中国山羊品种资源及其遗传多样性研究

本文论述了中国山羊的起源、品种遗传资源及其遗传多样性的研究进展。最新调查 显示中国的山羊品种达50个,其中43个为地方品种,4个培育品种,3个引入品种,许多品种 具有独特的生产性能或适应能力。大量研究表明,我国山羊遗传多样性较为丰富。     

Genetic variability within Phaeoisariopsis griseola from Central America and its implications for resistance breeding of common bean

The genetic and virulence variability of 112 isolates of Phaeoisariopsis griseola , collected from various locations in Central America, were studied using seven random amplified polymorphic DNA (RAPD) primers and 12 common-bean differential genotypes. Broad molecular diversity ( H  = 0·92) among isolates was found using RAPD markers. Fifty pathotypes were identified on 12 differential bean genotypes, 29 of which were represented by only one isolate. Only 18 pathotypes were found in two or more countries. Pathotype 63-63 was the most virulent and caused leaf spots on all 12 common-bean differential genotypes. Comparison of virulence phenotypes and RAPD profiles to known Andean P. griseola isolates confirmed that all isolates belonged to the Mesoamerican group. Pairwise comparison between individual RAPD loci showed that the majority were in gametic phase linkage disequilibrium, revealing that P. griseola maintains a genetic structure that is consistent with asexual reproduction. The molecular and virulence diversities of P. griseola isolates from Central America imply that using single resistance genes to manage angular leaf spot is inadequate and stacking resistance genes may be necessary to manage the disease effectively.     

Comparison of Crinipellis perniciosa isolates from Brazil by ERIC repetitive element sequence-based PCR genomic fingerprinting

Fifty isolates of Crinipellis perniciosa originating from Theobroma cacao , Heteropterys acutifolia and Solanum lycocarpum , from six states within Brazil, were characterized through ERIC-PCR, representing the first application of this method for molecular characterization within C. perniciosa . Phenetic analysis of banding patterns revealed a separation of isolates on the basis of host of origin, with T. cacao -derived isolates showing only a 0·2 similarity level to a cluster comprising the isolates from H. acutifolia and S. lycocarpum . Considerable intraspecific variability was observed within C. perniciosa isolates from T. cacao , with distinct groups observed correlating with geographical origin. Given that a number of isolates from T. cacao from the Amazon region grouped with isolates from Bahia state, this work discusses the possibility that current C. perniciosa populations pathogenic on T. cacao in Bahia originated from the Amazon region, rather than from alternative host plants.     

SSR-based genetic linkage analysis of resistance to crown rust (Puccinia coronata f. sp. lolii) in perennial ryegrass (Lolium perenne)

Crown rust (caused by Puccinia coronata f. sp. lolii) is a serious foliar disease of the pasture and turfgrass perennial ryegrass (Lolium perenne). Previous genetic studies have detected both qualitative and quantitative resistance mechanisms, and interpretation of the genetic system is complicated by variation within the sexually reproducing pathogen. Resistant and susceptible parental genotypes of ryegrass were identified using a composite urediniospore population collected from three geographically distinct locations. A two-way pseudo-testcross mapping population was obtained as the F₁ progeny of the pair-cross between ryegrass parental genotypes Vedette₆ and Victorian₉. Both parents showed intermediate resistance against a pathogen population collected in a single geographical zone (Hamilton, Victoria), but in the F₁ population, significant variation for a range of resistance-associated characters was detected. Statistical analysis of phenotypic data suggested a major gene effect, hence bulked segregant analysis with map-assigned simple sequence repeat (SSR) markers was used to scan the genome. A marker showing strong association with resistance was assigned to linkage group (LG) 2 of perennial ryegrass. Analysis of 11 LG2 SSR markers defined an interval between loci xlpssrh03f03 and xlpssrk02e02 as containing the gene or genes (LpPc1) conferring crown rust resistance. Resistance gene determinants were inherited from both parents, with up to 80% of the total phenotypic variation explained by markers segregating from Vedette₆ and up to 26% of the variation explained by markers segregating from Victorian₉. The two contributions together resulted in an additive increase in effect, with fully resistant individuals requiring determinants from both parents. A conserved syntenic relationship was observed with linkage group B of Avena strigosa, which is the location of a cluster of resistance genes to the oat form of crown rust. The implications of this study for marker-assisted selection of disease resistance in perennial ryegrass are discussed.     

