Pollen development and floral morphology of Populus pseudo-simonii

Pollen development and floral morphology of Populus pseudo-simonii were investigated by stain-squashing and anatomical techniques. It took approximately 16 days for the pollen to develop from pollen mother cells to mature pollen in the greenhouse. Meiosis of pollen mother cells was regularly applied and completed by a process of simultaneous cytokinesis. Pollen development was considerably asynchronous. The meiotic division was initiated at the bulgy middle position of the flower bud and proceeded towards t...     

Comparative microsporogenesis and flower development in <Emphasis Type="Italic">Eucalyptus urophylla</Emphasis> × <Emphasis Type="Italic">E. grandis</Emphasis>

Microsporogenesis and flower development in Eucalyptus urophylla × E. grandis were examined using chromosome tableting to provide a method to predict the meiotic stages in this species. Although microsporogenesis was normal, cytokinesis during meiosis of pollen mother cells occurred simultaneously, with strong asynchronism observed in the two different lengths of stamens in a flower bud. In a single flower, the developmental period of microsporogenesis in anthers on the longer stamens was always ahead of those on the shorter stamens. Flower development was also asynchronous at different locations on a branch. Flower buds on the upper side of the branch were larger in diameter than those on the lower side. In addition, a correlation was observed between microsporogenesis development and flower bud diameter growth. The pachytene stage was first observed when the diameter of the flower buds increased to 3.0 mm, and the majority of the meiotic stages were observed when bud diameters ranged from 3.5 to 5.0 mm. This study showed that the developmental stages of microsporogenesis in Eucalyptus urophylla × E. grandis could be distinguished readily, which may be applicable to future breeding studies.     

Inhibition of flower bud formation inBetula platyphylla andBetula pendula by gibberellin (GA3) application

Birch (Betula) trees produce a large amount of pollen, which is a cause of serious pollinosis. To control the pollen scattering, we examined the inhibitory effect of gibberellin (GA₃) on flower bud formation of birch. Field-grown trees ofBetula pendula, nine years of age, were treated with a foliar spray of GA₃ (1, 10, and 100 mg L⁻¹),Betula platyphylla trees, 17–23 years of age, were treated with a stem injection of GA₃ (5, 50, and 500 mg per plant) in June or July, 1998. Male flower buds were not observed at the top of new shoots in June, but were observed in July. The number of inflorescence that emerged from randomly sampled branches was counted the next spring. The foliar spray of GA₃ in June at the dose of 10 or 100 mg L⁻¹ decreased the number of inflorescence. Stem injection in June at a dose higher than 50 mg per plant completely inhibited flower bud formation, although it increased bud mortality in some trees. The most effective dose of GA₃ for stem injection to inhibit flower bud formation was between 0.04 and 0.44 mg per cm² of stem cross-section area at breast height. These results indicate that GA₃ applied during the period of floral differentiation markedly inhibits flower bud formation in birch.     

山鸡椒雌花花芽分化形态特征及碳氮营养变化

目的]了解和掌握山鸡椒雌花花芽分化的形态特征及碳氮营养规律,为山鸡椒人工栽培及杂交育种提供参考依据。[方法]采用石蜡切片法观察山鸡椒雌花花芽分化的组织解剖结构,采用生理试剂盒-分光光度法测定雌花不同分化时期的可溶性糖、淀粉、可溶性蛋白、碳氮比等碳氮营养指标。[结果]表明:(1)山鸡椒雌花花芽分化经过未分化期—花序原基分化期—苞片原基分化期—花原基分化期—花器官分化期5个时期。(2)叶片可溶性糖含量随着花芽分化的发展呈不断升高的趋势,最高可达65.07 mg·g~(-1)。叶片淀粉含量随着分化时期的推进呈先升后降的趋势,其最高值出现在苞片原基分化期,达到81.30 mg·g~(-1),最低值出现在花器官分化期,为52.19 mg·g~(-1)。(3)叶片可溶性蛋白含量在花芽前3个分化期呈持续下降趋势,从61.32 mg·g~(-1)下降到52.48 mg·g~(-1),之后基本保持稳定。叶片中的碳氮比在花芽前3个分化期呈持续上升趋势,从1.49上升至2.61,之后基本维持在较高水平。[结论]山鸡椒雌花花芽分化的内部形态特征与雄花基本一致,雌花花芽分化分为5个时期。山鸡椒雌花花芽分化过程中,叶片中可溶性糖不断升高,而可溶性蛋白下降明显,碳氮比升高且保持在较高水平。     

