垂叶榕瘿花发育特性的初步研究

研究榕属植物瘿花发育特性是理解榕树/榕小蜂协同进化内在机制的重要内容。本文解析了垂叶榕隐头花序伴随瘿花发育的 5 个发育时期，采用同工酶电泳的方法比较了瘿花与正常雌花同工酶（包括过氧化物酶、过氧化氢酶、淀粉酶和酯酶）谱带的差异，采用扫描电镜对比了瘿花壁与授粉后雌花子房壁的差异。结果表明，瘿花被榕小蜂产卵以后，至少启动了一个与消除过氧化物有关的酶；而且，瘿花子房壁结构疏松，内含物小而少，雌花子房壁结构致密且内含物多而大，说明瘿花发育所消耗的营养物质大于正常雌花发育的消耗。研究结果支持造瘿生物汇集营养与植物防御行为的互利假说。     

昆虫与植物协同进化的研究进展

从昆虫对植物的选择与适应、植物对昆虫的防御与适应、昆虫与植物的协同进化及其进化方式等方面综述了昆虫与植物协同进化的研究进展,并阐述了研究协同进化对害虫防治的意义。     

Pathogenic variation in, sources of, and breeding for resistance to Phaeoisariopsis griseola causing angular leaf spot in common bean

If we are to breed common bean (Phaseolus vulgaris L.) for durable resistance to diseases, we must understand pathogenic variation and find sources of resistance. Our first objective was to determine the patterns of pathogenic variation found among isolates of Phaeoisariopsis griseola (PG), the fungus that causes angular leaf spot (ALS) in common bean. We characterized 433 PG isolates from 11 Latin American and 10 African countries, using differential cultivars, isozymes, and/or random amplified polymorphic DNA (RAPD) markers. We also systematically screened, for ALS resistance, common bean accessions from the world collection held at CIAT, and assessed the progress so far made in breeding for resistance to ALS. Despite their great diversity within and between countries on both continents, the PG isolates were classified into two major groups: Andean, and Middle American. Although each group had internal differences for virulence, and biochemical and molecular characteristics, the ‘Andean’ PG isolates were more virulent on common beans of Andean origin, than on those of Middle American origin, thus, suggesting a host-pathogen co-evolution. The ‘Middle American’ PG isolates, although more virulent on common beans from Middle America, also attacked Andean beans, thus, exhibiting a much broader virulence spectrum. To find sources of resistance, we tested 22,832 common bean accessions against naturally occurring PG isolates in the field at CIAT's Experiment Station, Quilichao, Colombia, between 1985 and 1992. The resulting 123 intermediate (scores of 4 to 6) and resistant (scores of 1 to 3) accessions were then tested in the greenhouse against selected 14 PG isolates of diverse origins. Nineteen accessions were intermediate or resistant to at least 13 of 14 PG isolates. Similarly, of 13,219 bred lines tested in the field between 1978 and 1996, 89 were intermediate or resistant. Of these, 33 bred lines proved intermediate or resistant to at least eight of nine PG isolates to which they were challenged in the greenhouse. We suggest that, to breed for durable resistance to ALS, common bean populations should be developed from crosses between Andean and Middle American gene pools. The populations should then be systematically evaluated and selected against the broadest range of the most virulent PG isolates of diverse evolutionary origins. This revised version was published online in August 2006 with corrections to the Cover Date.     

Resistance to Meloidogyne chitwoodi,M. fallax and M. hapla in wild tuber-bearing Solanum spp.

Summary Over 5000 plants from 64 tuber-bearing wild Solanum spp. have been individually screened for resistance to Meloidogyne chitwoodi, M. fallax and M. hapla. Seedlings were analyzed by means of counting number of egg masses and resistance was verified by retesting low-scoring plants using stem cuttings. Resistance to both M. chitwoodi and M. fallax was observed in S. bulbocastanum, S. cardiophyllum, S. brachistotrichum, S. fendleri and S. hougasii. Only in S. chacoense and to a lesser extent in S. stoloniferum and S. gourlayi differential results between M. chitwoodi and M. fallax were observed. Resistance to M. hapla was found in S. bulbocastanum, S. brachistotrichum, S. cardiophyllum, S. arnezii, S. chacoense, S. tarijense, S. boliviense, S. gourlayi, S. microdontum, S. sparsipilum, S. spegazzinii, S. sucrense, S. acaule and S. hougasii. The occurrence of resistance in wild Solanum species in relation to their taxonomic status and the implications for introgression of resistance into S. tuberosum are discussed.     

