白腊DREB基因克隆中简并引物的设计

根据拟南芥DREB2A基因序列进行GenBank内Blastx序列同源性查询,对其中同源性较高的25个氨基酸序列进行了分析,设计简并引物,应用RT-PCR技术克隆白腊DREB2A基因,得测长2473bp,与拟南芥DREB2A同源性为96.94%的基因片段,并在GenBank登记,注册号为AY536056。     

Gas composition and respiration of water oak (Quercus nigra L.) and green ash (Fraxinus pennsylvanica Marsh.) roots after prolonged flooding

Summary We compared the effects of 9.5 months of a continuous flooding treatment with a drained control treatment on one year-old seedlings of green ash (Fraxinus pennsylvanica Marsh.) and water oak (Quercus nigra L.), two tree species common to the bottomland-hardwood forests of eastern North America. The internal root gas composition of the more flood tolerant species, green ash, maintained higher oxygen and lower carbon dioxide concentrations under the flooding treatment than water oak. This apparently resulted in differences in rhizosphere oxidation. The amounts of Fe and Mn and the Fe/Mn ratio of the root coating extracted from trees in reduced soil conditions were much higher for the green ash than the water oak. It is argued that this reflects differences in the ability of these two species to maintain rhizosphere oxidation under prolonged periods of flooding and to prevent the accumulation of reduced potentially phytotoxic compounds. Alcohol dehydrogenase activity increased in the green ash and decreased in the water oak in the flooded treatment. This indicated that the better adapted species was able to rely upon increased anaerobic respiration in order to compensate for the decreased root oxygen supply, but the water oak was unable to maintain previous levels of respiration, probably as the result of sulfide toxicity.     

降水和温度变化对长白山地区水曲柳幼苗生长和光合参数的影响

以我国温带主要阔叶树种水曲柳幼苗为对象,在长白山自然保护区海拔740 m和1200 m布设两处试验地,分别进行增水30％(+W)、减水30％(-W)和自然降水(CK)处理试验,分析植株生长和叶片光合作用参数、可溶性蛋白和光合色素含量,以及降水和温度变化对水曲柳光合作用的影响.结果表明:温度变化对水曲柳幼苗生长和光合生理指标的影响显著,与海拔1200 m样地相比,海拔740 m样地3个处理水曲柳幼苗的基径、株高、叶片叶绿素含量和可溶性蛋白含量显著增加,胡萝卜素含量降低;叶片净光合速率、气孔导度、蒸腾速率和气孔限制值均显著升高,而胞间CO2浓度和叶片水分利用效率显著降低.水曲柳幼苗光合能力的下降归因于非气孔因素限制.降水变化对水曲柳幼苗生长及光合作用的影响均不显著.     

Phosphate Availability Alters Lateral Root Anatomy and Root Architecture of Fraxinus mandshurica Rupr. Seedlings

Plants have evolved some mechanisms to maximize the efficiency of phosphorus acquisition. Changes in root architecture are one such mechanism. When Fraxinus mandshurica Rupr. seedlings were grown under conditions of low phosphorus availability, the length of cells in the meristem zone of the lateral roots was longer, but the length of cells in the elongation and mature zones of the lateral roots was shorter,compared with seedlings grown under conditions of high phosphorus availability. The elongation rates of primary roots increased as phosphorus availability increased, but the elongation rates of the branched zones of the primary roots decreased. The number of lateral root primordia and the length of the lateral roots decreased as phosphorus availability increased. The topological index (altitude slope) decreased as phosphorus availability increased, suggesting that root architecture tended to be herringbone-like when seedlings were grown under conditions of low phosphate availability. Herringbone-like root systems exploit nutrients more efficiently, but they have higher construction costs than root systems with a branching pattem.     

