豌豆品系X9002抗白粉病基因鉴定

白粉病是豌豆的主要病害之一,在全球范围内引起严重经济损失。防治豌豆白粉病最有效、经济和环境友好的方法是利用抗病品种。迄今,2个隐性抗白粉病基因er1、er2和一个显性抗白粉病基因Er3已在豌豆中被鉴定,其中er1基因在世界上被广泛应用于抗病品种培育。er1基因隶属MLO基因家族,其抗性由豌豆Ps MLO1基因座位功能丧失产生。X9002是甘肃省农业科学院培育的一个半无叶(afila)抗白粉病豌豆品系。本研究对X9002抗白粉病基因进行鉴定,开发用于抗白粉病基因选择的分子标记。遗传分析表明X9002对白粉病抗性由1个隐性单基因控制,SSR标记将该基因定位到豌豆第VI连锁群er1座位区域,标记AD60和c5DNAmet与其连锁。Ps MLO1基因序列分析发现,X9002存在一个未知大小和身份的片段插入,该类型突变也发生在含有er1-2等位基因的豌豆品种Stratagem和Franklin,表明X9002抗白粉病基因为er1-2。一个鉴定er1-2等位基因的功能标记Ps MLO1-650被开发,该标记为互引相标记,仅在感病植株中扩增,可以有效用于分子辅助选择。     

新疆小麦Psy-A1、Ppo-A1、Ppo-D1、TaLox-B1等位变异对面粉色泽的影响

利用已开发的面粉色泽相关性状基因的分子标记,检测了182份新疆小麦品种(系)的Psy-A1、Ppo-A1、Ppo-D1、Ta Lox-B1等位变异,并结合表型鉴定结果,分析不同等位变异对面粉色泽的影响。结果表明,单基因等位变异对面粉色泽的影响不同,其中4个基因等位变异L*值的差异均不显著;对a*值的效应,Psy-A1a高于Psy-A1b(P0.01),Ppo-A1b高于Ppo-A1a(P0.05),Ta Lox-B1a高于Ta Lox-B1b(P0.05);Psy-A1a基因型的b*值高于Psy-A1b基因型(P0.01);Psy-A1a基因型的Wht值低于Psy-A1b基因型(P0.01)。说明Psy-A1是影响面粉色泽(红度、黄度和白度)的重要基因,而Ppo-A1和Ta Lox-B1基因的等位变异只对面粉红度有显著影响。4个检测基因共有12种等位变异组合,对a*、b*和Wht值有显著效应(P0.01),但对L*值影响不显著(P0.05);Psy-A1b/Ppo-A1a/Ppo-D1b/Ta Lox-B1b组合具有最高的Wht值和最低的a*、b*值,Psy-A1a/Ppo-A1a/Ppo-D1b/Ta Lox-B1a组合具有最低的Wht值和最高的a*、b*值。182份品种的Wht值平均为86.86,其中审定品种平均为86.87,冬小麦品种为86.42,春小麦品种为87.32。青春5号具有优良的基因型和较高的面粉白度,应加强利用。总体来看,改良新疆小麦面粉的白度,应重点加强对Psy-A1基因的选择,提高Psy-A1b比例。     

Functional diversity of microbial communities in the mixed boreal plain forest of central Canada

This study was designed to examine whether or not specific tree species (Picea glauca, Picea mariana, Pinus banksiana, Populus tremuloides), their post-fire stand age, or their position in a successional pathway had any significant effect on the functional diversity of associated soil microbial communities in a typical mixed boreal forest ecosystem (Duck Mountain Provincial Forest, Manitoba, Canada). Multivariate analyses designed to identify significant biotic and/or abiotic variables associated with patterns of organic substrate utilization (assessed using the BIOLOG™ System) revealed the overall similarity in substrate utilization by the soil microbial communities. The five clusters identified differed mainly by their substrate-utilization value rather than by specific substrate utilization. Variability in community functional diversity was not strongly associated to tree species or post-fire stand age; however, redundancy analysis indicated a stronger association between substrate utilization and successional pathway and soil pH. For example, microbial communities associated with the relatively high pH soils of the P. tremuloides-P. glauca successional pathway, exhibited a greater degree of substrate utilization than those associated with the P. banksiana-P. mariana successional pathway and more acidic soils. Differences in functional diversity specific to tree species were not observed and this may have reflected the mixed nature of the forest stands and of their heterogeneous forest floor. In a densely treed, mixed boreal forest ecosystem, great overlap in tree and understory species occur making it difficult to assign a definitive microbial community to any particular tree species. The presence of P. tremuloides in all stand types and post fire stand ages has probably contributed to the large amount of overlap in utilization profiles among soil samples.     

