麦二叉蚜唾液蛋白基因Sg1655时空表达谱及其抑制小麦防御反应的功能

为进一步明确麦二叉蚜Schizaphis graminum唾液蛋白Sg1655在调控小麦防御反应中的作用,基于麦二叉蚜唾液腺转录组数据,利用PCR技术克隆获取Sg1655开放阅读框,利用生物信息学软件对其序列进行分析;通过实时荧光定量PCR（real-time quantitative PCR,RT-qPCR）技术检测Sg1655在麦二叉蚜不同组织及不同龄期中的表达;利用细菌III型分泌系统将Sg1655导入到小麦叶片内,检测其瞬时表达对小麦胼胝质积累的影响。结果表明,Sg1655开放阅读框全长375 bp,编码125个氨基酸残基,N端1~21位为信号肽序列,预测蛋白分子量为14.90 kD。麦二叉蚜Sg1655氨基酸序列与玉米蚜Rhopalosiphum maidis同源序列相致性最高,为89.52%;麦二叉蚜Sg1655与玉米蚜同源序列聚为一个分支,亲缘关系最近。Sg1655在麦二叉蚜各组织中均有表达,其中在唾液腺中表达量最高,Sg1655在麦二叉蚜各个龄期均有表达,且在不同龄期之间无显著差异。小麦叶片内Sg1655瞬时表达可显著抑制小麦胼胝质积累,表明该蛋白可作为潜在效应子参与抑制小麦防御反应。     

Planted forests of the wet and dry tropics: their variety,nature, and significance

Planting trees in tropical countries is an increasingly important forestry activity. Although much attention has been paid, and rightly so, to rapid deforestation in the tropics, the contribution and role that planted forests can play are now at the center of policy and planning in most national forestry strategies. The changing emphasis from exploitative management of natural forests to managed natural forests and plantation forests, seen in temperate regions over the last 100 years, has been taking place in tropical countries largely over the last 20 years. In neither temperate nor tropical regions has this evolution finished.Planted forests will increasingly furnish wood resources that meet domestic wood needs and provide many environmental services. In this paper I seek to place in perspective the contribution that planted forests will make in the tropics. I emphasize (1) the wide variety of purposes that planted forests serve; (2) the sustainability of plantation silviculture; and (3) the overriding importance of due regard to people's participation. I am optimistic about the great value that planted forests, rightly used, can provide for a great many hard-pressed peoples across the tropics and beyond.     

Habitat characterization,anthropogenic impacts and conservation of rhodolith beds off southeastern Malta

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A shifting algorithm to simulate thinnings from below and above

Thinning is a silvicultural practice to improve tree growth and health. Thinning from below for the even-aged silviculture and thinning from above for the uneven-aged silviculture are the two mainly applied thinning practices. In forest management simulations, algorithms that describe which individual trees to be removed from a forest have developed in five growth simulators (Söderbergh and Ledermann, 2003). We have developed a shifting algorithm that determines the proportion of trees to be thinned from different diameter classes to complement the individual tree selection algorithms. Sampled (or mapped) tree diameters are grouped into diameter classes. Given the target thinning volume, the algorithm automatically computes the thinning rate in each of the diameter classes using the three-parameter Weibull distribution. The thinning rate is obtained by shifting the location parameter of an estimated Weibull distribution either to the right or to the left for thinnings from below and above, respectively. A modified bisection method is used to search for the new location parameter that yields the desired thinning volume. The proposed algorithm is demonstrated in examples by using experimental forest datasets. A stand-alone program called Weibull_thinning is downloadable at http://www.it.abo.fi/suswood/weibull_thinning/.     

Using metabolic profiling to assess plant-pathogen interactions: an example using rice (<Emphasis Type="Italic">Oryza sativa)</Emphasis> and the blast pathogen <Emphasis Type="Italic">Magnaporthe grisea</Emphasis>

A metabolomics based approach has been used to study the infection of the Hwacheong rice cultivar (Oryza sativa L. cv. Hwacheong) with compatible (KJ201) and incompatible (KJ401) strains of the rice blast fungal pathogen Magnaporthe grisea. The metabolic response of the rice plants to each strain was assessed 0, 6, 12, 24, 36, and 48 h post inoculation. Nuclear Magnetic Resonance (NMR) spectroscopy and Gas and Liquid Chromatography Tandem Mass spectrometry (GC/LC-MS/MS) were used to study both aqueous and organic phase metabolites, collectively resulting in the identification of 93 compounds. Clear metabolic profiles were observed at each time point but there were no significant differences in the metabolic response elicited by each pathogen strain until 24 h post inoculation. The largest change was found to be in alanine, which was ~30% (±9%) higher in the leaves from the compatible, compared to the resistant, plants. Together with several other metabolites (malate, glutamine, proline, cinnamate and an unknown sugar) alanine exhibited a good correlation between time of fungal penetration into the leaf and the divergence of metabolite profiles in each interaction. The results indicate both that a wide range of metabolites can be identified in rice leaves and that metabolomics has potential for the study of biochemical changes in plant-pathogen interactions.     

