Variation and distribution of virulence phenotypes of Bremia lactucae in natural populations of Lactuca serriola

During 1997–2000 the virulence variation and distribution of virulence phenotypes of Bremia lactucae (lettuce downy mildew) in natural populations of Lactuca serriola (prickly lettuce) were studied. Altogether 139 isolates of B. lactucae originating from the Czech Republic, France and Germany were examined for the presence of 27 virulence factors (v-factors) and their combinations. In the Czech population, 37 different v-phenotypes (P1–P37) of B. lactucae were found to occur on L. serriola . Most v-phenotypes were characterized by v-factors that match resistance ( Dm genes/R-factors) carried by L. serriola . A wide diversity of v-phenotypes was recorded every year, but most were rare and did not reappear in other populations of B. lactucae . The three v-phenotypes P21, P28 and P29 were most frequent and widely distributed. There was variation both between spatially isolated populations and within populations of the pathogen. Geographic differences in virulence were found for the southern parts of Moravia, where the phenotypic composition of pathogen populations was completely different from the remaining part of the area investigated. However, some populations had v-phenotypes similar to those of spatially distant populations in Moravia.     

Methods for studying population structure, including sensitivity to the fungicide silthiofam, of the cereal take-all fungus, Gaeumannomyces graminis var. tritici

Field isolates ( n  = 144) of the wheat take-all fungus Gaeumannomyces graminis var. tritici ( Ggt ) were tested for sensitivity to silthiofam, a take-all-specific fungicide used as a seed treatment, and identified as A- or B-type by PCR–RFLP analysis of nuclear rDNA. A possible association was identified between polymorphisms in ITS2 of the nuclear rDNA and sensitivity to silthiofam. A Ggt -specific PCR assay was developed which simultaneously identified isolates of Ggt as A- or B-type, based on the polymorphisms in the nuclear rDNA. A highly significant correlation between Ggt type using the PCR assay and sensitivity to silthiofam was demonstrated in a collection of 358 isolates from three field experiments designed to test the effects of seed-treatment fungicides on take-all and Ggt populations in winter wheat. In one experiment the percentages of silthiofam-sensitive and B-type isolates were significantly less in populations from plots sown with silthiofam-treated seed in two consecutive years than in populations from plots sown with nontreated seed. However, silthiofam still provided a significant amount of control of take-all. The natural occurrence of fungicide-insensitive isolates, up to about 30% in soils in which the fungicide had never been used, is unusual. The new PCR assay provides a useful tool for studying the population structure of Ggt , and may provide a novel method for assessing the incidence of insensitivity to silthiofam (the target site for which has not yet been identified) in field populations of Ggt .     

Genetic Diversity Analysis of Cultured Populations of Jade Perch （Scortum bacoo） in China Using AFLP Markers

Genetic diversity of three cultured populations of jade perch （Scortum bacoo） are studied using amplified fragment length polymorphism （AFLP） markers, which is Guangzhou（GZ） population, Foshan （FS） population and Qingdao（QD） population. Nine primer combinations were used and 385 fragments were detected. Among the 385 fragments, 80 bands （20.78%） were polymorphic. And it can be speculated that the genetic diversity of the three cultured populations of jade perch was very poor according to the gene genetic diversity among populations （Ht）, the gene genetic diversity within populations （Hs） and Shannon-Weiner index （I）. From gene differentiation （Gst）, genetic distance （D）, genetic similarity （5）, and UPGMA analysis, it is found that the relationship among the three populations is very closed, and the difference in genetic diversity among the three populations is not significant. Further clustering relationships of the jade perch cultured populations also are correlated to historical-breeding observations and genetic relationships. The GZ population clustered together with the QD population first, then with FS population.     

