AFLP analysis of somaclonal variations in Eucalyptus globulus

DNA variations of forty-eight Eucalyptus globulus plants, regenerated by successive culture from seven different explants were assessed by AFLP analysis using 18 primer combinations. At least one variation showed 66.7 % of the analyzed plants, and the numbers of polymorphic bands per plant ranged from 1 to 22. The proportion of polymorphic fragments did not correlate with the numbers of the regenerated plants. However, the more times of successive culture were done the more of polymorphic bands were found within the groups. On average, between 97.39 and 99.88 % of all fragments were shared within the same group. AMOVA analysis showed 39.33 % of the variation was found among the accessions that originated from different calli while 60.67 % was from same calli.     

An unusual Xanthophyllomyces strain from leaves of Eucalyptus globulus in Chile

Xanthophyllomyces sp. was isolated as an epiphytic red yeast from leaves of Eucalyptus glo-bulus in Concepción, Chile. Sexual reproduction was by basidiospores produced from one or rarely two metabasidia arising from a yeast cell without preceding paedogamy. The main carotenoid pigment was astaxanthin. This isolate did not cluster with the X. dendrorhous complex (including Phaffia rhodozyma) in ITS and 26S rDNA-based phylogenetic analyses. The phylloplane may be a further habitat for Xanthophyllomyces, in addition to the well-known spring sap-flows of deciduous trees and the recently-characterised ascostromata of Cyttaria hariotii.     

Discovery, validation, and in silico functional characterization of EST-SSR markers in Eucalyptus globulus

Eucalyptus globulus is the most commonly planted hardwood species for pulpwood in temperate regions. We aimed to develop and characterize functional molecular markers for population genetic analyses and molecular breeding in this model tree species. Public expressed sequence tag (EST) databases were screened for nonredundant sequences to predict putative gene functions and to discover simple sequence repeats (EST-SSRs), which were then validated in E. globulus and six other Eucalyptus species. A total of 4,924 nonredundant sequences were identified from 12,690 updated E. globulus ESTs. Approximately 19.3% (952) were unigenes and contained 1,140 EST-SSR markers, which were mainly trimeric (58.6%). A set of 979 primers for putative SSR markers was designed after bioinformatic analysis. The predicted functions of these ESTs containing SSR were classified according to their gene ontology (GO) categories (biological process, molecular function, and cellular component). GO categories were assigned to 226 ESTs (30.2%). Most ESTs containing SSR (78.7%) had significant matches (E ≤ 10⁻⁵) with the nonredundant protein database using BLASTX. From a set of 56 random primer pairs, 37 could be validated in eight E. globulus genotypes and were also tested for cross-transferability to other six Eucalyptus species (Eucalyptus grandis, Eucalyptus saligna, Eucalyptus dunnii, Eucalyptus viminalis, Eucalyptus camaldulensis, Eucalyptus tereticornis). Seventeen polymorphic EST-SSR markers for E. globulus were evaluated in 60 unrelated trees, being representative of the species’ natural distribution. As a result, six highly informative markers were proposed for genetic diversity analyses, fingerprinting, and comparative population studies, between different species of E. globulus.     

Tree-ring structure and climatic effects in young Eucalyptus globulus Labill. grown at two Portuguese sites: preliminary results

Dendrochronological analyses of Eucalyptus are generally rare and mostly restricted to Australia. This work reports an attempt to identify annual ring patterns in young blue gum trees (Eucalyptus globulus Labil) grown in Europe through studying the radial variation of vessel characteristics. Common radial trends were seen such as increasing vessel areas, decreasing vessel abundances and a cyclic variability of vessel characteristics associated to the seasons. Low water availability was related to reduced ring widths in combination with more and smaller vessels. Even with the given juvenility of the investigated eucalypt trees the pith to bark trends of vessel parameters might be useful in dendroecological studies, particularly with respect to drought scenarios. The employed method of using vessel parameters to identify rings seem to be the only accurate way of identifying annual rings in E. globulus.     