Nitrogen availability decreases prokaryotic diversity in sandy soils

In this study, the interrelation between nitrogen availability and prokaryotic diversity are studied using a well-characterised system from a long-term field experiment on a loamy sandy soil. The prokaryotic potential functional diversity and community composition were assessed using community-level physiological profiling (CLPP), and their phylogenetic diversity was analysed using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) in combination with sequencing analysis. Highest prokaryotic potential functional diversity was measured in the control soil receiving no N fertilisation, indicating an efficient as well as versatile utilisation of the substrates in this soil. Both substrate utilisation richness and substrate utilisation evenness, the two constituents of the functional diversity, were decreased with increasing N supply. Furthermore, distinct prokaryotic community compositions were generated in N-enriched soils compared to unfertilised control soils. These differences suggest a dominance of populations adapted to utilising readily available substrates. We demonstrated that the shift in prokaryotic functional diversity was connected to a shift in the phylogenetic structure of the bacterial and archaeal communities. Taken together, our data clearly show that, for the sandy soil system, prokaryotic diversity and N availability were interrelated.     

Effects of Swertia japonica extract and its main compound swertiamarin on gastric emptying and gastrointestinal motility in mice

The Swertia japonica is used clinically as a remedy for gastrointestinal symptoms in Japan. We examined the effects of a S. japonica and swertiamarin on gastric emptying and gastrointestinal motility in atropine-, dopamine-, and 5-hydroxytryptamine (5-HT)-treated mice. All three preparations inhibited reductions in gastric emptying and gastrointestinal motility induced by dopamine (1 mg/kg, intraperitoneal injection, ip). Neither the powder, swertiamarin, nor itopride had any effect on the reductions in gastric emptying and gastrointestinal motility caused by 5-HT (4 mg/kg, ip). These findings suggest that the powder and swertiamarin stimulate gastric emptying and gastrointestinal motility by inhibiting the dopamine D₂ receptor.     

Canopy cover and groundlayer vegetation dynamics in a fire managed eastern sand savanna

Savanna vegetation is characterized by high and variable ground layer species richness regulated by functional group interactions with fire regimes and canopy cover. Frequent fire selects for C4 grasses and prairie forbs in canopy openings and C3 graminoid species and shade-adapted forbs and shrubs in canopy shade. Frequent fire also maximizes heterogeneity in partial canopy cover and species richness across the full canopy gradient. However, few studies have linked fire induced change in tree canopy cover with groundlayer vegetation dynamics in relation to this model. In 1986 and in 2007, we measured canopy cover and sampled groundlayer vegetation in 1 m² plots along 53 transects at the Tefft Savanna, a fire managed 197 ha eastern sand savanna with strong canopy cover and elevation gradients. We analyzed temporal change in canopy cover and groundlayer vegetation, correlating percent change in canopy cover with change in ground layer functional groups. After 20 years of burning at 3 fires/decade, elevation accounted for 62% of the variation in an NMS ordination of groundlayer vegetation. However, canopy cover, which averaged 24-86% in 2007, had a significant secondary effect on the ordination. Five vegetation types classified by TWINSPAN varied significantly in elevation and canopy cover. Woody vegetation comprised 8 of the 12 species with greatest niche breadths, and tended to predominant in woodland or forest, where tree cover averaged 50% or more. Forbs had greater richness in savanna, which averaged less than 30% canopy cover. The C3 sedge Carex pensylvanica was the dominant graminoid species under woodland canopy cover, and was co-dominant with the C4 grasses Andropogon scoparius and Sorghastrum nutans under savanna canopy cover. As in other savannas, N-fixing species sorted across shade and canopy openings, and heterogeneity among transects was maximized at mid-canopy cover. Over time, canopy cover decreased up to 50%, creating more open savanna conditions at mid to high elevations. This decrease was associated with a 20-100 % increase in species richness and was significantly correlated with increasing richness and cover of C4 grasses and summer flowering prairie and woodland forbs. These results support a canopy cover model of fire-maintained savanna vegetation, with greater abundance of C4 grasses and prairie forb species associated with lower canopy cover, greater heterogeneity at mid-canopy cover, and species richness maximized across the light gradient. They also indicate that decreasing canopy cover caused by repeated burning increases species richness and abundance of C4 and prairie forb species.     

城市边缘森林公园功能分区方法研究

本文在对城市边缘森林公园分区理论研究的基础上,全面考量森林公园的功能性、适宜性、生态性、多样性、开发利用的立体性等诸多特点,从理论支持到各分区方法以及方法间优劣势对比,利用数学方法和现代空间信息技术方法深化森林功能分区研究,使森林功能分区工作进一步科学化、规范化和标准化,以提升城市边缘土地利用价值,实现社会、经济、生态...     

