepper and specificity of the virulence/resistance determinants

Experiments were designed to analyze the relationships between the root-knot nematodeMeloidogyne incognita and resistant tomato and pepper genotypes. From a natural avirulent isolate, near-isogenic nematode lineages were selected with virulence either against the tomatoMi resistance gene or the pepperMe3 resistance gene. Despite the drastic selection pressure used, nematodes appeared unable to overcome the pepperMe1 gene, therefore suggesting some differences in the resistance conferred byMe1 andMe3 in this species. Nematodes virulent onMi-resistant tomatoes were not able to reproduce onMe1-resistant nor onMe3-resistant peppers, and nematodes virulent onMe3-resistant peppers were not able to reproduce onMi-resistant tomatoes nor onMe1-resistant peppers. These results clearly demonstrate the specificity ofM. incognita virulence against resistance genes from both tomato and pepper, and indirectly suggest that gene-for-gene relationships could occur between these two solanaceous crops and the nematode.     

Mutants in wheat showing multipathogen resistance to biotrophic fungal pathogens

Five fast-neutron-derived mutants were isolated from the wheat line Hobbit 'sib' that show enhanced field resistance towards Puccinia striiformis f.sp. tritici , the causal agent of yellow rust. Subsequent testing showed the yellow rust resistance phenotypes to differ between mutants, to be expressed at different growth stages and, in some cases, to show an isolate interaction. Three mutants, I3-48, I3-49 and I3-54, exhibited an enhanced yellow rust resistance phenotype from the third seedling leaf onwards, while mutants I3-27 and I3-30 did not show an altered yellow rust phenotype until later growth stages. Additional resistance for brown rust (causal agent Puccinia triticina ) was identified in mutants I3-27, I3-30, I3-48 and I3-49, and for powdery mildew caused by Blumeria graminis f.sp. tritici in mutants I3-27, I3-30, I3-48 and I3-54, although in some cases the resistance was isolate-specific.     

Major Gene and Polygenic Resistance to Leptosphaeria maculans in Oilseed Rape (Brassica napus)

The most common and effective way to control phoma stem canker (blackleg) caused by Leptosphaeria maculans in oilseed rape (Brassica napus) is through the breeding of resistant cultivars. Race specific major genes that mediate resistance from the seedling stage have been identified in B. napus or have been introgressed from related species. Many race specific major genes have been described and some of them are probably identical in B. napus (allotetraploid AACC) and the parental species B. rapa (diploid AA). More work is needed using a set of well-characterised isolates to determine the number of different major resistance genes available. In some B. napus cultivars, there is resistance which is polygenic (mediated by Quantitative Trait Loci) and postulated to be race non-specific. Many of these major genes and Quantitative Trait Loci for resistance to L. maculans have been located on B. napus genetic maps. Genes involved in race specific and polygenic resistance are generally distinct.     

转rolA、B、C基因枳橙快繁技术

通过对转rol基因枳橙B、D、E系及对照的高接植株春梢茎段进行萌芽诱导、增殖及试管苗生根成苗的试验,摸索出适宜枳橙快繁各种培养基配方及培养条件。结果表明,以MS+6-BA1mg/L的培养基适合于芽萌发,以MS+6-BA0.5mg/L+NAA0.05mg/L的培养基适合于芽增殖,生根则以1/2MS+NAA0.5mg/L+0.2%活性炭的组合最佳,转基因各系生根率均在93.3%以上,显著高于对照生根率(66.7%)。快繁苗移栽成活率可达90%,目前生长良好。     

