Early recognition of graft compatibility in <Emphasis Type="Italic">Uapaca kirkiana</Emphasis> Müell Arg. clones,provenances and species

Examination of callus micro-grafts in Uapaca kirkiana Müell Arg. was carried out with the objective of determining early signs of graft compatibility. Leaves from U. kirkiana, U. nitida and Jatropha curcas trees were used for callus induction. Two pieces of callus were co-cultured on Murashige and Skoog (MS) medium with different supplements. Co-cultured calli were embedded in paraffin wax and dissected. The specimens were stained in safranin and fast green before viewing under a light microscope. Results showed that MS medium with 0.1 mg l⁻¹ thidiazuron (TDZ) and 0.5 mg l⁻¹ naphthaleneacetic acid (NAA) or 1.0 mg l⁻¹ dichlorophenoxyacetic acid (2,4-D) and 0.5 mg l⁻¹ NAA was effective for callus induction. There were no necrotic layers at the unions within U. kirkiana clones and provenances, but a differential growth (irregularity) between U. kirkiana and U. nitida co-cultured calli. Phenol deposits were observed at the union interfaces of U. kirkiana combinations and were high on calli derived from mature trees. Phenol deposits were absent at the union of J. curcas heterografts. Necrotic layers developed at the unions of U. kirkiana and J. curcas micro-grafts and indicating an outright graft incompatibility. Accumulation of phenol deposits at the union interfaces inhibited graft compatibility in many U. kirkiana combinations. Callus fusion technique can be used to identify partners with an outright graft incompatibility, especially for distant related plant species.     

Detection of differential changes in lignin composition of elm xylem tissues inoculated with Ophiostoma novo‐ulmi using Fourier transform‐infrared spectroscopy

Differences in elm susceptibility against Ophiostoma novo‐ulmi have been related with differences in timing and degree of the tree defence responses. In this study, we used Fourier transform‐infrared spectroscopy, coupled with chemometric methods, to detect progressive changes in the metabolic profile of Ulmus minor and U. minor × U. pumila xylem tissues after inoculation with O. novo‐ulmi. Differences between control and inoculated trees were detected at 30 and 60 days post‐inoculation (dpi) in U. minor, and at 15, 30 and 60 dpi in U. minor × U. pumila. These differences were related with increased levels of lignin in the xylem tissues, suggesting an earlier defence response to the infection in the hybrids.     

Metabolic fingerprinting allows discrimination between Ulmus pumila and U. minor,and between U. minor clones of different susceptibility to Dutch elm disease

Experiments were conducted to test whether Fourier transform‐infrared (FT‐IR) spectroscopy, coupled with chemometric methods, can distinguish healthy xylem tissues collected from elms known to differ significantly in their susceptibility to Ophiostoma novo‐ulmi Brasier. Twig samples from resistant Ulmus pumila L., susceptible U. minor Mill. and resistant U. minor clones were harvested on 1 May, 15 May, 1 June, 1 July and 1 September 2004, and subjected to FT‐IR analysis. The application of principal component analysis to the spectral data, followed by discriminant function analysis, discriminated between the three groups of samples in all harvesting dates. The examination of the DF‐loading plots allowed the identification of key regions within the spectra for the separation between clusters. The chemical assignments of these key regions allowed the following interpretations to be made: (i) U. pumila tissues contained enhanced levels of starch, cellulose and lignin with respect to U. minor tissues and (ii) resistant U. minor tissues contained enhanced levels of starch, cellulose and pectic polysaccharides with respect to susceptible U. minor tissues. The possible roles of the compositional differences in disease resistance, as well as the potential use of FT‐IR spectroscopy and chemometrics as a tool for screening resistant elms are discussed.     

Effects of nutrient availability on performance and mortality of <Emphasis Type="Italic">Rumex obtusifolius</Emphasis> and <Emphasis Type="Italic">R. crispus</Emphasis> in unmanaged grassland