Inconspicuous restraint of rice seedling growth by root-infecting fungi in soil of a rice paddy field

 Rice seedling growth, estimated by plant height and root development and discoloration, was better in pasteurized soil than in unpasteurized soil obtained from a flooded rice field. Rice seedlings also grew better in sterilized soil modified by adding roots harvested from the pasteurized soil than in soil modified by adding roots harvested from the unpasteurized soil. The results demonstrate that seedling growth in the rice field soil was inhibited by soil microorganisms, even though no typical symptoms such as seedling blight or damping-off appeared. Pythium aristosporum is suggested to be involved in the inhibition. Thus, it appears that inconspicuous restraint of rice seedling growth could occur in soils of rice paddy fields. Received: May 20, 2002 / Accepted: October 16, 2002 Acknowledgments The authors thank Dr. T. Ichitani, former professor at Osaka Prefectural University, for providing an isolate of Pythium aristosporum for comparison, and Mr. Mitsuaki Sato of Akita Prefectural College of Agriculture for technical assistance.     

扩增片段长度多态性（AFLP）在动物遗传育种中的应用进展

AFLP是一种新的分子遗传标记技术，它结合了RFLP和PCR技术的优点，具有RFLP的稳定性和PCR的高效性，被称为“最有威力的分子遗传标记”或“下一代分子标记”。相对于国外而言，我国在这方面的研究还比较少。本文综述了扩增片段长度多态性(AFLP)这种遗传标记的原理、技术特点、技术发展及其在动物遗传多样性、种质鉴定、遗传图谱构建、基因定位和标记辅助育种等研究中的应用。     

闭锁群体BLUP选择下遗传方差和近交系数的变化

采用计算机随机模拟方法模拟了在一个闭锁群体内连续对单个性状进行 1 5个世代选择的情况。选择过程中世代不重叠 ,每个世代的种畜根据动物模型最佳线性无偏预测 (BLUP)法估计的育种值进行选留 ,并在此基础上系统地比较了不同群体规模、公母比例和性状遗传力对群体遗传方差和近交系数变化的影响。结果表明 ,扩大育种群规模、增加公畜比例以及对低遗传力性状进行选择时 ,群体遗传方差降低的速度和近交系数上升的速度会更慢 ,在长期选择时可望获得更大的持续进展和适宜的近交增量     

胞质雄性不育性在叶用芥菜上的利用

以从美国威斯康星大学引进的叶用芥菜胞质雄性不育系叶用4-4为母本,以泰国清迈大学选育出的8个优良叶用芥菜品种为转育父本,杂交后连续回交4代(BC4),再将BC4与优良叶用芥菜品种40R2-3-4配制8个杂交组合,其中2个组合(4-4 × 19-H-12)×40R2-3-4和(4-4 × 2R2)×40R2-3-4结球率为100％,产量比商用品种分别高34％和13％,比其亲本分别高25％和5％。     

利用微卫星标记分析贵州5个地方鸡品种遗传多样性

通过选用30个多态性较好的微卫星标记,检测了贵州省5个地方鸡品种:竹乡鸡、威宁鸡、黔东南小香鸡、高脚鸡、乌蒙乌骨鸡的遗传多样性。计算了各群体的平均遗传杂合度(H)、多态信息含量(PIC)和群体间的DA遗传距离。结果表明:在5个品种中,杂合度最低的是高脚鸡,为0.501,杂合度最高的是竹乡鸡,为0.673,因此贵州各地方鸡品种的杂合度相差较大,据分析可能是由于交通闭塞,形成了家禽品种的多种多型,而且杂合度的高低与PIC值的大小体现了较高的一致性;用UPGMA法进行聚类分析,结果6个鸡品种被聚为3类:竹乡鸡、黔东南小香鸡和威宁鸡聚为一类,乌蒙乌骨鸡自聚为一类;高脚鸡独自聚为一类。这与几个鸡品种的来源、分化、选育历史及地理分布是一致的。     

水牛精子在胞质内注射后的早期形态变化

应用胞质内精子注射 (intracytoplasmic sperm injection,ICSI)技术探讨了水牛卵母细胞胞质与注射精子间的相互作用以及 ICSI精子的形态变化。ICSI后 13h,5 9.4 %的精子头部已膨大 ,且有 18.8%的精子进入解聚状态。雌雄原核发育不同步 ,雄原核在 ICSI后 16 h和 19h的形成率分别为 3.2 %和 4 0 .0 % ;雌原核在 ICSI后 13h已达到 71.9% ,16 h时提高到 90 .3%。经离子霉素与 6 - DMAP联合激活 ,ICSI后 19h产生的胚胎核型以 2 PN PB1 为主 ,其雌原核形成 (激活 )率为 91.3% ,雄原核形成率为 4 0 .0 % ,5 1.3%为孤雌胚。用 5 mm ol/ L 的 DTT预处理精子 1h,可提高精子的解聚率 (30 .9%比 12 .7% ,P<0 .0 5 ) ,但对雄原核的形成率无显著影响 (33.3%比 32 .7% ,P>0 .0 5 )。结果表明 ,水牛精子 ICSI后的雄原核形成时间晚于卵子雌原核形成时间 ,且其比率低于卵子 ,DTT处理精子能提高其解聚率 ,但对雄原核形成无影响