乔木树种体细胞胚胎发生的研究与应用

综述了乔木树种体细胞胚胎发生的研究现状,其中包括体细胞胚胎发生的基本步骤;影响乔木树种体细胞胚胎发生及其植株再生的因素。展望了乔木树种体细胞胚胎发生的应用前景及研究方向,提出了乔木树种体细胞胚胎发生在研究和应用过程中存在的问题。     

针叶树体细胞胚胎发生研究进展

针叶树的体细胞胚胎发生是体细胞在人工无菌培养条件下分化产生体细胞胚胎的过程,体细胞胚胎发生途径是细胞全能性表达的一种方式,重演了合子胚形态发生的过程。自1985年Hakman等首次报道挪威云杉的未成熟合子胚形成体细胞胚并再生植株以来,针叶树体细胞胚的诱导、成熟和植株再生过程的研究取得了巨大进展。综述了针叶树体细胞胚胎发生研究领域的研究进展,总结了影响体细胞胚胎发生的主要因素,展望了这方面的研究在实际生产中的应用前景及发展趋势,并指出了该研究领域中需要解决的主要问题及解决途径。     

青海云杉的引种栽培

青海云杉(Picea crassifolia kom)属松科，云杉属植物，是优良的用材树种，也是一种优良的观赏树种。我地引种的青海云杉表现出以下几个方面的特性。(1)适应性强，从青海引入我地，只是在苗期进行了防寒，能安全越冬。(2)生长速度快，青海云杉与我地的松属、云杉属植物比，其地径、胸径及高生长均明显大于本地树种。抗逆性强，病虫害少，容易栽培，便于管理。     

林木体细胞胚胎发生的研究进展

本文概述了近年国内外林木体细胞胚胎发生研究的进展,针对存在的问题提出相应的对策,以期推动我国林木体细胞胚胎发生研究在理论上的深入和生产上的进一步应用。今后在林木体细胞胚胎发生研究方面应加强以下五方面工作:1)珍稀优异种质规模化体细胞胚胎发生植株再生体系的研究和应用;2)林木成年优树的复壮及体细胞胚胎发生植株再生系统建立;3)进一步加强体细胞胚胎发生机理和应用技术研究;4)进一步扩大林木体细胞胚胎发生再生植株体系建立的树种数量;5)加强体细胞胚胎发生植株再生系统在林木转基因方面的应用技术相关研究。     

沙地云杉生态型表观性状分化

沙地云杉为内蒙古特有树种,干旱适应性强,已成为我国西部重要造林树种。在长期适应干旱生态条件的过程中沙地云杉形成了紫果型、绿果型和红果型等多种生态型。文章对各种生态型沙地云杉的表观性状分化进行了比较研究,可为沙地云杉生态型分化机理研究提供理论参考,对扩大沙地云杉造林面积和西部大开发的生态环境建设具有重要的指导意义。     

优良绿化树种青扦云杉引种栽培技术

青扦云杉 (PiceawilsoniiMast.) ,别名青扦 ,为松科云杉属常绿高大乔木 ,树冠枝叶繁密、层次清晰 ,是一种极为优良的绿化树种。青扦云杉为我国特有树种 ,属稍阴性 ,耐全光 ,适应性强 ;在土壤湿润、深厚、排水良好的微酸性地带生长良好。主要产于内蒙古、河北、山西、青海等省区 ,为我国云杉属中分布较为广泛的树种之一。黑龙江省引种栽培青扦云杉至少有 2 0年的历史 ,只要选择适宜的生长环境 ,青扦云杉就可在黑龙江省南部地区正常生长 ,表现出较强的适应性 ,在园林绿化上具有较高的推广价值。1　种子采集与调制9月下旬当球果由绿色变成黄褐…     

五台山林区云杉病虫害防治技术探讨

云杉为中国特有树种,适应性强、生长快,是五台山林区主要造林树种。介绍了云杉的生活习性和常见的几种病虫害,并提出了防治措施,以期为今后的云杉病虫害防治工作提供参考。     

体细胞胚胎发生杂种马褂木引种试验

对体细胞胚胎发生杂种马褂木引种试验林进行了调查分析,结果表明试验林总体生长良好,生长迅速,在排除造林初期根系恢复及生态适应过程的影响的情况下,年均抽高可达0.95m。体细胞胚胎发生杂种马褂木适应性强,但对水分反应敏感,生长期内降水不足将明显影响其生长。体细胞胚胎发生杂种马褂木在福建省可顺利越冬,生长不会受到冻害影响,但应着重选择降水充足、排水良好的林地造林。     