Several authors record high mortality of the weedy species Rumex obtusifolius in unmanaged grasslands, but there have never been any studies on how the performance and mortality of R. obtusifolius and R. crispus are affected by different nutrient availability in unmanaged temperate grasslands. To investigate this question, we established a seedlings transplantation and fertiliser experiment on unmanaged Dactylis glomerata grassland in Czech Republic. We monitored plant height, number of leaves per plant, fertility and mortality of transplanted R. obtusifolius and R. crispus plants, from 2008 to 2011, in an unfertilised (U) and a fertilised (F) treatment (manure applied in 2008 at the rate of 200 kg of nitrogen, 42 kg of phosphorus and 230 kg of potassium per ha). In 2010, taller plants of both species were recorded in treatment F than in treatment U, but there was no effect of treatment on the number of leaves. In 2010, fertility for both species was 50% in treatment F, but only 20% for R. obtusifolius and 10% for R. crispus in treatment U. Over 4 years, no mortality of R. obtusifolius in treatment F contrasted with 30% mortality in treatment U. In the case of R. crispus, mortality was 50% in treatment F and 28% in treatment U. An increase in nutrient availability can decrease mortality of R. obtusifolius plants in grasslands, but increase mortality of R. crispus. It seems that leaving grassland unmanaged for several years is only an effective strategy for control of R. obtusifolius under conditions of low nutrient availability.     

First report on the Dutch elm disease pathogen Ophiostoma novo‐ulmi from Latvia

During 2017, Dutch elm disease was investigated on 67 Ulmus glabra and 29 Ulmus laevis samples from 28 sites in Latvia. The presence of Ophiostoma novo‐ulmi was detected in 61.2% of the samples from U. glabra and in 34.5% of the samples from U. laevis. In 11% of cases, hybrids between subsp. novo‐ulmi and subsp. americana were identified, particularly in the sites in the southern part of Latvia. This study presents the first verified record of Ophiostoma novo‐ulmi and its subspecies in Latvia.     

An artificial inoculation protocol for Uromycladium acaciae,cause of a serious disease of Acacia mearnsii in southern Africa

Uromycladium acaciae is the cause of a severe wattle rust epidemic in plantations of Acacia mearnsii (black wattle) in southern Africa. Research on the biology of this damaging rust is assisting in the development of control strategies. One strategy under investigation is the identification and deployment of resistant lines of A. mearnsii. Selection of resistant families currently relies on large-scale, time-consuming and expensive field trials. In this study, we present a detailed artificial inoculation protocol for U. acaciae, which can be used to screen for resistance. The results of an experiment that used the protocol to screen the relative resistance of 12 families of A. mearnsii to U. acaciae are also presented. The developed artificial inoculation protocol can also be used to investigate several other aspects of this host–pathogen system.     

白榆研究利用现状及我国白榆良种化探讨与展望

白榆（Ulmus pumila）是我国分布最广、最重要的榆属树种,具有重要的经济和生态价值。然而,由于人们对白榆优良性状认识不足,近年来白榆在科研和生产等方面都未受到应有的重视。文中介绍了白榆资源地理分布情况及其生物学特性,综述了白榆研究（不同自然类型、遗传结构特性、扦插组培快繁、逆境生理响应、病虫害防治和天然活性成分分析）、利用（生态防护、用材、园林观赏和药用等）和我国白榆良种选育（种子园建设及种子区划、选择育种和杂交育种）的现状,提出了我国白榆推广应用的良种化建议,并对白榆未来的研究进行了展望,以期为进一步提升白榆的研究水平、提高白榆利用的生态和经济效益提供参考。     

尾叶桉与赤桉正反析因交配杂种F_1材性遗传参数的估算

[目的]通过尾叶桉与赤桉杂种F1材质性状的遗传参数估算及其分析,为桉树杂交育种材性改良亲本选配和交配设计提供理论依据。[方法]以尾叶桉与赤桉6×6正反析因交配杂种F1测定林为材料,并以相应亲本自由授粉的半同胞子代作对照。9年生时,对各小区的杂种和家系(5株小区,6次重复)选取2株平均木,在胸高1. 3 m处沿南北向钻取木芯,共984个,测定木材基本密度、纤维长、纤维宽和纤维长宽比,利用ASReml-R估算4个材质指标的特殊配合力、杂种优势、父母本单株狭义遗传力、遗传相关和表型相关系数。[结果]表明:尾叶桉与赤桉正反交的杂种木材基本密度优于对照,呈明显的杂种优势;反交组合杂种其木材基本密度优于正交组合杂种,正交组合杂种的纤维特性优于反交组合的;在正交组合杂种中,木材基本密度、纤维长和纤维长宽比的母本效应低于父本效应;而反交组合杂种中,4个材质指标的母本效应均高于父本效应。木材基本密度和纤维特性指标受中至低遗传控制。正反交组合杂种中,除纤维长宽比外,其余3个材质指标的显性效应大于加性效应。对于遗传相关,杂种的木材基本密度与纤维宽呈极显著的负相关,与纤维长宽比呈极显著的正相关,与纤维长呈不显著负相关,纤维长与纤维宽呈显著正相关。对于表型相关,除纤维宽与纤维长宽比呈不显著正相关外,其余性状间均呈极显著正相关。[结论]尾叶桉与赤桉杂种的材质性状遗传差异因亲本和交配方式而异,表明通过种间杂交和正向选择进行材质性状的遗传改良具有潜力。     