Comparative microsporogenesis and flower development in Eucalyptus urophylla × E. grandis

Microsporogenesis and flower development in Eucalyptus urophylla 9 E. grandis were examined using chromosome tableting to provide a method to predict the meiotic stages in this species. Although microsporogenesis was normal, cytokinesis during meiosis of pollen mother cells occurred simultaneously, with strong asynchronism observed in the two different lengths of stamens in a flower bud. In a single flower, the developmental period of microsporogenesis in anthers on the longer stamens was always ahead of those on the shorter stamens. Flower development was also asynchronous at different locations on a branch. Flower buds on the upper side of the branch were larger in diameter than those on the lower side. In addition,a correlation was observed between microsporogenesisdevelopment and flower bud diameter growth. The pachytene stage was first observed when the diameter of the flower buds increased to 3.0 mm, and the majority of the meiotic stages were observed when bud diameters ranged from 3.5 to5.0 mm. This study showed that the developmental stages of microsporogenesis in Eucalyptus urophylla 9 E. grandis could be distinguished readily, which may be applicable to future breeding studies.     

Meiotic chromosome preparation techniques of pollen mother cells for laser micro-dissection in <Emphasis Type="Italic">Populus</Emphasis> spp.

In order to isolate meiotic chromosomes of Populus species meiotic chromosome preparation techniques of pollen mother cells for laser micro-dissection were studied. Pollen mother cells at diakinesis of Populus canadensis Moench were used as samples. Two methods were used to prepare meiotic chromosomes: in the first, cell suspensions were dropped on polyethylene-naphthalate or polyester membrane slides which had just been incubated at –20°C; in the second method, cell suspensions were also dropped on polyethylene-naphthalate or polyester membrane slides, but spread with the aid of high temperatures. The cells did not completely spread by the first method and chromosomes at diakinesis could not be individually distinguished. In contrast, well-spread diakinesis chromosomes were obtained by the second method, where chromosomes, connected with their nucleolus, were successfully isolated with the laser micro-dissection system. As well, we discuss the prospect of applications of laser micro-dissection in cytogenetics and molecular genetics in Populus species.     

Study of sugi (Cryptomeria japonica D. Don) with male-sterility gene using CAPS markers

The frequency of open-pollinated male-sterile seedlings from a male-sterile mother tree in Cryptomeria japonica D. Don was determined in 765 open-pollinated seedlings. Pollen was not formed by 29 out of the 765 seedlings. To find pollen donor candidates for 29 male-sterile seedlings, a male-sterile tree was crossed with five individuals in the neighborhood of the mother tree. Analysis of microspores in male flowers of F₁ seedlings revealed that one of the five individuals had a heterozygous male-sterility gene. Paternity tests were conducted on the 29 male-sterile seedlings using eight kinds of CAPS markers in C. japonica. The pollen parents of 29 male-sterile seedlings were not only a tree in the neighborhood of the mother tree, but also other trees. Since it was found that the pollen parents of four of the male-sterile seedlings were not in the study plot, it was inferred that C. japonica trees that possess the male-sterility gene grow in other places and may be widely distributed.     

Pollen dispersal in a hinoki (Chamaecyparis obtusa) seed orchard detected using a chloroplast DNA marker

Pollen dispersal was estimated in two test plots in a hinoki (Chamaecyparis obtusa) seed orchard using a chloroplast DNA marker, the spacer region between thetrnD andtrnY genes, and SSCP (single strand conformation polymorphism). In Plot 1, 2,020 seeds from 40 trees within 30 m of the marker tree were analyzed using the PCR-SSCP method. In Plot 2, 1,850 seeds from 37 trees were analyzed in the same manner. The results revealed that the maximum pollen dispersal distance in the two plots exceeded 25 m. Pollen dispersal appeared to be inversely proportional to the distance from the marker tree. The effective pollen dispersal was suggested to be less than about 20 m in a mature hinoki seed orchard. Adjacent trees had an excessive influence when the pollen density was increased by artificial flower stimulation. Therefore, it was suggested that seed production better resembles ideal random mating when carried out as naturally as possible. In conclusion, the SSCP chloroplast DNA marker was a useful tool for amassing basic information on pollen management in seed orchards of coniferous species.     

