Genetic control of Eucalyptus urophylla and E. grandis resistance to canker caused by Chrysoporthe cubensis

Chrysophorte cubensis induced canker occurs in nearly all tropical and subtropical regions where eucalypts are planted, causing losses in both wood quality and volume productivity, especially so in the warmer and more humid regions of Brazil. The wide inter and intra-specific genetic variability of resistance to canker among Eucalyptus species facilitates the selection of resistant plants. In this study, we evaluated resistance to this pathogen in five Eucalyptus grandis (G) and 15 E. urophylla (U) trees, as well as in 495 individuals from 27 progenies derived from crosses between the trees. In the field, six-months-old test seedlings were inoculated with C. cubensis. Lesion length in the xylem and bark was measured eight months later. The results demonstrated that xylem lesions could preferentially be used for the selection of resistant clones. Eight trees (7 U and 1 G) were susceptible, and the remainder (8 U and 4 G) resistant. Individual narrow and broad sense heritability estimates were 17 and 81%, respectively, thereby suggesting that canker resistance is quantitative and highly dependent on dominance and epistasis.     

Genomic predictions of breeding values in a cloned <Emphasis Type="Italic">Eucalyptus globulus</Emphasis> population in Chile

In Chile, an intensive Eucalyptus globulus clonal selection program is being carried out to increase forest productivity for pulp production. A breeding population was used to investigate the predicted ability of single nucleotide polymorphism (SNP) markers for genomic selection (GS). A total of 310 clones from 53 families were used. Stem volume and wood density were measured on all clones. Trees were genotyped at 12 K polymorphic markers using the EUChip60K genotype array. Genomic best linear unbiased prediction, Bayesian lasso regression, Bayes B, and Bayes C models were used to predict genomic estimated breeding values (GEBV). For cross-validation, 260 individuals were sampled for model training and 50 individuals for model validation, using 2 folds and 10 replications each. The average predictive ability estimates for wood density and stem volume across the models were 0.58 and 0.75, respectively. The average rank correlations were 0.59 and 0.71, respectively. Models produced very similar bias for both traits. When clones were ranked based on their GEBV, models had similar phenotypic mean for the top 10% of the clones. The predicted ability of markers will likely decrease if the models are used to predict GEBV of new material coming from the breeding program, because of a different marker–trait phase introduced by recombination. The results should be validated with larger populations and across two generations before routine applications of GS in E. globulus. We suggest that GS is a viable strategy to accelerate clonal selection program of E. globulus in Chile.     

Phenotypic plasticity of growth trajectory and ontogenic allometry in response to density for eucalyptus hybrid clones and families

BACKGROUND: and Aims Response to density is a crucial aspect of the ecology of trees in forests and plantations. Few studies have investigated the genetics of plasticity in response to density for growth traits such as height and circumference through development. METHODS: Two experiments were carried out in the field, the first with full-sib families of Eucalyptus urophylla x E. grandis hybrids, and the second with clones of E. tereticornis x E. grandis hybrids planted across a range of densities (625, 1111 and 2500 trees ha-1). Height, circumference and stem taper were measured through development in both experiments. Variance components were estimated and a repeated measure approach for plasticity and three different methods were used to compare the variance-covariance matrix across densities. KEY RESULTS: Genetic variance was significantly different from zero but the density x genotype interaction was significant only for clone experiments at the adult stage. Significant plasticity for three traits in both experiments was found. In the clone experiments, a significant clone x time x density interaction was found, suggesting that plasticity for growth and stem form is under genetic control. In both experiments, density did not affect environmental correlation, which remained high throughout tree development. The impact of density on genetic correlation was marked in the clone experiment, with a reduced value at lower density, but was not observed in the family trial. The differences between clones and family are mainly explained by the distribution of genetic variation within and among genotypes. CONCLUSIONS: The results suggest that plasticity for growth traits and form of tropical Eucalyptus species is under genetic control and that the environment changes genetic co-variation through ontogeny. The findings confirm that a tree population with a narrow genetic basis (represented by clones) is sensitive to a changing environment, whereas a population with a broader genetic basis (full-sib family here) exhibits a more stable reaction.     