菜蛾绒茧蜂生物学研究

菜蛾绒茧蜂(Apanteles plutellae Kurbjumov)是小菜蛾(plutella xylo-stella L.)幼虫非群栖性的寄生蜂。在杭州室内条件下,每年发生15代。以预蛹越冬。除越冬代外,发育历期与日平均温度的回归式为Y=52.4-1.5x±2.4(天)产卵期最长17天。能寄生各龄小菜蛾幼虫,但以2～3龄为宜。每雌最大有效子蜂数235头,日出茧量最高38头。周年雌雄性比1:0.8。孤雌生殖后代纯为雄蜂。田间最高自然寄生率59.4％。莱蛾啮小蜂(Tetrastichus sokol-owskii)是最重要的重寄生物,又是小菜蛾幼虫到蛹的寄生蜂。     

土壤施硅对小麦和麦蚜的影响

为明确土壤施硅对小麦蚜虫的防控效果,本研究在小麦种植前分别配施0（CK）、40、80和120 kg/hm²四个浓度的硅肥,测量施硅后小麦生育期、生物量、叶面积、株高、产量指标以及荻草谷网蚜Sitobion miscanthi和禾谷缢管蚜Rhopalosiphum padi发生量。结果表明,施硅对小麦株高和穗数无显著影响,但80 kg/hm²和120 kg/hm²浓度施硅处理后小麦叶面积分别为1 786.03 mm²和2 033.54 mm²,生物量分别为133.68 g和134.50 g,小麦穗粒数分别为35.61粒和35.92粒,小麦千粒重分别为45.34 g和45.59 g,小麦产量分别为9 684.45 kg/hm²和9 835.05 kg/hm²,均显著高于对照,且小麦成熟期较对照提前3 d;80 kg/hm²和120 kg/hm²浓度施硅处理后禾谷缢管蚜发生量分别为90头和86头,均显著低于对照;40、80和120 kg/hm²浓度施硅处理后荻草谷网蚜发生量分别为128、117和105头,均显著低于对照。因此,田间土壤施硅80 kg/hm²和120 kg/hm²可以明显改善小麦农艺性状,提高小麦产量,并能减少麦蚜发生量。     

Simultaneous temporal progress of sorghum anthracnose and leaf blight in crop mixtures with disparate patterns

Field studies were conducted at Alupe in western Kenya in 1995 and 1996 to evaluate the efficacy of crop and species mixtures for the management of sorghum anthracnose (caused by Colletotrichum sublineolum) and leaf blight (caused by Exserohilum turcicum). The progress of these diseases developing simultaneously on a susceptible sorghum cultivar planted in inter- or intra-row mixtures of varying proportions with either maize or resistant sorghum was monitored. The effects of host type and mixture patterns on disease progress were compared by parameter estimates derived from fitted Lotka-Volterra competition equations and nonlinear logistic models. Competition coefficients were not significant and their confidence intervals included zero in most cases, suggesting that interactions between C. sublineolum and E. turcicum did not occur. Mixtures of the susceptible sorghum with either the nonhost maize or the resistant sorghum delayed the time when disease is first observed and reduced the rate of disease progress and carrying capacity for both anthracnose and leaf blight, with a more pronounced effect on the latter disease. The lower efficacy of mixtures in reducing anthracnose was attributed to an aggregated spatial pattern, coupled with higher rates of progress for this disease. Intra-row mixtures were more efficient than inter-row mixtures in reducing disease development in all years. The implications of these observations for the management of sorghum diseases under small-scale farming systems are discussed.     

Identification of candidate genes required for susceptibility to powdery or downy mildew in cucumber

Powdery mildew (PM, caused by Podosphaera fusca) and downy mildew (DM, caused by Pseudoperonospora cubensis) are important diseases of cucumber (Cucumis sativus). Breeding for resistance has been undertaken since the 1940s, but underlying resistance genes have not been functionally analysed yet. The published genome sequence of cucumber catalyses the search for such genes. Genetic studies have indicated that resistances to PM and DM in cucumber are often inherited recessively, which indicates the presence of susceptibility genes (S-genes). Therefore we analyzed the cucumber genome for homologs of functionally proven S-genes known from other plant species. We identified 13 MLO-like genes in cucumber, three of which cluster in Clade V, the clade that contains all known MLO-like susceptibility genes to powdery mildews in other dicots. The expression of one of these three genes, CsaMLO1, located on chromosome 1, was upregulated after PM inoculation. It co-localizes with a QTL for PM resistance previously identified. Also homologs of the susceptibility genes PMR4 and PMR5 are located at this QTL. The second MLO-like gene from Clade V (CsaMLO8) resides in a recessively inherited major QTL for PM resistance at the bottom of chromosome 5, together with a PMR6-like gene. Two major QTL for DM recessive resistance at the top of chromosome 5 co-localize with CsaDMR6-2, which is homologous to the DMR6 susceptibility gene in Arabidopsis. This study has identified several candidate genes for susceptibility to PM and DM in cucumber that may explain QTL for recessively inherited resistance, reported earlier.