蓝桉凋落叶分解对菠菜生长及光合特性的影响

通过盆栽试验,模拟蓝桉(Eucalyptus globulus)凋落叶在土壤中分解对受体植物菠菜(Spinacia oleracea)生长及光合特性的影响,设置L30(30 g/盆)、L60(60 g/盆)、L90(90 g/盆)和L120(120 g/盆)4个凋落叶施用水平,对照(CK)不加凋落叶。结果表明:(1)在分解30 d时,低量的凋落叶(L30)未抑制菠菜生物量的积累,而中量和高量处理(L60、L90和L120)下其生物量显著降低(P0.05);在凋落叶分解50 d后,蓝桉凋落叶的化感抑制效应已经减弱,仅L120仍然抑制菠菜生物量的积累;(2)一定量的凋落叶(L30和L60)对菠菜叶绿素的合成有促进作用,而凋落叶超过一定量时(L120)转为抑制作用,在凋落叶分解28 d时相对不明显,40 d后逐渐显现;(3)经凋落叶处理的菠菜叶片胞间CO2浓度(Ci)、气孔导度(Gs)及蒸腾速率(Tr)均显著高于对照(CK)(P0.05),而净光合速率(Pn)在L30处理下最高,L60和L90处理与CK差异不显著,仅L120处理显著低于CK(P0.05);(4)光响应与CO2响应曲线的特征参数表观量子效率(AQY)、最大净光合速率(Pmax)、光饱和点(Lsp)、光补偿点(Lcp)、暗呼吸速率(Rd)、Ru BP表观羧化效率(CE)和光呼吸速率(Rp)在L30处理下高于CK,其余凋落叶处理均低于CK,而CO2饱和点(Csp)、CO2补偿点(Ccp)随凋落叶量的增加而升高。综合各指标可见,少量的蓝桉凋落叶分解(L30)可通过增加叶绿素含量,提高对光和CO2的利用能力促进菠菜的光合作用,进而促进其生长,而凋落叶超过一定量时(L90—L120)则起到相反的作用。     

Efficient plant regeneration from seedling explants of two commercially important temperate eucalypt species–Eucalyptus nitens and E. globulus

A reliable and reproducible method for plant regeneration in vitro of two important temperate eucalypts, Eucalyptus nitens and E. globulus, has been developed which utilises seedling explants. Highly regenerative callus was obtained from individual cotyledon and hypocotyledon explants of both species following cultivation on Murashige and Skoog’s (MS) basal nutrient medium supplemented with 30 g l⁻¹ sucrose, 5–10% (v/v) coconut water, 0.8% agar, 1 mg l⁻¹ -naphthalene-acetic acid (NAA) and 0.5 mg l⁻¹ N⁶ benzylaminopurine (BAP). Shoot differentiation was observed 7–8 weeks after transfer of callus onto regeneration medium containing 0.5 mg l⁻¹ NAA and 1 mg l⁻¹ BAP. In a few instances, direct shoot regeneration occurred without an intervening callus phase in both species. The frequency of plant regeneration was higher for callus derived from hypocotyl segments (30–35%) compared to cotyledonary explants (20–25%) though the average number of shoots per cotyledonary explant was generally higher than for hypocotyl explants. Somatic embryos were observed occasionally in E. nitens, arising from the surface of organogenic callus. Organised structures closely resembling somatic embryos were also observed in E. globulus. Regenerated shoots (30–40%) of both species could be rooted in modified MS media containing indole-3-butyric acid (IBA) and plantlets were successfully transferred to soil.     