甘露糖正向筛选体系在巨尾桉遗传转化中的应用

为了研究甘露糖正向筛选体系在巨尾桉遗传转化过程中的有效性,构建了以6-磷酸甘露糖异构酶（6-phosphomannose isomerase,PMI）为筛选标记的pCAMBIA1301植物表达载体,并将该载体通过农杆菌介导的遗传转化转入木本植物巨尾桉中。将获得的阳性植株通过氯酚红（chlorophenol red,CPR）法及PCR检测,桉树遗传转化的阳性率达到26.09%。另外,通过正交试验优化法,对巨尾桉组培快繁体系建立过程中不同浓度激素配比进行了研究,建立起良好的巨尾桉组织培养再生体系,由甘露糖筛选敏感性测试,获得了巨尾桉筛选临界浓度,蔗糖与甘露糖比例为19∶11,优化了巨尾桉遗传转化体系,为今后巨尾桉组织培养与遗传转化研究提供了重要的参考依据。     

Removal of nitrogen and phosphorus by Eucalyptus and Populus at a tertiary treated municipal wastewater sprayfield

Various progenies of Eucalyptus grandis and E. amplifolia, and clones of Populus deltoides, were evaluated for plant removal of nitrogen (N) and phosphorus (P) for 26 months at a municipal waste spray field in north Florida. Tertiary treated wastewater containing 2.73 mg L(-1) nitrate N and 0.30 mg L(-1) total P was applied using sprinkler irrigation (93.8 m3 ha(-1) d(-1)) to fast growing trees utilized for bioenergy. Eucalyptus amplifolia and E. grandis survived and grew very poorly as the result of severe winter injury in two successive years and were not evaluated for nutrient removal. Survival and growth of P. deltoides demonstrated suitability for phytoremediation, and selected clones were evaluated for biomass and nutrient content. Removals of total N (TN) and total P (TP) were greatest for main stem (36% and 44%, respectively) and foliage (44% and 36%, respectively). Low biomass producing clones generally had higher nutrient concentrations, but high biomass producing clones removed more TN and TP. Approximately 789 kg ha(-1) TN and 103 kg ha(-1) TP were removed by the highest biomass producing P. deltoides clone, representing 215% of N and 615% of P inputs.     

Eucalyptus infestation by Leptocybe invasa in Uganda

Very little is known about Leptocybe invasa Fisher & LaSalle, a new fast-spreading alien pest infesting Eucalyptus in several countries. This study examined L. invasa infestation on Eucalyptus germplasms in different agroecological zones of Uganda. The incidence and severity of the pest infestation were higher in hotter and drier agroecological zones than in cooler and wetter zones. There were direct negative relationships between altitude and L. invasa infestation on Eucalyptus species. No infestation was observed on any Eucalyptus species in stands at altitudes ranging from 1938 to 2452 (the maximum encountered) m above sea level. Leptocybe invasa infestation occurred on all Eucalyptus species encountered ( Eucalyptus grandis , Eucalyptus camaldulensis , Eucalyptus saligna , Eucalyptus robusta ), except Eucalyptus maidenii that escaped attack because it was located outside the ecological range of the insect. The incidence and severity of L. invasa infestation was generally higher on clonal hybrids E. grandis  ×  E. camaldulensis than on E. grandis  ×  Eucalyptus urophylla . Research on host germplasms, L. invasa biology and ecology, impact of the pest infestation and possible control strategies are suggested to facilitate the development of sustainable management strategies.     