4种针叶树种引种试验

樟子松、云杉、侧柏、刺柏４种针叶树种在民勤沙生植物园１０多年的引种试验结果表明：樟子松、云杉、刺柏在该地区生长良好，无病虫害发生。云杉、刺柏树形优美，可作庭园、城市绿化树种。樟子松栽植保存率高，生长速度快，适应性强，可作为防护林营造树种。侧柏生长不良，并有锈病发生。     

不同方法提取三种生态型沙地云杉总DNA的比较

沙地云杉为内蒙古特有树种,干旱适应性强,是我国西部重要造林树种。在长期适应干旱生态条件的过程中沙地云杉形成了紫果型、绿果型和红果型3种生态型。前期研究证明:紫果型沙地云杉有更强的抗旱能力,绿果型抗旱能力弱,红果型处于二者之间,是一个比较典型的过渡类型。本文从分子生物学的角度,详细叙述了沙地云杉总DNA的提取过程、方法,并对已知的植物DNA提取方法作了针对性的改良;对实验过程提取DNA的影响作了分析。为今后针对进行沙地云杉的植物基因研究和生物工程打下基础,对扩大沙地云杉造林面积和西部大开发的生态环境建设具有重要的指导意义。     

Tree mortality and habitat shifts in the regeneration trajectory underneath canopy of an old-growth subalpine forest

To better understand tree regeneration trajectories and the resultant coexistence of Abies with co-dominants, Picea jezoensis var. hondoensis, Tsuga diversifolia and Betula ermanii, in an old-growth subalpine forest, we investigated spatial mortality patterns during the regeneration of Abies mariesii and A. veitchii, which are abundant in the understory reflecting their shade tolerance. Regeneration of these Abies spp. from shaded understory to canopy status is affected by other canopy co-dominants. Snags of understory Abies spp. were common, suggesting that the primary mortality agent is suppression by the overstory. Although live, small Abies trees in the understory were positively associated with a Picea canopy, the long-term survival was reduced among Abies trees close to the canopy, suggesting that shading by large Picea in the overstory negatively affects understory Abies plants. The existence of shade-intolerant canopy co-dominants such as Picea and also Tsuga, which are larger and longer lived than the shade-tolerant Abies, may play an important role in preventing the Abies spp. from competitively displacing these other tree species, which are much rarer in the understory, though common in the canopy. Moreover, in spite of the fact that Betula canopies fostered recruitment and growth of Abies saplings, Abies showed no association with Betula canopy and their survival at later-stage was rather reduced near or beneath Betula canopies at the subsequent understory small tree stage. Based on spatially significant events related to tree death, this study detected such “habitat shifts” in the trajectory of tree regeneration. Accordingly, it can be concluded that careful consideration of the regeneration habitat is required for a fuller understanding of ecological processes in spatially complex old-growth forest systems.     

Predicting tree regeneration in <Emphasis Type="Italic">Picea abies</Emphasis> snag stands

A bark beetle (Ips typographus) infestation caused the death of almost all Norway spruce (Picea abies) trees in a mountain forest in the Swiss Alps. We developed a tree regeneration model, ‘RegSnag’ (=REGeneration in a SNAG stand), to project the future amount and height of tree regeneration in these snag stands. The model combines a height-class structured tree module with a microsite-based module of snag decay and ground-vegetation succession. Microsite-specific rates of germination, mortality and height growth were modelled for four tree species (Picea abies, Sorbus aucuparia, Acer pseudoplatanus and Betula pendula) in eight height classes (from seedlings to saplings 5 m tall) and on 26 microsite types (e.g. moss, grass). Model tests with independent field data from 8 years after the Picea die-back demonstrated that microsites had a considerable effect on the development of tree regeneration on both the montane and the subalpine level. With microsite-specific parameters, the height and frequency of Picea in each microsite could be simulated more accurately than without considering microsite effects (e.g. bias of 8 vs. 119 saplings ha⁻¹ on the montane level). Results of simulations 40 years into the future suggest that about 330–930 Picea saplings per ha out of those that germinated in 1994 and 1996 will reach a height of 5 m within 30–35 years after Picea die-back. This is due to differences in seed inflow and browsing intensities. Picea and not Betula or Sorbus trees will replace the current herbaceous vegetation in these snag stands.     