Contribution of the saprobic fungi Trametes versicolor and Trichoderma harzianum and the arbuscular mycorrhizal fungi Glomus deserticola and G. claroideum to arsenic tolerance of Eucalyptus globulus

The presence of high concentrations of arsenic (As) decreased the shoot and root dry weight, chlorophyll and P and Mg content of Eucalyptus globulus colonized with the arbuscular mycorrhizal (AM) fungi Glomus deserticola or G. claroideum, but these parameters were higher than in non-AM plants. As increased the percentage of AM length colonization and succinate dehydrogenase (SDH) activity in the root of E. globulus. Trichoderma harzianum, but not Trametes versicolor, increased the shoot and root dry weight, chlorophyll content, the percentage of AM root length colonization and SDH activity of E. globulus in presence of all As concentrations applied to soil when was inoculated together with G. claroideum. AM fungi increased shoot As and P concentration of E. globulus to higher level than the non-AM inoculated controls. The contribution of the AM and saprobe fungi to the translocation of As from root to shoot of E. globulus is discussed.     

大叶桉挥发物对蚕豆细胞毒性效应及信号调节

为探讨大叶桉(Eucalyptus robusta)化感作用的细胞学机制，该研究以大叶桉挥发油及其主要成分α-蒎烯和桉油精为供体，以蚕豆(Vicia faba)的根细胞和叶保卫细胞为靶标，运用显微技术、细胞化学技术和qRT-PCR技术，研究了大叶桉挥发物的毒性效应。结果表明：(1)在大叶桉挥发物作用下，蚕豆幼根生长受抑制并表现为时间-浓度依赖效应，其化感效应强弱由大到小依次为挥发油、α-蒎烯和桉油精。(2)蚕豆根边缘细胞活性降低，分生区细胞微核率升高，有丝分裂指数下降且大部分细胞的细胞周期被阻滞在分裂前期。(3)蚕豆叶保卫细胞内NADPH氧化酶活性升高，活性氧(reactive oxygen species, ROS)爆发，微丝聚合，气孔开度下降；叶保卫细胞的核畸变率升高，细胞活性降低甚至发生caspase依赖性细胞凋亡，而Ca²⁺通道阻断剂(LaCl₃)、活性氧清除剂(AsA)和硝酸还原酶抑制剂(NaN₃)均可显著提高保卫细胞存活率，说明大叶桉挥发物改变了信号分子Ca²⁺、ROS和NO的信号调节。...     

不同林龄巨尾桉的灰分含量和热值

采用热量仪和马福炉对1～4年生4个不同林龄阶段巨尾桉的叶、枝、根、干、皮5个部位进行灰分含量和热值测定,结果表明:不同林龄巨尾桉其5个部位的平均灰分含量在(0.42±0.14)%～(4.43±1.35)%之间,以皮的最高、干的最低,各部位灰分含量的大小排列顺序无一相同且无明显的规律可循,除根外,叶、枝、干、皮在林分4个...     

巨尾桉叶片挥发物对三种植物种子萌发及幼苗生长的化感效应

为探讨人工巨尾桉林叶片挥发物对周边农作物的化感作用,采用不同质量新鲜巨尾桉叶片及由新鲜叶片提取的桉叶油对玉米、辣椒、西红柿等三种植物种子进行处理,观测其种子萌发和幼苗生长状况。结果表明:(1)在三种被测植物中,桉树叶片挥发物对玉米种子萌发影响最小,对辣椒影响最大;(2)当叶片用量小于200g时,桉树叶片挥发物对三种植物种子萌发影响不明显,当叶片用量达400g时,能完全抑制辣椒、西红柿种子萌发,并能极显著降低玉米种子萌发(P0.01);(3)玉米幼苗芽生长随叶片用量的增加呈现先促进后抑制现象,对芽高、鲜重、干重的促进和抑制均达到显著(P0.05)或极显著水平(P0.01);(4)当叶片用量小于或等于100g时,桉树叶片挥发物对辣椒、西红柿幼苗生长影响不明显,当用量达到200g时则能极显著抑制辣椒、西红柿幼苗生长;(5)桉叶油对三种测试植物的抑制效果与叶片自然挥发物相似,且效果更显著。     