Genetic Mapping of Quantitative Trait Loci Controlling Growth and Wood Quality Traits in Eucalyptus Grandis Using a Maternal Half-Sib Family and Rapd Markers

Quantitative trait loci (QTL) mapping of forest productivity traits was performed using an open pollinated half-sib family of Eucalyptus grandis. For volume growth, a sequential QTL mapping approach was applied using bulk segregant analysis (BSA), selective genotyping (SG) and cosegregation analysis (CSA). Despite the low heritability of this trait and the heterogeneous genetic background employed for mapping. BSA detected one putative QTL and SG two out of the three later found by CSA. The three putative QTL for volume growth were found to control 13.7% of the phenotypic variation, corresponding to an estimated 43.7% of the genetic variation. For wood specific gravity five QTL were identified controlling 24.7% of the phenotypic variation corresponding to 49% of the genetic variation. Overlapping QTL for CBH, WSG and percentage dry weight of bark were observed. A significant case of digenic epistasis was found, involving unlinked QTL for volume. Our results demonstrate the applicability of the within half-sib design for QTL mapping in forest trees and indicate the existence of major genes involved in the expression of economically important traits related to forest productivity in Eucalyptus grandis. These findings have important implications for marker-assisted tree breeding.     

Age–age and trait–trait correlations for <Emphasis Type="Italic">Eucalyptus grandis</Emphasis> Hill ex Maiden and their implications for optimal selection age and design of clonal trials

Previous results from seven locations of Eucalyptus grandis clonal trials in Colombia supported the a priori contention of sub-dividing them into three different environmental zones for testing and deployment. Within these zones, the determination of age-age genetic correlations for both height and mean annual increment (MAI) showed that strong age-age correlations are present for a rotation age of 6 years starting at 3 years age and, thereafter, suggesting this age as appropriate for selection. This biological selection age coincides with an "economical" age for selection based on discounted selection efficiency in perpetuity, considering a range of interest rates between 10% and 20%. High genetic correlations between wood density at 3 years and 6 years as well as the lack of genetic correlation between this trait and growth traits, also favors selection at age 3 and facilitates breeding strategies that consider the utilization of both traits for improvement. A simulation of optimal clonal test designs indicated that by using six locations and six blocks per location in a single-tree plot design, between 80% and 90% of the maximum selection efficiency could be obtained. This type of design allows testing of a large number of genotypes across a reasonable number of locations in a cost-effective manner.     

Methyl jasmonate does not induce changes in Eucalyptus grandis leaves that alter the effect of constitutive defences on larvae of a specialist herbivore

The up-regulation of secondary metabolic pathways following herbivore attack and the subsequent reduction in herbivore performance have been identified in numerous woody plant species. Eucalypts constitutively express many secondary metabolites in the leaves, including terpenes and formylated phloroglucinol compounds (FPCs). We used clonal ramets from six clones of Eucalyptus grandis and two clones of E. grandis x camaldulensis to determine if methyl jasmonate (MeJA) treatment could induce changes in the foliar concentrations of either of these groups of compounds. We also used bioassays to determine if any changes in the performance of larvae of Paropsis atomaria, a chrysomelid leaf beetle, could be detected in treated ramets versus the untreated controls, thus indicating whether MeJA induced the up-regulation of defences other than terpenes or FPCs. We found no significant effects of MeJA treatment on either the foliar concentrations of terpenes and FPCs or on herbivore performance. We did, however, detect dramatic differences in larval performance between Eucalyptus clones, thereby demonstrating large variations in the levels of constitutive defence. Larval feeding on clones resistant to P. atomaria resulted in high first instar mortality and disruption of normal gregarious feeding behaviour in surviving larvae. Histological examination of larvae feeding on a resistant clone revealed damage to the midgut consistent with the action of a toxin. These findings concur with mounting evidence that most evergreen perennial plants lack foliar-induced defences and suggest that constitutively expressed secondary metabolites other than those commonly examined in studies of interactions between insect herbivores and Eucalyptus may be important in plant defence.     