基于自组织的农产品供应链机理及协同演化研究

首先从农产品供应链的目标参量、状态参量、控制参量和随机扰动因素深入分析农产品供应链自组织运作机理,认为农产品供应链目标的实现与成员企业的良好运作状态参量密不可分,而控制参量和随机扰动因素决定了成员企业的运作状态水平。以运作机理为基础构建农产品供应链协同演化模型,分析农产品供应链协同演化自组织过程和动力因素,以及农产品供应链在竞争阶段和协同阶段随机涨落力对供应链演化所起的作用,从而为农产品供应链协同管理提供理论依据。     

鸡(从)菌与白蚁的共生专一性初步研究

以鸡(从)菌(Termitomyces spp.)为指示菌,在云南地区的22个采集点和四川的1个采集点共解剖了97个蚁巢分析共生鸡(从)菌和白蚁的对应关系,并基于鸡(从)菌ITS序列和白蚁COⅡ序列,构建系统发育树,分析二者进化支系协同性.结果表明:真根鸡(从)菌(T.eurrhizus)、条纹鸡(从)菌(T.striatus)、盾尖鸡(从)菌(T.clypeatus)、小果鸡(从)菌(T.microcarpus)和空柄蚁巢伞(Sinotermitomyces cavus)5种鸡(从)菌与共生白蚁在种、属阶元均不具有共生专一性,协同进化迹象不明显.     

不同地理环境下野豌豆根瘤菌的遗传多样性与共生进化研究

【目的】研究西北部分地区不同地理环境下,野豌豆根瘤菌的遗传多样性及其共生进化间的关系。【方法】采用16S rDNA PCR-RFLP与16S rDNA全序列分析技术,对分离自陕西秦岭北麓红河谷、陕西南部汉中、甘肃沙漠绿洲带永昌混山窑、甘肃中部永登红城和新疆乌鲁木齐的5个不同地理环境(分别记做A、B、C、D、和E)的42株野豌豆根瘤菌,进行了遗传多样性和系统发育分析。【结果】测试根瘤菌共有6种基因型(Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ和Ⅵ),基因型Ⅰ根瘤菌在各个地理环境采样点均有分布,并且A地点分布的所有菌株均属于该基因型,基因型Ⅱ菌株分布于D和E采样地点,基因型Ⅲ菌株分布于B、C和D采样地点,基因型Ⅳ分布于E地点,基因型Ⅴ和Ⅵ测试菌株均分布于D地点。由16S rDNA全序列分析可知,基因型Ⅰ根瘤菌的代表菌株CCNWSX0050和基因型Ⅳ根瘤菌的代表菌株CCNWGS0055分别与Rhzobium leguminosarum的相似性为99.8%和99.7%;基因型Ⅲ根瘤菌的代表菌株CC-NWGS0062与Sinorhizobium meliloti的相似性为100.0%。【结论】中国西北地区野豌豆根瘤菌在分类学上属于Rhizobium leguminosarum根瘤菌和S.meliloti根瘤菌,野豌豆-根瘤菌的共生关系在不同地理环境中表现出差异性。     

Relationship between the Origin of European Landraces and the Level of Partial Resistance to Wheat Leaf Rust

The reaction to leaf rust of 33 European spring-wheat landrace selections was assessed in the field and in the greenhouse to study the relationship between levels of partial resistance and levels of leaf rust at the origin of the landrace selections. The selections were classified into three groups according to the mean annual damage observed at the collection site. For each group of selections with high-infection types the mean disease-severity, area under disease progress curve and latency period were assessed. The data suggest that there is a greater likelihood of finding partial resistance in selections that come from locations with a high or intermediate mean annual damage as they displayed lower disease severity, lower area according to a disease-progress curve and a longer latency period than the selections from locations with low mean annual damage.     

Interference competition between sunbirds and carpenter bees for the nectar of Hypoestes aristata

Interference competition for nectar sources has been repeatedly described between hummingbirds and various insects, but rarely recorded in other nectari-vorous birds. We observed aggressive behaviour by African sunbirds (Cinnyris reichenowi and Cinnyris bouvieri) defending the nectar plant Hypoestes aristata against carpenter bees (Xylocopa caffra and Xylocopa inconstans) in the Bamenda Highlands, Cameroon. During 200 hours of observation, we recorded 38 cases of the sunbirds attacking carpenter bees; all these intrusions occurred only in the flower-richest patches of the plant. We predict that similar aggressive interactions will occur between other Old World nectarivorous birds and insects. Such interference competition between distantly related taxa could have an important impact on the evolution of pollination systems.     

Virulence characteristics of apple scab (Venturia inaequalis) isolates from monoculture and mixed orchards

Isolates of Venturia inaequalis were sampled from monoculture and mixed orchards of three apple cultivars: Bramley, Cox and Worcester. In addition, single-ascospore progeny isolates were obtained from three crosses between pairs of isolates originating from the three cultivars in monoculture orchards. These field isolates and single-ascospore progenies were inoculated onto each of the three cultivars in a glasshouse. The patterns of infection showed that all three cultivars, commonly regarded as susceptible to scab, contained some specific resistance factors and that scab isolates from both mixed and monoculture orchards appeared to have co-evolved with cultivars. A much higher proportion of isolates from cv. Worcester in the mixed orchard were unable to infect any of the three cultivars than isolates from any other combination of cultivar and orchard type, but there was no other difference between isolates from mixed vs. monoculture orchards. Many isolates could infect both Bramley and Cox, or Cox and Worcester; but only a single isolate could infect both Bramley and Worcester. Results from the testing of 61 single-ascospore progeny isolates suggested that virulence towards Bramley, Cox and Worcester was controlled by at least one, two and three factors, respectively. Moreover, the exact nature of the interactions between these factors in determining virulence depended on the particular pair of isolates concerned.