Phosphate Availability Alters Lateral Root Anatomy and Root Architecture of Fraxinus mandshurica Rupr. Seedlings

Plants have evolved some mechanisms to maximize the efficiency of phosphorus acquisition.Changes in root architecture are one such mechanism. When Fraxinus mandshurica Rupr. seedlings were grown under conditions of low phosphorus availability, the length of cells in the meristem zone of the lateral roots was longer, but the length of cells in the elongation and mature zones of the lateral roots was shorter,compared with seedlings grown under conditions of high phosphorus availability. The elongation rates of primary roots increased as phosphorus availability increased, but the elongation rates of the branched zones of the primary roots decreased. The number of lateral root primordia and the length of the lateral roots decreased as phosphorus availability increased. The topological index (altitude slope) decreased as phosphorus availability increased, suggesting that root architecture tended to be herringbone-like when seedlings were grown under conditions of low phosphate availability. Herringbone-like root systems exploit nutrients more efficiently, but they have higher construction costs than root systems with a branching pattern.     

水曲柳和落叶松人工林根系分解与养分释放

采用埋袋法对水曲柳和落叶松粗根(5～10 mm)、中根(2～5 mm)、细根(＜2 mm)的分解速率及其养分释放进行了为期2年的研究.结果表明,水曲柳粗根、中根和细根年分解系数分别为0.3649、0.4381和0.2720,落叶松依次分别为0.1967、0.1955和0.2464.通过养分分析发现,根系分解过程释放大量C和养分.分解150 d后,两树种所有级别根系的可溶性糖释放均超过90%.水曲柳粗根和中根K的释放均在40%左右,细根K的释放为71%,落叶松所有级别的根系K的释放均在95%以上.在根系分解第2年,两树种粗根和中根N的释放在50%左右波动,P在40%左右波动,两树种细根N和P的释放均达到60%.因此,根系分解在C和养分循环中起重要作用,如果将其忽略,土壤有机质和养分元素的循环将会被严重低估.     

Pollen germination and pollen tube growth in Fraxinus pennsylvanica

With regard to adaptation of green ash (Fraxinus pennsylvanica Marshall) to ecological conditions in Croatia, pollen germination and pollen tube length after 2, 4 and 6 hours were examined in vitro at 10, 15, 20 and 25°C during two years 2001 and 2002. Narrow leaved ash (F. angustifolia Vahl) pollen served as a control in 2002. The year, time and temperature, and the interaction between time and temperature were significant for both germination percentage and pollen tube length. Interactions year × temperature and year × time were significant for pollen tube length only. The highest germination percentage (17.86% in 2001 and 19.40% in 2002) of green ash pollen was at 15°C after 6 hours. The pollen tube length was greatest at 20°C (393.46 μm) in 2001 and 25°C (899.50 μm) in 2002 after 6 hours. Narrow leaved ash pollen had the highest germination percentage (19.22%) at 20°C after 6 hours and was significantly reduced at 25°C. The pollen tube length was greatest at 25°C (518.90 μm) after 6 hours. It can be concluded that green ash pollen has satisfactory germination in ecological conditions in Croatia and that the optimum temperature for pollen germination is higher than 20°C.     

温度对经层积处理解除休眠的水曲柳种子萌发的影响

经层积处理解除休眠的水曲柳种子于10种不同温度条件下萌发的结果表明:变温条件下的种子萌发比恒温条件的好,最佳的变温条件为15℃/10℃,最佳的恒温条件是10℃,20℃以上的恒温会诱导种子产生二次休眠。     

Herbicide and Tillage Effects on Volunteer Vegetation Composition and Diversity During Reforestation