福建省中部地区抗寒速生尾巨桉优株筛选

本文通过自然选择与优势木选择方法,选择了适生性状良好的尾巨桉品种的多个优良单株。根据不同选择标准,筛选出抗寒适生优良单株21株,抗寒速生优势木单株13株;对所选单株采用无性系繁殖方法,利用1000mg/L ABT生根粉处理所选择优良单株的穗条,用营养袋扦插培育无性系种苗,并建立无性系采穗圃和优良单株基因库。     

Genotypic variation in wood properties and growth traits of triploid hybrid clones of Populus tomentosa at three clonal trials

To better understand the genetic control of growth traits (tree height, dbh, and stem volume) and wood properties (basic wood density and fiber length) in triploid hybrid clones of Populus tomentosa, genetic relationships among selected wood properties with growth traits were examined in 5-year-old clonal field trials located in Yanzhou, Gaotang, and Xiangfen, northern China. In total, 180 trees from 10 clones were sampled from the three sites. The site had a moderate effect on basic wood density (BWD), stem wood dry weight (DWT), and tree growth and had a highly significant effect on fiber length (FL) (P?<?0.001). Clonal effects were also significant (P?<?0.05) for all studied traits (except for diameter at breast height (DBH) and stem volume (SV)). Clone × site interaction was significant for all the studied traits except for FL. The estimated repeatability of clonal means for FL (0.91) was higher than for BWD (0.71), DWT (0.62), tree height (0.62), DBH (0.61), and SV (0.55). Intersite genetic correlation estimates indicated that wood properties were more stable than growth traits. Phenotypic correlation estimates between SV and BWD ranged from ?0.29 to ?0.10.     

Cloning and endogenous expression of a Eucalyptus grandis UDP-glucose dehydrogenase cDNA

UDP-glucose dehydrogenase (UGDH) catalyzes the oxidation of UDP-glucose (UDP-Glc) to UDP-glucuronate (UDP-GlcA), a key sugar nucleotide involved in the biosynthesis of plant cell wall polysaccharides. A full-length cDNA fragment coding for UGDH was cloned from the cambial region of 6-month-old E. grandis saplings by RT-PCR. The 1443-bp-ORF encodes a protein of 480 amino acids with a predicted molecular weight of 53 kDa. The recombinant protein expressed in Escherichia coli catalyzed the conversion of UDP-Glc to UDP-GlcA, confirming that the cloned cDNA encodes UGDH. The deduced amino acid sequence of the cDNA showed a high degree of identity with UGDH from several plant species. The Southern blot assay indicated that more than one copy of UGDH is present in Eucalyptus. These results were also confirmed by the proteomic analysis of the cambial region of 3- and 22-year-old E. grandis trees by 2-DE and LC-MS/MS, showing that at least two isoforms are present. The cloned gene is mainly expressed in roots, stem and bark of 6-month-old saplings, with a lower expression in leaves. High expression levels were also observed in the cambial region of 3- and 22-year-old trees. The results described in this paper provide a further view of the hemicellulose biosynthesis during wood formation in E. grandis.     

The efficiency of visual selection in early generations of a potato breeding programme

The efficiency of visual selection in the early generations of a potato breeding programme is examined. Tubers from 571 potato genotypes were scored by four breeders after being grown, from true seed, in a glasshouse and in the field for three consecutive years. The four breeders were in good agreement as to which clones would be selected in any environment. The association between breeders was greatest when the clones were grown in plots in the field. All correlations of breeders' preferences between different environments were significantly greater than zero, but only accounted for a small percentage of the total variation. Selection in both the glasshouse and first clonal year produced a desirable response. However, such selection carried a high cost in terms of losing clones with commercial potential. Comparison of a random sample of clones with ones from the same crosses which had been selected, indicated that selection in the glasshouse and first clonal year was at best random with some suggestion, however, of a negative effect.     

Effects of propagule type on genetic parameters of wood density and growth in a loblolly pine progeny test at ages 10 and 11?years

Nine full-sib families of loblolly pine (Pinus taeda L.) were produced by a 3 × 3 factorial mating design. Rooted cuttings and seedlings of full-sib families were tested together in two field locations. Twelve-millimeter wood increment cores were collected from 10- and 11-year-old test trees. On each of the two sites, there were six blocks and a split-plot design, with propagule type as the whole plot and family as the sub-plot. In addition to the collection of wood samples, height and diameter of 1,600 trees were measured. No significant differences were found between cuttings and seedlings for wood density and growth traits. Significant family variation was found for growth and wood density. Genetic parameters estimated for wood density and growth traits using seedlings and rooted cuttings showed that individual-tree and family heritability estimates from rooted cuttings were similar to or higher than those from seedlings for all traits. Half-sib breeding values for parents were highly correlated based on seedling and rooted cutting estimates for height (0.95) and wood density (0.99) but not for diameter (0.56), which suggests that wood density and height breeding value estimates from rooted cuttings in clonal progeny tests can be estimated by traditional seedling tests, but not for tree diameter.     