巨桉种源/家系综合选择研究

为选择巨桉(Eucalyptus grandis)优良种源,对其13个种源177个家系性状进行遗传分析。结果表明,22月生巨桉除生长量在区组间差异显著外,其他性状在种源、家系和区组间均存在极显著的差异;50月生时各性状差异均达极显著水平。50月生时,单株材积位于前四的种源分别是2号(来自昆士兰州Copperlode)、3号(来自昆士兰州Ravenshoe)、1号(来自昆士兰州N W Townsille)和11号(来自四川省黑龙滩)。50月生时,有78个家系的单株材积增长量超过总体家系平均值(0.08 m3),位于前三的家系是分别为2号(来自2号种源)、156号(来自福建天马东溪的10号种源)和93号(来自昆士兰州Bambaroo的8号种源)。50月生巨桉的胸径、树高、单株材积、干形、分枝和冠幅的遗传力分别为0.56、0.91、0.73、0.67、0.64和0.76;这些性状的表型变异系数分别为26.64%、29.37%、64.41%、17.58%、15.26%和45.80%;遗传变异系数分别为25.94%、24.30%、60.97%、28.59%、26.07%和42.96%。相关性分析表明,冠幅和分枝呈较小的负相关,其余各性状间均呈正相关性。结合生长指标和形质指标,最终筛选出4个优良种源和18个优良家系。     

巨桉SuSy基因家族的生物信息学分析

为了解EgrSuSy基因家族的生物学功能,从巨桉(Eucalyptusgrandis)基因组数据库中筛选出18个SuSy基因家族成员(EgrSuSy1～EgrSuSy18),采用生物信息学方法对其基因特征与表达模式进行分析。结果表明,EgrSuSy基因分布在7条染色体上,EgrSuSy蛋白均定位在细胞质膜上,EgrSuSy家族成员均不具备信号肽。EgrSuSy蛋白质由α-螺旋、延伸链、无规则卷曲、β-转角组成。EgrSuSy蛋白与毛果杨(Populustrichocarpa)的SuSy蛋白亲缘关系相近。18个EgrSuSy基因在巨桉未成熟木质部、成熟叶片、韧皮部、茎尖、木质部以及幼叶组织中的表达模式不同。因此,EgrSuSy在巨桉不同组织和发育时期的功能可能存在差异。     

Phytotoxic effects of Lantana camara, Eucalyptus camaldulensis and Eriocephalus africanus essential oils in weeds of Mediterranean summer crops

The essential oil composition of Lantana camara, Eucalyptus camaldulensis and Eriocephalus africanus was analyzed by means of GC and GC–MS and bioassayed in order to determine their activity against Amaranthus hybridus and Portulaca oleracea. E. camaldulensis essential oil, with spathulenol as the main compound, was the most effective, completely inhibiting germination and seedling growth on both weeds. The essential oil of E. africanus, rich in artemisia ketone, showed activity similar to that of E. camaldulensis on A. hybridus, but it was not so effective against P. oleracea, and L. camara essential oil, with high percentages in sesquiterpene hydrocarbons, also showed higher phytotoxic activity against A. hybridus, inhibiting its germination and seedling length; however, it showed no effect against P. oleracea germination, whereas was effective in significantly reducing its seedling growth at all concentrations assayed. The results suggest the possible use of these essential oils as natural herbicides.     

Joint modeling of additive and non-additive genetic line effects in single field trials

A statistical approach is presented for selection of best performing lines for commercial release and best parents for future breeding programs from standard agronomic trials. The method involves the partitioning of the genetic effect of a line into additive and non-additive effects using pedigree based inter-line relationships, in a similar manner to that used in animal breeding. A difference is the ability to estimate non-additive effects. Line performance can be assessed by an overall genetic line effect with greater accuracy than when ignoring pedigree information and the additive effects are predicted breeding values. A generalized definition of heritability is developed to account for the complex models presented.     