Fraxinus pennsylvanica (green ash) is commonly used for reforestation of agricultural lowlands in the midwestern and eastern United States. We evaluated the effects of herbicide (untreated, glyphosate, and sulfometuron methyl) and tillage (tilled and no‐till) on F. pennsylvanica success and composition of associated volunteer vegetation 3 years after the treatment applications and reforestation of a formerly cultivated field in southern Illinois. Tillage had no effect on F. pennsylvanica growth, whereas both herbicides increased all measures of tree performance. The response of associated native and non‐native species cover was affected by an interaction between the herbicide and tillage treatments. In the presence of herbicide, cover of native species was greater in the no‐till treatment, whereas non‐native cover was higher in the tillage treatment. Both native and non‐native cover were unaffected by tillage in the absence of herbicide, and there were no differences in cover among the herbicide treatments in the presence of tillage. Total diversity was higher in the tillage treatment than the no‐till treatment, and diversity was lower in the sulfometuron methyl herbicide treatment than the control and glyphosate herbicide treatment. Lower diversity in the sulfometuron methyl treatment was attributed to greater cover of a native perennial grass, Andropogon virginicus (Broomsedge), which was inversely related to total diversity. We conclude that a single glyphosate herbicide application can enhance F. pennsylvanica growth and conserve associated species diversity in this system. Furthermore, species‐specific responses of the associated vegetation should be included in management considerations, particularly if silvicultural treatments influence dominance and diversity in the establishing understory community during reforestation.     

绒毛白蜡的核型分析

应用根尖压片法对木樨科白蜡属绒毛白蜡(Fraxinus velutina)的染色体数目和核型进行了研究。结果表明:绒毛白蜡体细胞染色体数目为2n=22,核型公式为:K(2n)=22=20m+2 sm,属于"1A"类型。染色体相对长度组成为2n=22=4L+10M₂+8M₁。     

14C Translocation pathways in honeylocust and green ash: Woody plants with complex leaf forms

Long-distance transport in plants requires precise knowledge of vascular pathways, and these pathways differ among species. This study examines the ¹⁴C translocation pathways in honeylocust (Gleditsia triacanthos L.) and green ash (Fraxinus pennsylvanica Marsh.), species with compound leaves, and compares them with those of cottonwood (Populus deltoides Bartr. ex Marsh.), a species with simple leaves. The stem vasculature of honeylocust conforms to a 2/5 helical phyllotaxy and that of green ash to a decussate phyllotaxy. The plastochron is relatively long in both species – 2.5+ days in honeylocust and 4.5+ days in green ash. Consequently, the transition from upward to downward translocation from mature source leaves is abrupt and occurs close to the apex. Export of ¹⁴C from localized treatment positions within a leaf was found to vary both quantitatively and spatially. To determine export patterns, ¹⁴CO₂ was administered to either individual leaflets of once-pinnate or pinnae of bipinnate leaves of honeylocust, and to either individual veins of simple or leaflets of compound leaves of green ash. Transections of either the petiole or rachis base were then examined for ¹⁴C by micro-autoradiography. In all cases, as treatment positions advanced acropetally in the leaves, the bundles translocating ¹⁴C were situated more dorsally in the basal petiole and rachis vasculatures. ¹⁴C was confined to the right side of the vasculature when structures on the right side of a leaf were treated. Compound leaves of both species mature acropetally. Thus, mature basal pinnae of honeylocust and basal leaflets of green ash translocate acropetally to younger leaf parts that are still rapidly expanding. All translocation pathways, both in the stem and leaf, conformed with vascular organization previously determined by anatomical analyses.     

低温预处理对水曲柳体细胞胚胎发生的影响

用4℃低温预处理未成熟的水曲柳种子0-30d,取出种子内的合子胚为外植体诱导体胚发生,研究低温预处理影响体胚发生的结果表明：低温预处理过的外植体其体胚发生总数和子叶胚发生数均低于未作低温预处理的;随着预处理时间的延长,畸形胚发生数和发生比率与总的体胚发生数和发生率的变化趋势基本相同;处理20d的正常胚发生数和发生比率的绝对数虽然很低,但远高于不作低温预处理的。说明4℃低温预处理对水曲柳体胚发生没有促进作用,对畸形胚的发生也不能控制,总的来讲,适当的低温处理有一定的改善正常体胚发生的潜力。     

Differentiation of circular vessels in isolated segments of Fraxinus excelsior

The differentiation of circular vessels was studied in stem segments which had passed winter dormancy and were stimulated by application of auxin in vitro. The circular vessels differentiated near the basal end of internodes. The prevailing form of circular vessels was a pair of cells connected by two perforations. Two-cell vessels never had only one perforation. The occurrence of two perforations strongly supports the view that auxin flux is a stimulus for vessel differentiation and not the very presence or concentration of auxin; the circular vessels developed as a results of a circular flux. In general, the circular vessels appeared in contact with rays. Their formation was delayed in comparison with that of normal vessels.     