Relationship between density and ultrasonic velocity in Brazilian tropical woods

In this study, the effect of density on the velocity of an ultrasonic wave in wood is investigated. The aim of the present study was to analyze the influence of density on the longitudinal velocity of an ultrasonic wave, propagated in the longitudinal direction. Experiments were conducted on 5cm x 5cm x 5cm wood specimens selected from the following species: pinus caribea (Pinus caribea var. caribea), eucalyptus citriodora (Eucalyptus citriodora), eucalyptus grandis (Eucalyptus grandis), cupiúba (Goupia glabra) and jatobá (Hymenaea sp.). The relationship between density and velocity was analyzed in two different manners: between and within species. The results obtained between species indicated that ultrasonic velocity tends to increase with increasing density. The results obtained within species also showed an increasing trend in ultrasonic velocity as density increased, but the relationship was not as significant as it was for between species.     

Proteomic analysis of the cambial region in juvenile Eucalyptus grandis at three ages

Recent advances in genomics and proteomics have provided an excellent opportunity to understand complex biological processes such as wood formation at the gene and protein levels. The aim of this work was to describe the proteins participating in the processes involved in juvenile wood formation by isolating proteins from the cambial region of Eucalyptus grandis, at three ages of growth (6-month-old seedlings, 3- and 6-year-old trees), and also to identify proteins differentially expressed. Using a 2-D-LC-MS/MS strategy we identified a total of 240 proteins, with 54 corresponding spots being present in at least two ages. Overall, nine proteins classified into the functional categories of metabolism, cellular processes, and macromolecular metabolism showed significant changes in expression. Proteins were classified into seven main functional categories, with metabolism representing 35.2% of the total proteins identified. The comparison of the reference maps showed not only differences in the expression pattern of individual proteins at each age, but also among isoforms. The results described in this paper provide a dynamic view of the proteins involved in the formation of juvenile wood in E. grandis.     

Use of mid-parent values and progeny tests to increase the efficiency of potato breeding for combined processing quality and disease and pest resistance

A potato breeding strategy is presented which avoids the common but ineffective practice of intense early-generation visual selection between seedlings in a glasshouse and spaced plants at a seed site. Once pair crosses have been made, progeny tests are used to discard whole progenies before starting conventional within-progeny selection at the unreplicated small-plot stage. Clones are also visually selected from the best progenies for use as parents in the next cycle of crosses whilst they are multiplied to provide enough tubers for assessment of their yield and quality. Mid-parent values, as well as progeny tests, are then used to select between the resultant crosses. Material from other breeding programmes can be included in the parental assessments and used in the next cycle of crosses if superior. Finally, in seeking new cultivars, the number of clones on which to practise selection is increased by sowing more true seed of the best progenies, but without selection until the small-plot stage. Traits considered are resistance to late blight [ Phytophthora infestans (Mont.) de Bary] and to the white potato cyst nematode [ Globodera pallida (Stone)], fry colour and tuber yield and appearance, as visually assessed by breeders. The theoretical superiority of the strategy for seeking new cultivars lies in being able to practise between-cross selection for a number of economically important traits within 1 or 2 years of making crosses, something that is not possible on individuals as seedlings in the glasshouse or spaced plants at the seed site. This also means that full-sib family selection can be operated on a 3-year cycle, an improvement on current practice of clonal selection on what is often at least a nine-year cycle. New cultivars can be sought with more confidence from the best progenies in each cycle, and modern methods of rapid multiplication used to reduce the number of clonal generations required to find the best clones.     