云杉属树种谱系地理学研究

云杉属谱系地理学主要是研究云杉属种群遗传结构的历史动态规律，以及气候振荡和地质变迁对种群分布范围、种群间基因渐渗及遗传分化的影响。文中综述了国内外云杉属谱系地理学的研究进展，结论如下:我国西南山区和青藏高原（QTP）地区云杉属树种谱系地理学研究，验证了上新世QTP上升和第四纪冰期气候振荡对该物种进化起到推动作用，该物种在这2个时期快速分化；在云杉属争议种的研究中，通过对云杉属复合种群的群体结构展开研究，揭示了种群间的基因渐渗常存在于有较低基因流的基因组，方向通常是由本土树种向入侵树种渗透；某些种群之间的基因渐渗可有助于在一些基因位点上增加这些种群和其他种群之间的分化，导致生殖隔离的产生；云杉属天然杂种多被发现在种群的对称分布区边缘、或者其重叠分布区，杂种经过异地扩张又形成了新种，验证了云杉属网状进化的历史，并证明了生境特征决定杂交优势种的分布边界。     

miR396在落叶松体细胞胚胎中的功能研究

[目的]探讨miR396在落叶松体细胞胚胎发生中的功能.以期该研究能为解决体胚发育中子叶畸形胚与生根率低的问题提供新的视角,同时也为进一步揭示体胚发育的分子调控网络做基础铺垫.[方法]构建pre-miR396超表达载体,通过农杆菌介导侵染,将pre-miR396转入落叶松胚性细胞中,筛选稳定抗性细胞系.在DNA与RNA水平上,对抗性细胞系进行的鉴定、检测,同时统计比对其与野生细胞系间发芽率、叶片数目以及生根率的差异.[结果]在抗性细胞系基因组中,扩增出HTP与miR396的特异性片段,且无农杆菌Virg基因片段.RNA表达水平上,抗性系pre-miR396与miR396表达皆增加,而靶基因LaGRFs的表达量下调.统计表明抗性系胚的发芽率、生根率、叶片数目畸形率分别为70.60%、0.60%、37%,而野生型分别为92.50%、10.55%、4%,抗性系胚的发芽率、生根率显著降低(Sig.=0.000),叶片数目畸形率显著增加(Sig.=0.000).[结论]miR396在落叶松体细胞胚胎发生过程中,可能通过负调节靶基因LaGRFs的表达或者通过LaGRFs影响与它相互作用的基因,参与体胚子叶原基细胞代谢,从而影响了子叶与叶片的发育;通过负调节LaGRFs或者其它与根部发育相关的靶基因,影响了根端分生区细胞的活动,参与调控根的发育.     

Application of biotechnological tools to Quercus improvement

The genus Quercus, which belongs to the family Fagaceae, is native to the northern hemisphere and includes deciduous and evergreen species. The trees of the different species are very important from both economic and ecological perspectives. Application of new technological approaches (which span the fields of plant developmental biology, genetic transformation, conservation of elite germplasm and discovery of genes associated with complex multigenic traits) to these long-rotation hardwoods may be of interest for accelerating tree improvement programs. This review provides a summary of the advances made in the application of biotechnological tools to specific oak species. Significant progress has been made in the area of clonal propagation via organogenesis and somatic embryogenesis (SE). Standardized procedures have been developed for micropropagating the most important European (Q. robur, Q. petarea, Q. suber) and American (Q. alba, Q. bicolor, Q. rubra) oaks by axillary shoot growth. Although regenerated plantlets are grown in experimental trials, large-scale propagation of oak species has not been carried out. The induction of SE in oaks from juvenile explants is generally not problematic, although the use of explants other than zygotic embryos is much less efficient. During the last decade, enormous advances have been made in inducing SE from selected adult trees, mainly specimens of pedunculate oak (Q. robur) and cork oak (Q. suber). Advances in the understanding of the maturation and germination steps are required for better use of embryogenic process in clonal forestry. Quercus species are late-maturing and late-flowering, exhibit irregular seed set, and produce seeds that are recalcitrant to storage by conventional procedures. Vitrification-based cryopreservation techniques were used successfully in somatic embryos of pedunculate oak and cork oak, and an applied genbank of cork oak selected genotypes is now under development. The feasibility of genetic transformation of pedunculate oak and cork oak somatic embryos by means of co-culture techniques with several strains of Agrobacterium tumefaciens has also been demonstrated. To date, most research on the genomics of Quercus species has concerned population genetics. Approaches using functional genomics to examine the molecular and cellular mechanisms that control organogenesis and or somatic embryogenesis are still scarce, and efforts on the isolation and characterization of genes related to other specific traits should be intensified in the near future, as this would help improve the practical application of clonal forestry in recalcitrant species such as oaks.     