AcCBF1转录因子沉默对低温胁迫下扁桃花器官的影响

为了探明AcCBF1基因沉默对‘纸皮’扁桃花器官的影响,以了解CBF转录因子在扁桃花器官发育中的功能,采用病毒诱导的基因沉默(VIGS)技术,以采用农杆菌侵染方法获得的含有pTRV2-AcCBF11、pTRV2-AcCBF12、pTRV2-AcCBF13片段的扁桃AcCBF1基因沉默枝条为试验材料,以常温和低温处理后的自然生长扁桃枝条为对照,观测低温处理后花器官表型指标变化,并对单花药花粉量、花粉活力以及花粉扫描电镜指标结果进行分析。结果表明:低温处理降低了对照组的单花药花粉量和花粉活力,但对花器官指标影响不显著。沉默后的AcCBF12片段和AcCBF13片段显著降低了花粉量与花粉活力,沉默花器官指标效果明显。花粉粒大小无显著变化,花粉纹饰存在一定差异。AcCBF11片段沉默效果不明显。AcCBF12片段和AcCBF13片段影响扁桃花器官表型指标的变化,如花瓣、花冠、花萼、花药、花粉形态、花粉量、花粉活力等,预测CBF转录因子可能在花器官指标发育中发挥着重要功能。     

麻疯树BRI1基因的鉴定及其在不同发育时期花蕾中的表达分析

[目的]研究油菜素内酯受体BRI1的同源基因(JcBRI1)在麻疯树花发育过程中的作用。[方法]利用RT-PCR技术克隆JcBRI1基因的CDS,以pET-30a(+)质粒为框架构建原核表达载体转化至大肠杆菌进行诱导表达,随后利用LC-MS/MS对表达产物进行质谱鉴定,并以氨基酸序列为基础分析JcBRI1蛋白质结构。利用荧光定量PCR分析麻疯树JcBRI1基因在雌雄花发育的关键时期的表达水平,初步确定其在麻疯树花发育过程中的表达模式。[结果]克隆获得了JcBRI1基因的CDS,长度为3 591 bp。SDS-PAGE检测结果表明:JcBRI1基因在大肠杆菌BL21(DE3)和Rosetta(DE3)中均能表达,但在低温环境的表达量更高。原核表达产物的LC-MS/MS鉴定结果表明:JcBRI1氨基酸序列与预期的一致,JcBRI1基因的表达产物为麻疯树BRI1蛋白。对JcBRI1在麻疯树花器官不同发育时期的表达水平进行检测分析,结果表明:JcBRI1基因的表达量在雌花发育的第一个时期即大孢子母细胞时期就达到了最高值,在随后几个时期持续下调;然而,其在雄花各个时期的表达量并无明显差异,表明其很有可能参与了麻疯树雌花大孢子母细胞发育过程。[结论]麻疯树JcBRI1基因为LRR-RLKs家族成员BRI1的同源基因,很有可能参与麻疯树雌花大孢子母细胞的发育过程,至于JcBRI1在麻疯树大孢子母细胞发育过程中的具体作用机制还需进一步研究。     

Overhead irrigation increased winter chilling and floral bud production in Eucalyptus nitens

Eucalyptus nitens requires a sufficiently cold winter to produce flower buds. In areas in South Africa where E. nitens commercial plantations as well as breeding and production seed orchards are located, winter chilling is often insufficient for floral bud initiation. Hence, under such conditions, E. nitens floral bud and seed crops are poor and inconsistent. The local industry is almost entirely dependent on paclobutrazol (PBZ) applications for encouraging flowering in E. nitens seed orchards. Between 2008 and 2010, an experiment was conducted to investigate the potential of overhead irrigation (sprinkling) as a means of supplementing winter chilling to improve floral bud production in E. nitens. The treatments included three levels of sprinkling (nil, 10 weeks and 16 weeks duration), two levels of PBZ (nil, 0.025 g a.i. per mm basal stem circumference) and two grafted clones (prolific flowerer and shy-flowerer). Sprinkling reduced E. nitens daytime bud temperatures by as much as 16.2 °C on warm, dry winter days. In 2009 (cold winter) and 2010 (warm winter), sprinkling increased chilling accumulation by 44% and 72% (nil versus maximum sprinkling), respectively. In 2009, in the absence of PBZ, sprinkling resulted in a higher percentage of trees of either clone producing umbels (flower buds) compared with the control. In the warmer 2010 winter, sprinkling again increased flowering, with the number of flowering shoots and umbels per tree being significantly higher than the control at p < 0.05. In both 2009 and 2010, PBZ showed a strong additive effect to winter chilling on E. nitens floral bud production. The E. nitens clone × chilling × PBZ flowering interaction was complex and warrants more detailed investigation in future. Overhead sprinkling offers a practical method of supplementing winter chilling and improving floral bud production in high-chill-requiring temperate eucalypt species such as E. nitens.     