Polymorphisms in cinnamoyl CoA reductase (CCR) are associated with variation in microfibril angle in Eucalyptus spp

Linkage disequilibrium (LD) mapping using natural populations results in higher resolution of marker-trait associations compared to family-based quantitative trait locus (QTL) studies. Depending on the extent of LD, it is possible to identify alleles within candidate genes associated with a trait. Analysis of a natural mutant in Arabidopsis has shown that mutations in cinnamoyl CoA reductase (CCR), a key lignin gene, affect physical properties of the secondary cell wall such as stiffness and strength. Using this gene, we tested whether LD mapping could identify alleles associated with microfibril angle (MFA), a wood quality trait affecting stiffness and strength of wood. We identified 25 common single-nucleotide polymorphism (SNP) markers in the CCR gene in Eucalyptus nitens. Using single-marker and haplotype analyses in 290 trees from a E. nitens natural population, two haplotypes significantly associated with MFA were found. These results were confirmed in two full-sib families of E. nitens and Eucalyptus globulus. In an effort to understand the functional significance of the SNP markers, we sequenced the cDNA clones and identified an alternatively spliced variant from the significant haplotype region. This study demonstrates that LD mapping can be used to identify alleles associated with wood quality traits in natural populations of trees.     

干燥方式对尾巨桉树皮提取物总三萜含量及其杀螺活性的影响

为探讨干燥方式对尾巨桉树皮提取物总三萜含量的影响和其杀螺作用机理,实验以尾巨桉树皮为研究对象,比较鼓风干燥和冷冻干燥两种干燥方式对其树皮乙醇提取物总三萜含量及杀螺活性的影响。结果表明,当乙醇体积分数为60%时,鼓风干燥和冷冻干燥的尾巨桉树皮乙醇提取物中总三萜含量最高,分别为10.81%和13.90%。两种干燥方式得到的尾巨桉树皮乙醇提取物对福寿螺均有较强的毒杀活性,在50mg/L的浓度下处理72h,福寿螺的死亡率分别到达93.1%和100.00%;同时尾巨桉树皮提取物还能显著抑制福寿螺离水上爬,抑制效果优于同浓度下的对照药剂茶皂素(P<0.05)。与空白对照组相比,经鼓风干燥的尾巨桉树皮提取物处理后,福寿螺头足和肝脏的蛋白质含量变化不大(P>0.05);经过冷冻干燥的尾巨桉树皮提取物处理后,福寿螺头足中蛋白质含量显著降低(P<0.05),而肝脏中蛋白质含量无明显变化(P>0.05)。鼓风干燥和冷冻干燥的尾巨桉树皮提取物均可有效抑制福寿螺头足部中LDH、AKP和AST/GOT的活性(P<0.05)以及肝脏中ALT/GPT和AST/GOT的活性(P<0.05)。冷冻干燥的尾巨桉树皮提取物中三萜含量以及杀螺活性均高于鼓风干燥的树皮提取物。     

Interspecific hybridization of Eucalyptus as a potential tool to improve the bioactivity of essential oils against permethrin-resistant head lice from Argentina

The essential oils extracted from Eucalyptus grandis, Eucalyptus camaldulensis, Eucalyptus tereticornis, and the hybrids E. grandisxE. camaldulensis, and E. grandisxE. tereticornis were analyzed by GC-MS, and evaluated for their fumigant and repellent effects on permethrin-resistant head lice. Fumigant activity of both hybrids was higher than that for pure species. E. grandisxE. tereticornis and E. grandisxE. camaldulensis showed KT50 values of 12.99 and 13.63min, respectively. E. grandis, E. camaldulensis, and E. tereticornis showed KT50 values of 25.57, 35.01, and 31.31, respectively. A simple regression analysis revealed a significant correlation between KT50 data and % of 1,8-cineole in these essential oils. Repellency varied from 47.80+/-16% to 80.69+/-6% for the five Eucalyptus essential oils tested. Interspecific hybridization improves the pediculicidal activity of Eucalyptus essential oils.