Radial growth patterns of dominant trees in two old-growth forests in eastern Fennoscandia

We investigated the characteristics and variability of radial growth patterns and the occurrence of growth releases in dominant trees in two old-growth forests in eastern Finland, one dominated by Picea abies and the other by Pinus sylvestris. The dominant trees exhibited high variation in radial growth patterns suggesting that the trees had experienced very different growing conditions and competitive situations during their lifespans. Based on visual evaluation, five types of radial growth patterns were distinguished: descending, even, unimodal (one peak in the growth rate), bimodal (two peaks in the growth rate with an intermediate depression) and fuzzy (no clear pattern). One or more growth releases were detected in 18% of the sampled Picea and in 21% of the Pinus trees. In both the Picea- and the Pinus-dominated sites, the temporal distribution of growth releases was relatively even, except for a moderate peak in 1855–1860. This suggests that small-scale disturbances have been the predominant disturbance mode in both sites during the last 150 years. We conclude that the detected variability in radial growth patterns likely reflects the overall small-scale heterogeneity of structure and developmental processes that are typical of old-growth forests.     

Somatic embryogenesis inCephalotaxus harringtonia embryo-megagametophyte co-culture

Somatic embryogenesis was initiated fromCephalotaxus harringtonia (Forbes) K. Koch embryo culture. Explants consisted of embryo and megagametophyte halves both cut longitudinally. They were removed aseptically from mature seeds and grown together on a solid Murashige and Skoog modified medium supplemented with 5 mg·l ⁻¹ 2,4-dichlorophenoxyacetic acid. Embryogenic cultures started from callus after three or more months on the primary medium. The embryogenic callus originated from the suspensor region of the embryo. All chromosome counts made in the cells of the embryonic structures demonstrated a diploid stage, which suggest that they originated from zygotic embryo tissue. The early stages of somatic embryogenic development were achieved,i.e., formation of small clusters consisting of an embryonal region made up of isodiametric meristematic cells. A more advanced stage was reached in some cultures in which the distal embryonal end of the embryo appeared smooth and opaque. The ultrastructural characteristics of the embryos, the two types of embryo cells, embryonal and suspensor cells, as well as their contents were similar to those already reported in the case of somatic embryogenesis of other conifers.     

Monitoring genetic stability inQuercus serrata Thunb. somatic embryogenesis using RAPD markers

Genetic stability of propagules regeneratedvia somatic embryogenesis is of paramount importance for its application to clonal forestry. Random amplified polymorphic DNA (RAPD) markers were used to determine the genetic stability in somatic embryogenesis ofQuercus serrata Thunb. (Japanese white oak). Forty samples from an embryogenic line, consisting of regenerated plantlets, somatic embryos, and embryogenic calli, were examined using 54 decanucleotide primers. A total of 6520 clear reproducible bands obtained from these studies exhibited no aberration in RAPD banding pattern among the tested samples. Our results show that somaclonal variation is absent in our plant propagation system. The genetic stability is discussed in terms of the origin of somatic embryos.     

From broadleaves to spruce – the borealization of southern Sweden

Mixed or broadleaf forests were once common in many regions of Northern Europe, whereas today conifers often dominate. The aim of the study was to investigate the spatial and temporal patterns and processes which underlie this transition to Picea abies dominance in southern Sweden. We use recently developed paleoecological methods to determine long-term changes in the relative abundance of tree species, and digitalized National Forest Inventory (NFI) databases to assess more recent changes in the spatial coverage of Picea throughout the region. The novel combination of the two databases reveals that Picea became a widespread and abundant species in many parts of southern Sweden around 1000 years ago. After a brief decline in abundance starting around 500 years ago, NFI data indicate a rapid increase in the volume of Picea between 1920 and 1950, prior to the large-scale introduction of Picea-dominated plantation forests. The available evidence suggests that abandonment of forest grazing and slash-and-burn cultivation, as well as selection cutting benefited the natural establishment and growth of Picea during the first half of the twentieth century. Hence, prior to the impacts of industrialized forestry that began in the 1950s, other processes were already favouring increased Picea abundance.