浅谈动物园的植物配置——以福州市动物园为例

动物园作为城市公园的一种,其植物配置具有其特殊性。分析动物园植物配置的特殊功能;在此基础上,以福州市动物园为例,探讨动物园植物配置问题,包括园区植物配置与展区植物配置。为其它同类动物园提供有益借鉴。     

不同地区福寿螺繁殖力比较

应用单对交配的方法对江苏、福建和广东3个不同地理群体福寿螺的繁殖力进行比较.结果显示,福寿螺的繁殖力变异较大;在个体产卵量方面,福建螺与江苏螺有显著差异(P<0.05);在雌螺个体体重的相对产卵量方面,广东螺与福建螺、广东螺与江苏螺有显著差异(P<0.05);不同地区、不同交配个体产卵块数差异不显著(P＞0.05);不同壳色的福寿螺繁殖力差异不明显(P＞0.05);交配个体雌雄大小不同其交配产卵量与雌螺个体大小呈正相关,与雄螺个体大小无关;雌螺个体越大产卵量越大,但相对产卵量反而越小;雌螺产卵量与卵块数呈正相关.福寿螺的繁殖力与环境条件、食物种类、温度等因素有密切的关系.     

三疣梭子蟹4个野生群体遗传差异的同工酶分析

采用聚丙烯酰胺不连续凝胶垂直电泳技术对三疣梭子蟹Portunus trituberbuculatus4个野生群体(鸭绿江口、莱州湾、海州湾和舟山)的同工酶进行检测,分析群体间的生化遗传差异.结果发现(1) 4个群体的多态座位百分数(P0.99)分别为:鸭绿江口13.6%、莱州湾13.6%、海州湾13.6%和舟山13.6%.(2) 4个群体间的生化遗传差异不显著,4个群体间的遗传距离D=0.000 54～0.001 70,属种内群体间差异.(3)聚类分析表明:4个群体分为两组,海州湾和舟山两群体之间的亲缘关系最近,聚为一组.莱州湾和鸭绿江口群体亲缘关系比较近,聚为另一组.     

云南省极小种群野生植物保护的优先度分析

我国于1997～2003年完成第1次全国重点保护野生植物资源调查后,为加强珍稀濒危和重点保护野生植物的保护,提出了“极小种群野生植物”的概念。随着极小种群野生植物概念和保护方法的完善,保护行动取得了显著进展,并陆续提出了各种不同的极小种群野生植物名录。本文在总结2005～2013年间云南省和国家林业局提出的所有极小种群野生植物名录基础上,分析了各极小种群野生植物名录的起源和关系,并对保护名录中的物种进行逐个比较。最后,结合国家和省的保护需求,将云南省77种极小种群野生植物分成5级,按优先度实施保护行动：第一批优先保护10个物种,第二批优先保护13个物种,第三批保护15个物种,第四批保护10个物种,第五批保护29个物种,为云南省极小种群野生植物保护提供了指导和参考。     

双柏恐龙河州级自然保护区保护价值评价

双柏恐龙河州级自然保护区内保存有较为完整的自然生态系统,生物多样性独特而丰富。文章在阐述保护区自然资源现状的基础上,结合其特点,从自然性、典型性、多样性、稀有性、脆弱性、科研价值等方面对保护区的保护价值进行了系统、全面的分析评价,认为该保护区重要生态系统和重要物种丰富,以热带季雨林和绿孔雀、滇南苏铁等为代表的生态系统及国家重点保护野生动植物,科学研究及保护价值巨大。     

云南松主分布区天然群体的遗传多样性及保护单元的构建

以20个云南松天然群体为对象,SSR分析表明云南松遗传变异主要存在于群体内,各群体间的遗传多样性水平差异不显著。基于SSR分子标记遗传多样性分析,根据Nei's遗传相似度,采用逐步聚类优先取样法,分别对初始群体、遗传多样性保护单元和剩余群体进行比较、t检验,以此评价遗传多样性保护单元的代表性。结果表明,利用该方法抽样的群体能很好地代表初始群体的遗传多样性,按30%的群体抽样,等位基因数、有效等位基因数、Shannon's信息指数和期望杂合度的保留率分别达到初始群体的98.03%、105.36%、103.99%和105.56%。保护单元的遗传多样性均高于剩余群体,抽样群体组成的遗传多样性保护单元的效果较好。