A MADS-box gene of Populus deltoides expressed during flower development and in vegetative organs

A MADS-box gene (PdPI) was isolated from a cDNA library constructed from male flower buds of Populus deltoides Bartr. ex Marsh. According to an analysis of genomic DNA structure and putative protein structure, and a phylogenetic study, PdPI is an ortholog of the Arabidopsis PI gene. Relative-quantitative real-time polymerase chain reaction analysis showed that PdPI has a broader expression pattern than PI in Arabidopsis. PdPI was strongly expressed in floral buds and roots and weakly expressed in immature xylem, leaves and apical buds of the male P. deltoides tree. In male inflorescences, PdPI expression was abundant in the perianth and anther, and weak in the peduncle and mature pollen. The large differences in PdPI expression at various phases of male floral bud development were closely related to the development of flower organs (perianth and stamen) and pollen. PdPI was also expressed in female inflorescences. Our results suggest that PdPI has multiple functions in the development of P. deltoides.     

灰木莲花期物侯观测及生殖构件分布

[目的]为了解灰木莲引种到广西凭祥地区花期物侯及生殖构件分布状况,为其在引种地败育机制的研究奠定基础。[方法]选择中国林科院热林中心树木园、白云实验场、伏波实验场的灰木莲人工林为观测对象,参考Dafni方法,从林分到单株水平调查研究灰木莲在广西凭祥地区的花期物候、开花特征及生殖构件分布,跟踪观察单花开花动态进程,统计花部组件大小、数量及位置等特征。[结果]表明:灰木莲花为子房上位的两性花,雄蕊群着生于雌蕊群下部,雄蕊短小,其高度仅达到雌蕊群下缘;灰木莲花芽到开花过程可分为混合芽阶段、花芽阶段、花蕾露白阶段、白蕾阶段、展花阶段、花瓣脱落阶段6个阶段,花被片展开存在二次开合现象;在适生区,灰木莲开花特征稳定,开花强度中等,不同海拔高度灰木莲林分的花期物侯存在差异,林分的生殖构件在林内、林缘分布差异显著,且生殖构件的败育率极高。[结论]灰木莲引种到广西凭祥地区花期物侯稳定,开花同步性较高,但是花果转化率极低。     

A tool for identifying potential Eucalyptus nitens seed orchard sites based on climate and topography

Shy seed production in orchards of Eucalyptus nitens is a major barrier to the deployment of genetic gain in South African plantations. A machine learning method was used to identify optimal sites for the establishment of E. nitens seed orchards within the plantation forestry landscape of the summer rainfall region of South Africa. The ensemble classifier random forests (RF) was used to identify the environmental factors conducive to E. nitens floral bud production, and, based on these, build a predictive model deployable to the plantation forestry landscape for identifying suitable areas for E. nitens seed orchards. The RF model predicted site suitability likelihood for floral bud production with a high level of accuracy (area under the receiver operating characteristic curve = 0.83). Within the climatically optimal range for growing E. nitens, flower bud production was more abundant and consistent on cold slopes, i.e. sites experiencing lower minimum air temperatures during spring and autumn. The model was applied to the commercial plantation forestry landscape for the purpose of indicating sites climatically optimal for floral bud production in E. nitens and the establishment of breeding and seed production orchards of the same species.     