Execution of the auxin replacement apical dominance experiment in temperate woody species

The classic Thimann-Skoog or auxin replacement apical dominance test of exogenous auxin repression of lateral bud outgrowth was successfully executed in both seedlings and older trees of white ash, green ash, and red oak under the following conditions: (1) decapitation of a twig apex and auxin replacement were carried out during spring flush, (2) the decapitation was in the previous season's overwintered wood, and (3) the point of decapitation was below the upper large irrepressible lateral buds but above the lower repressible lateral buds. Although it has been suggested that neither auxin, the terminal bud, nor apical dominance have control over the outgrowth of the irrepressible buds during spring flush, there is evidence in the present study that indicates that such control over the repressible buds exists. In seedlings, second-order branching, which resulted from decapitation of elongating current shoots, was also inhibited by exogenous auxin in the three species. Hence, the auxin replacement experiments did work on year-old proleptic buds (of branches of older trees) that would have entered the bud bank and also on current buds of seedlings. Cytokinin treatments were ineffectual in promoting bud growth.     

水曲柳种子次生休眠的预防和解除

以解除休眠和经高温诱导产生次生休眠的水曲柳种子为材料,探讨预防和解除水曲柳种子次生休眠的方法。结果表明：GA3和乙烯利不能阻止已解除休眠水曲柳种子在25℃下萌发时诱导的次生休眠。干燥和短时间低温解除水曲柳种子次生休眠的效果不明显,较长时间（大于2周）的低温对解除水曲柳种子的次生休眠有一定的效果。综合来看,10^-3mol·L^-1的乙烯利或GA4＋7解除水曲柳种子次生休眠的效果较好。     

Maternal inheritance of a chloroplast microsatellite marker in controlled hybrids between Fraxinus excelsior and Fraxinus angustifolia

Restriction fragment length polymorphism, polymerase chain reaction-restriction fragment length polymorphism and simple sequence repeat (SSR or microsatellites) analyses were performed to detect chloroplast DNA polymorphisms between two ash species, Fraxinus excelsior and F. angustifolia. Only one SSR locus was found to be polymorphic, confirming the very close relatedness of these species. Inheritance of this marker was studied in hybrids obtained from controlled crosses between the two tree species. Results indicated, for the first time in Oleaceae, that chloroplasts are maternally inherited. This chloroplast SSR marker is now used concomitantly with nuclear markers to analyse ash populations in sympatric areas.     

白蜡属种间杂交子代木质素含量变异及FmPAL核苷酸多态性关联分析

研究水曲柳（Fraxinus mandshurica）×大叶白蜡（Fraxinus rhynchophylla）、水曲柳×小叶白蜡（Fraxinus sogdiana）和水曲柳×绒毛白蜡（Fraxinus velutina）的3个杂交组合与母本自由授粉子代木质素含量的遗传变异及FmPAL核苷酸多态性相关性,为水曲柳遗传育种和定向改良奠定基础。以东北林业大学帽儿山林场白蜡属种间杂交组合及母本自由授粉子代共176个无性系的水曲柳当年新生枝为材料,测定木质素的含量,进行木质素含量差异、变异参数及均值比较分析,并对木质素及其合成相关基因PAL进行分子水平的联合分析。结果表明：白蜡属各杂交组合间木质素含量差异极显著,各杂交组的木质素含量均与母本自由授粉子代水曲柳差异显著。其中大多数杂交子代水曲柳的木质素含量高于母本水曲柳木质素平均含量。本研究中的水曲柳群体的PAL基因单倍体多样性值达到了0.999 7,属高水平,证实了FmPAL基因具有较高的变异,且存在3个单核苷酸多态性（SNP）位点与木质素含量显著相关。主要结论：水曲柳各杂交组合的木质素含量存在显著性差异,FmPAL基因中SNP位点与木质素含量显著相关。