巨桉AGO基因家族的生物信息学分析

为了解巨桉(Eucalyptus grandis)中Argonaute (AGO)的功能, 经全基因组序列分析, 巨桉中存在14 个AGO基因家族成员, 基因长度为2676~3225 bp, 编码的蛋白质具有保守的Piwi、PAZ、DUF1785 结构域。巨桉EgrAGOs 基因可分为3 组, 内含子和外显子结构具有明显的组织特异性。组内成员核苷酸序列和氨基酸序列保守性较高, 同源性分别达到88.14% 和82.97%。EgrAGO基因分布于第2、4、7、8、10、11 条染色体上, 在进化过程中存在着串联复制和大片段基因复制机制。预测巨桉的大部分AGO 蛋白定位于细胞核和胞质中, 表现出偏碱性和亲水性, 具有较高的脂溶指数。基因表达分析表明, 桉树EgrAGO成员在不同组织中的表达有明显差异, 与木材形成相关的组织/ 器官中有较高的表达。这些为深入研究EgrAGO基因的功能奠定了基础。     

The effect of non-additive genetic interactions on selection in multi-locus genetic models

Additive genetic variance might usually be expected to decrease in a finite population because of genetic drift. However, both theoretical and empirical studies have shown that the additive genetic variance of a population could, in some cases, actually increase owing to the action of genetic drift in presence of non-additive effects. We used Monte-Carlo simulations to address a less-well-studied issue: the effects of directional truncation selection on a trait affected by non-additive genetic variation. We investigated the effects on genetic variance and the response to selection. We compared two different genetic models, representing various numbers of loci. We found that the additive genetic variance could also increase in the case of truncation selection, when dominance and epistasis was present. Additive-by-additive epistatic effects generally gave a higher increase in additive variance compared to dominance. However, the magnitude of the increase differed depending on the particular model and on the number of loci.     

Complex effects of the gastropod Assiminea globulus on benthic community structure in a marine-dominated lagoon

Grazing is a key factor structuring aquatic communities, and can have both positive and negative effects. Here, we report on the effects of an intertidal estuarine gastropod, Assiminea globulus, on sediment bacteria, microphytobenthos and meiofauna, based on field observations and manipulative experiments. Field observations showed inconsistent patterns of chlorophyll-a concentrations in zones occupied by A. globulus relative to zones lacking this species, and meiofaunal density increased downshore. Bacterial density, however, was always consistently and significantly elevated in zones of A. globulus across all sites sampled, suggesting promotion of bacterial density by this snail. Field experiments were more conclusive, showing a significant negative effect of A. globulus on sediment chlorophyll-a levels at both the surface and at a sediment depth of 2 cm, but positive effects on bacterial density at both depths. A. globulus density did not affect overall meiofaunal density, but did affect meiofaunal community structure, generally by depressing the density of harpacticoid copepods but promoting platyhelminthes, and enhancing taxonomic diversity at high density. The complex effects of A. globulus probably reflect the interactive effects of bioturbation, fertilisation, grazing and pelletisation, all of which need to be considered when understanding grazer effects on soft-sediment communities.     

巨桉BRI1基因的克隆和表达分析

为了解BRI1基因在巨桉中的功能,采用PCR技术克隆了EgrBRI1基因,分析了EgrBRI1的生物信息学和亚细胞定位,并对EgrBRI1基因响应激素和胁迫的差异表达进行了分析。结果表明,EgrBRI1基因全长3 893 bp,编码1 197个氨基酸。EgrBRI1蛋白稳定,空间结构复杂,存在3个motifs,主要定位于细胞膜。茉莉酸甲酯和油菜素内酯(BR)处理后,EgrBRI1基因在叶片中的表达上升,而水杨酸处理则没有明显的变化。盐胁迫和冷胁迫下,EgrBRI1基因表达表现为先下降后上升的趋势。因此,EgrBRI1基因能快速对外施激素做出响应,并在巨桉抗逆方面发挥重要作用,这可能是通过对BR信号的响应来实现的。