H9N2亚型禽流感病毒传播途径特性的比较及其表面基因序列分析

选择中国大陆最早分离的H9N2亚型禽流感病毒(avian influenza virus,AIV)A/Chicken/Guangdong/SS/94(H9N2)(缩写为SS株)和1998年大流行时期分离的H9N2亚型AIVA/Chicken/Shanghai/F/98(H9N2)(缩写为F株)为研究对象,对其在SPF鸡体内的复制能力和传播途径特性比较后发现,F株在4周龄SPF鸡气管中的复制能力高于SS株,F株可以经气溶胶传播途径传播,SS株不能经气溶胶传播途径传播;利用反转录-聚合酶链反应(RT-PCR)方法获取F株和SS株的HA和NA基因的cDNA,序列分析得知,F株和SS株的HA和NA基因的同源性分别是96.6%和98.1%;HA基因的裂解位点氨基酸序列都是PARSSR↓GL,但有5个氨基酸的差异,即166位N(F)→D(SS)、198位A(F)→V(SS)、217位V(F)→I(SS)、335位G(F)→R(SS)、504位L(F)→S(SS);2株病毒的NA基因在63~65位都存在氨基酸缺失,但在NA基因红细胞吸附位点的氨基酸序列不同,分别是IKKDSRSG(F)和IKEDLRSG(SS)。F株和SS株的传播特性差异是否与其表面基因序列有关,有待进一步研究。     

猪蛔虫感染期幼虫抑制消减cDNA文库的构建

为筛选与线虫感染性相关的基因,本研究以猪蛔虫为对象,构建猪蛔虫感染期幼虫差异表达消减cDNA文库,为研究线虫期特异性发育的分子机制奠定基础。分别提取感染期幼虫和其它各期幼虫及成虫的总RNA,纯化mRNA后,采用Clontech公司PCR-selectTM试剂盒进行反转录合成cDNA并进行抑制消减杂交(SSH),构建猪蛔虫感染期幼虫差异表达的消减cDNA文库,并采用Southern斑点杂交进行消减效率的检测。随机从文库中抽取45个克隆进行测序及在线BLAST分析。试验结果表明,感染期幼虫差异表达的消减cDNA文库具有较强的特异性;在得到的41个表达序列标签(ESTs)中,有40个ESTs与已报道的基因有较高的相似性,主要代表猪蛔虫第三期幼虫基因和成虫头部基因,有1个cDNA片段可能代表新基因。猪蛔虫感染期幼虫差异表达消减cDNA文库的成功构建,为进一步研究幼虫发育差异表达基因的功能奠定了基础。     

A群猪轮状病毒JS株vp7基因序列分析

根据已发表的猪轮状病毒OSU毒株vp7基因核苷酸序列ORF两端保守区序列,设计一对特异引物,以猪轮状病毒JS毒株反转录cDNA为模板,通过PCR方法扩增出长约1000 bp目的片段。将其进行T-A克隆、序列测定和分析。结果表明,vp7基因全长1062 bp,含有一个981 bp的开放阅读框,编码326个氨基酸。与已知的15个毒株vp7全长基因的核苷酸及推导的氨基酸序列比较,同源性分别为74.5%～78.5%和75.2%～83.1%,核苷酸系统发育进化树结果表明,JS毒株与轮状病毒G9型参考毒株ICB2185、O-1亲缘关系较近,分为一个群,表明JS毒株血清型为G9型。目前,我国尚未见猪及其它动物轮状病毒G9型流行株的报道。     

Screening differentially expressed genes involved in apoptosis of primary cultured rat cerebellar granule neurons by mRNA differential display RT-PCR

AIM: To Screen and identify differentially expressed genes that involved in apoptosis model in rat cerebellar granule neurons (CGNs).METHODS: The rat cerebellar granule neurons were isolated and primarily cultured.Fluorescent differential display RT-PCR (FDD RT-PCR) was performed to screen differentially expressed ESTs in the apoptosis model of primarily cultured rat CGNs.ESTs were subcloned into pGEM-T EasyTM vector and then sequenced.Alignment assay in non-redunant database was applied for encoding information.Reverse Northern blotting was used to appraise the results from DDRT-PCR.RESULTS: 164 pieces of differentially expressed ESTs were obtained by FDDRT-PCR.17 of them were subcloned and sequenced.5 ESTs of 17 were confirmed to be positive results by reverse Northern blotting.CONCLUSION: DD-PCR is a rapid,simple-operation and sensitive method for screening differentially expressed genes,which would contribute to the molecular mechanisms of apoptosis/survive of CGNs.     

杆状病毒非必需基因的结构与功能

本文主要以苜蓿丫纹夜蛾核型多角体病毒（ＡｃＭＮＰＶ）为例,概述了迄今展报道的杆状病毒非必需基因的结构与功能,为杆状病毒的基因工程研究提供参考。