菠萝叶片总RNA提取方法的比较

为了探究不同提取方法对菠萝叶片组织总RNA提取质量的影响,以‘台农16号’菠萝品种的叶片为材料,采用改良Tirs-硼酸法、改良SDS法、试剂盒法提取菠萝叶片组织总RNA,并对提取的总RNA浓度、OD260/OD230、OD260/OD280、琼脂糖电泳结果进行了比较分析。结果表明:改良Tris-硼酸法和试剂盒法能较好地去除菠萝叶片组织的多糖、皂苷元、蛋白质以及纤维等次生代谢物质,OD260/OD230大于2.000,OD260/OD280在1.900~2.100之间。改良SDS法提取总RNA产率最高,达到290.9μg/m L。试剂盒法提取总RNA产率为30.1μg/m L,远小于其它2种提取方法所得总RNA产率。改良Tris-硼酸法所得电泳图谱条带完整度最好。比较分析3种提取总RNA方法的结果,以改良Tris-硼酸法提取总RNA的效果较理想,可满足后续研究工作的需要。     

木本植物根系总RNA提取方法的比较和分析

以杂种马褂木不定根和杨树、柳树、柽柳根系组织为材料,比较异硫氰酸胍法、Tiangen试剂盒、CTAB改良法、Trizol法和改良Trizol法提取总RNA的效果。结果表明,改良Trizol法通过在离心后的匀浆上清液中加入低浓度的无水乙醇以及结合后续的高盐溶液,能有效去除多糖,提取的RNA中28S rRNA亮度约为18S rRNA的两倍,OD260/OD280值介于1.7～2.1之间,各林木树种根系组织RNA得率均大于150μg/g,而且整个提取时间只要2～3 h。表明改良Trizol法方便、快捷、高效,完全适用于林木树种根系组织RNA的提取。     

适于转录组测序的枣不同器官总RNA提取方法筛选

为获得适用于转录组测序的枣花、结果枝和果实的总RNA提取方法,以中秋酥脆枣为材料,比较分析了Ambiogen和Autolab 2种总RNA提取试剂盒和基于Autolab试剂盒改良的CTAB法的总RNA的提取效果。结果表明:3种方法提取RNA的OD260/OD280差别不大,但用2种试剂盒提取的RNA有降解,其中Ambiogen试剂盒提取的花、结果枝和果实3个器官的RNA质量浓度分别为126、284和222 ng/μL;Autolab试剂盒提取的RNA质量浓度分别为307、402和266 ng/μL;基于Autolab试剂盒改良的CTAB法提取的RNA质量浓度分别为401、417和296 ng/μL。与2种试剂盒相比,基于Autolab试剂盒改良的CTAB法提取出来的RNA完整性好、纯度和浓度高,能够满足转录组测序的要求。     

几种提取杜仲RNA方法的比较

杜仲富含酚类、多糖、蛋白、杜仲胶等代谢物质,用普通方法提取杜仲RNA时很难将其去除,比较研究了Trizol、CTAB和热硼酸盐3种方法,发现改进的CTAB法和热硼酸盐法均能从杜仲中提取纯度较高的RNA,热硼盐法分离效果最好,凝胶电泳显示条带清晰完整,分光光度计检测OD260/OD280=1.92.用该方法提取的杜仲RNA可以进行RT-PCR、Northern-blot、RACE等分子生物研究.     

不同化学类型樟树叶片总RNA提取方法比较

采用SDS/酸酚法、Trizol试剂法、常规CTAB法及改良的CTAB法,分别提取5种化学类型樟树叶片总RNA,并对提取效果进行了比较分析。结果表明:Trizol法难以提取樟树叶片总RNA,得率很低;SDS/酸酚法和常规CTAB法得到的RNA存在DNA污染,富含蛋白、多糖、多酚等杂质;这3种方法均不适于富含多糖多酚类物质的樟树叶片总RNA的提取。改良的CTAB法能够提取得到樟树5种化学类型叶片总RNA,且在操作过程中,异樟比油樟和脑樟更易提取。此法能有效去除多糖和蛋白,提取得到的RNA 28S和18S rRNA条带清晰,OD260/OD280值为2.0左右,平均产率分别为115.8μg/g FW。经RT-PCR检测,所得总RNA质量高、完整性好、成功率高,可以满足下一步实验的要求,可作为樟树叶片总RNA提取的首选方法。     