Using flower strips to promote green lacewings to control cabbage insect pests

Habitat management improves biological control by increasing the abundance and fitness of natural enemies through the provision of floral resources along field edges or between crops. Among the natural enemies reliant on flower resources, green lacewings often stand out due to their abundance, predation capacity and polyphagy. We evaluated the impact of tailored flower strips on the enhancement of natural enemies, especially green lacewings, in three organic cabbage (Brassica oleracea) farms in Southern Sweden. Insects were sampled from the flower strips, and cabbage pests and predators were visually recorded in the crop. In a laboratory assay, the pollen feeding preferences of Chrysoperla carnea (Stephens, 1836) were evaluated in a dual-choice test. The pollen consumed by the Chrysopidae was extracted from laboratory and field specimens, then quantified and identified. Flower strips were found to attract predators and parasitoids, whose abundance increased as flowers bloomed. Cabbage plants next to the flower strips showed lower pest infestation as compared to cabbage plant control, although no significant differences were observed in the number of predators. Chrysopidae used flower strips as feeding, reproduction and shelter sites and mainly consumed pollen from Phacelia tanacetifolia Benth. Under laboratory conditions, C. carnea showed a preference for P. tanacetifolia and Coriandrum sativum L. pollen over Borago officinalis L. and Fagopyrum esculentum Moench. We show that tailored flower strips could be an efficient tool for enhancing beneficial arthropods and should be considered in integrated pest management for cabbage crops.

     

澳洲坚果花芽分化的形态学观察

据对澳洲坚果的花芽分化形态学观察结果:花芽分化初期正常,小花分化是从外往内。其生殖器官属于适于异花传粉的雌雄蕊异长型;花芽分化过程中在花托中部、花被、药隔周围等均出现了大量的后含物;花序发育过程中出现了大量脱落的小花;花粉囊结构正常,花粉母细胞为连续性减数分裂;四分体解体后绝大多数单核花粉粒异常,花粉囊内仅约1/9花粉粒正常发育,另有约1/9花粉粒死亡;剩余的7/9花粉粒均为残片,残片周围均环有胼胝质壁。后期花粉囊有大量中空败育的花粉粒,从形态解剖学的角度来看,这是澳洲坚果结实率低的最重要的原因之一。     

Induction of unreduced megaspores with high temperature during megasporogenesis in <Emphasis Type="Italic">Populus</Emphasis>

Introduction  

Triploid breeding is one of the most powerful approaches for improvement of the genus Populus L. Pollination with artificial unreduced (2n) pollen was inefficiency, owing to weak competition of 2n pollen. To induce 2n megaspores and improve the efficiency of triploid production, female buds of Populus pseudo-simonii × Populus nigra ‘Zheyin3#’ were exposed to high temperature during megasporogenesis.     

核桃雌花分化的内源激素模式

在雌花芽分化阶段,应用气液色谱-电子捕获或氢焰离子技术,对3年生早、晚实类型核桃实生幼树分别检测了雌花芽和营养芽中内源细胞分裂素、赤霉素、生长素和脱落酸的水平。依次用它们的相对量来表示,两种芽中激素水平的变化可以简单描述如下: 雌花芽:(+,-,-,-); 营养芽:(-,+,+,+)。这个模式揭示:(1)雌花芽分化是四种激素作用于芽分生组织的某一特定平衡的结果;(2)细胞分裂素与赤霉素的比值与这些组织形成雌花原基的理论和实际能力有正相关的关系,雌花芽的比值为“+/-”或3.0,营养芽为“-/+”或1.2。对内源激素模式的实际意义,以及核桃童性的本质问题等也进行了讨论。     

黄金梨小孢子败育的解剖学观察

利用石蜡切片法观察了黄金梨花药发育和花粉发育过程中细胞形态变化特点。结果表明，开花时黄金梨花药干瘪，花粉粒极少，每个花药中只有30粒左右花粉，表现出雄性不育的空囊花药；导致花粉败育的主要原因可能是绒毡层细胞在花粉母细胞时期出现畸形，提早解体，致使绝大多数小孢子母细胞不能正常发育；从3月20日开始，绒毡层细胞逐渐解体，花药开始出现空腔，随着时间推移，空腔逐渐加大，到4月1日基本变成空囊花药。花粉粒中没有细胞核，花粉粒细胞壁开始破裂。     

Effect of GA(4 + 7) on the initiation and development of the inflorescence bud of evergreen azalea

Apical buds of evergreen azalea (Rhododendron sp.) were treated with GA(4 + 7) at different stages of development. Treatment of vegetative buds stimulated shoot growth, slightly delayed both flower initiation and development, but increased the number of flower primordia. Treatment at the time of floral transition induced bud abortion at an early stage of the reproductive development. Treatment of inflorescence buds which contained at least one complete flower substituted for chilling in overcoming dormancy and prevented inflorescence bud abortion.