Conservation-oriented forestry and early successional saproxylic beetles: Responses of functional groups to manipulated dead wood substrates

New conservation-oriented forestry aims to maintain intact populations of forest organisms by improving the conservation value of managed forests and providing protected areas. We tested the conservation value of treatments of dead wood for assemblages of early successional saproxylic beetles. In nine areas in northern Sweden, we selected one clear-cut, one mature managed forest and one reserve. In 2001-2002, we placed three blocks of spruce logs, each containing control, burned and shaded logs and a high stump (“snag”) at each site. Saproxylic beetles emerging from the dead wood were collected using emergence traps and beetles flying close to it were collected using flight-intercept traps. After one year of exposure, assemblage composition was examined, with respect to nutritionally-defined functional groups, red-listed species and fire-favoured species. Experimental snags were most complementary to control logs, supporting different assemblages of cambium consumers and fungivores and supporting more red-listed individuals. Burned logs supported depauperate assemblages, particularly with respect to cambium consumers, while shading of logs affected assemblages of fungivores, but only on clear-cuts. Despite containing less dead wood, managed forests provided valuable habitat, supporting similar assemblages of saproxylic beetles to reserves. Most functional groups were less abundant on clear-cuts than in older forests, but fire-favoured species were more common on clear-cuts, suggesting that clear-cuts may support assemblages of species associated with natural disturbances, if suitable substrates are available. Utilization of logs by saproxylic beetles changes over time, so long-term monitoring of our experimental logs will determine their lifetime conservation value.     

Diversity and function of decomposer fungi from a grassland soil

Despite the substantial interest to ecologists of the relationship between species diversity and ecosystem functioning, little is known about how the high species richness of decomposer (saprotrophic) fungi and their relative frequencies of occurrence influence the decomposition of organic matter. Three experiments were conducted to test the ability of culturable saprotrophic fungal isolates to utilise a range of artificial and more natural substrates that occur in organic matter, with the aims of (1) characterising the functional potential of ‘common’ and ‘occasional’ taxa in an upland grassland soil and (2) determining whether there was a high degree of apparent functional redundancy in these communities. ‘Function’ was defined as the ability of a fungal isolate to utilise broad categories of substrates (e.g. sugars, cellulose, lignin) that occur in organic matter and which change in proportion during decomposition. The terms ‘common/abundant/frequent’ and ‘occasional/infrequent’ usually referred here to the frequencies of occurrence of taxa estimated using Warcup soil plates. Accepting the difficulties of sampling fungi in soil, this appeared to be the most useful isolation method to produce a general picture of the microfungal community with an estimate of frequency of occurrence for every taxon obtained, and to provide cultures for use in function tests. The influence of this technique on the interpretation of the results is discussed.Forty-eight fungal isolates, obtained from an upland grassland in Roxburghshire, UK, were selected to cover the most ‘abundant’ taxa and a range of ‘occasionals’. Pure cultures of anamorphic fungi and members of the Zygomycota, Ascomycota and Basidiomycota were tested. Although there was apparently a high degree of functional redundancy (equivalence) in assemblages of culturable decomposer fungi, with ‘frequent’ and ‘infrequent’ taxa largely utilising the same substrates, the ‘infrequent’ taxa played important roles in decomposition. ‘Infrequent’ microfungi tested were potentially more active in decomposition than the ‘frequent’ taxa, i.e. several had a higher overall activity, were able to utilise a wider range of substrates and were more combative than the ‘abundant’ taxa. When ‘abundant’ and ‘occasional’ taxa from the same putative guild were inoculated together on grass litter, there was slight evidence of ‘positive’ indirect effects on decomposition and cellulose degradation. Some ‘negative’ effects on lignin degradation, probably as a result of combat, were observed.It is possible that the ‘occasional’ taxa increased the temporal resilience of the ecosystem process of decomposition, and were ‘waiting in the wings’ to replace the abundant taxa. Nevertheless, greater functional diversity could be associated with the uncultured taxa not studied here.     

Laccase and phosphatase activities of the dominant ectomycorrhizal types in a lowland oak forest

The year-round dynamics of laccase and acid phosphatase activities of ectomycorrhizas (EM) were monitored in an oak forest, with a microplate photometric method using individual EM root tips. Among the most frequent and abundant EM morphotypes, those of Lactarius quietus and Cortinarius anomalus showed a peak of laccase activity in spring, while those of Xerocomus chrysenteron displayed highest laccase activities in summer and autumn. In comparison, less seasonal differences were observed in EM acid phosphatase activity. This suggests that the different EM types within the EM community perform complementary functions depending on season.