小佛肚竹和螺节竹总RNA的提取

首次提出了一种适用于小佛肚竹(Bambusa ventricosa)和螺节竹(Pleioblastus gramineus)等竹类植物总RNA提取方法.用该方法提取叶片和笋尖的总RNA具有正常的光谱吸收,OD260/OD280比值为1.96～2.0,OD260/OD230比值为2.96～4.11;琼脂糖电泳后,28 SRNA的亮度基本为18 SRNA的亮度的2倍;这说明提取的RNA很完整,未降解,质量高.同时该方法操作简便、无DNA污染,且产率高;提取的RNA可用于RT-PCR、Northern杂交、cDNA文库的构建等.     

山核桃花芽总RNA提取方法研究

以山核桃的花芽为材料,利用改良CTAB法、异硫氰酸胍法和改良热酚法提取其总RNA,并对RNA产率、纯度、电泳图谱和RT-PCR进行分析,结果表明:改良CTAB法明显优于其它两种提取方法,用它提取的28S rRNA、18S rRNA条带清晰、稳定,无降解,OD260/OD280值保持在1.9～2.0,产率相对较高;经RT-PCR检测发现,改良CTAB提取的RNA能被成花基因特异引物扩增出清晰的条带,说明该法完全适合于山核桃花芽总RNA的提取,并可用于Northern杂交、cDNA文库构建等分子生物学操作.     

草珊瑚叶片总RNA提取方法及效果的比较研究

采用CTAB法、CTAB-Li Cl法、CTAB-Trizol法、Trizol法、天根RNA提取试剂盒及百泰克RNA提取试剂盒提取草珊瑚(Sarcandra glabra)叶片总RNA,并通过微量紫外分光光度计、电泳检测等对提取的结果进行了分析比较。结果表明:CTAB-LiCl法和天根RNA提取试剂盒比较适合提取草珊瑚叶片的总RNA。这两种方法提取的总RNA的完整性和纯度较高,无明显的蛋白质及其他杂质污染,OD_(260)/OD_(280)的值在1.9~2.1,OD260/OD230在2.0~2.4。获得质量高、完整性好、纯度高的总RNA,为后续构建cDNA文库以及相关基因的克隆提供了试验基础。     

芒果属植物叶绿体DNA提取方法的研究

为了探究不同提取方法对芒果属植物叶绿体DNA提取质量的影响,以芒果和扁桃的成熟叶片为材料,比较植物叶绿体DNAout试剂盒法和高盐-低p H法分离叶绿体及提取叶绿体DNA效果。结果表明:叶绿体DNAout试剂盒法能够较好地去除蛋白质、酚类、多糖等代谢物质,OD260/OD230大于2.000,OD260/OD280在1.800~1.900之间。高盐-低p H法提取叶绿体DNA产率高达75.8 ng/μL,远大于叶绿体DNAout试剂盒法提取叶绿体DNA最高产率42.8 ng/μL,2种方法所得模板电泳图和SSR标记图谱谱带完整性皆好。显微镜下观察叶绿体,2种方法都可以得到杂质少、背景清晰的叶绿体显微成像效果,但高盐-低p H法提取的叶绿体细胞器密度更高。2种方法获得的叶绿体DNA均可满足后续研究工作的需要。     

华南五针松成熟针叶基因组DNA的提取方法

在传统CTAB方法的基础上进行改良,建立了适用于华南五针松成熟针叶DNA提取的CTAB法,该方法具有稳定、操作简单、可靠等特点。使用该方法对不同地理分布的华南五针松成熟针叶进行基因组DNA的提取,经紫外分光光度计检测其A260/A280在1.60～1.78之间,OD260/OD230比值介于2.0～2.3之间,无降解现象,RNA去除干净。经ISSR-PCR分析,条带清晰,完全能够达到分子标记的操作要求。     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.