外源水杨酸对盐胁迫下白榆生理特性的影响

目的]以白榆幼苗为材料,研究不同浓度水杨酸(SA)的喷施对盐胁迫下白榆生理代谢的影响。[方法]以1年生白榆品种‘白洼一号’幼苗为材料,在0、50、100和150 mmol·L~(-1)Na Cl浓度下,喷施不同浓度SA(0、0.5、1.0、2.0 mmol·L~(-1)),处理30 d后对白榆水分生理、膜脂过氧化、光合色素含量和光合气体交换参数进行测定。[结果]表明:(1)盐胁迫下,外源SA可以显著提高白榆叶片相对含水量、可溶性糖含量,并降低丙二醛含量,但对电解质渗透率影响不显著。(2)0.5和2.0 mmol·L~(-1)SA会显著提高50和100 mmol·L~(-1)Na Cl胁迫下白榆叶片的光合色素含量,1.0 mmol·L~(-1)SA对各盐浓度下光合色素含量改善作用均不明显。(3)2.0 mmol·L~(-1)SA的添加提高了盐胁迫下白榆光合气体交换参数,1.0 mmol·L~(-1)SA明显降低了50 mmol·L~(-1)盐浓度下白榆叶片的净光合速率和气孔导度。[结论]适宜浓度的SA能改善白榆的生理参数,隶属函数法综合评价表明:0.5和2.0 mmol·L~(-1)SA对盐胁迫下白榆生理参数的改善作用较明显。     

Variation among Italian and French elm clones in their response to Ophiostoma novo‐ulmi inoculation

In 1995 a clone bank of elms from across Italy was created at Antella (Florence, I) under a European Union project. In 1998 an experimental planting of some clones from this source was established in Antella together with material from a similar clone bank in France and two reference clones: Commelin (relatively susceptible) and Lobel (relatively resistant). In May 2001, the elms were inoculated with Ophiostoma novo‐ulmi and disease development was assessed throughout that summer and the next. Significant differences in susceptibility were found between taxonomic groups, with putative natural hybrids between Ulmus minor and Ulmus pumila being the most resistant and Ulmus glabra the most susceptible. Significant differences were also found within U. minor, some clones being as resistant as Lobel. For U. minor, a statistically significant relation was found with latitude, southerly clones showing less disease than more northerly ones. Relationships were also found between disease severity and times to bud burst, these relationships applying both to the different taxonomic groups and within U. minor. Relationships between growth increment and disease severity were inconsistent. These results are discussed in relation to the intrinsic genetically‐controlled differences that exist between elms and to differences in susceptibility that occur as the growing season proceeds and as a consequence of environmental influences.     

Studies on hypersaline-tolerant white-rot fungi III: biobleaching of unbleached kraft pulp by hypersaline-tolerant manganese peroxidase from a marine white rot isolate, <Emphasis Type="Italic">Phlebia </Emphasis>sp. MG-60

 A marine white rot isolate, Phlebia sp. MG-60, secreted lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase under different sea salt incubation conditions. Its MnP production was strongly enhanced by adding 3% sea salts, and the MnP showed high tolerance to sea salts and NaCl. The crude enzyme secreted at 3% sea salt concentration by Phlebia sp. MG-60, in which the main component was MnP (cMnP), was then used to bleach unbleached hardwood kraft pulp (UKP) in vitro. The pulp was brightened 11 points by 4 U of cMnP, and the kappa number was decreased 6 points when only 0.5 mM H₂O₂ was added continuously. When 0.5 mM H₂O₂ (1.22 mg H₂O₂ /g pulp) was added at the initial bleaching, the pulp brightness increased 6 points with a dosage of 4 U of cMnP. When crude MnPs were employed to bleach UKP with organic-free model white-water instead of the Milli Q water usually used, the pulp was brightened 10 and 13 points by 4 and 20 U of cMnP, respectively, and 5 and 6 points by 4 and 20 U of MnP, respectively, of Phanerochaete chrysosporium. Received: September 28, 2001 / Accepted: March 15, 2002 Correspondence to:R. Kondo     

Cost-benefit analysis of wood and food components of agri-silviculture in Nigerian forest zone

Costs and revenue of agri-silviculture in Nigerian forest zone were estimated. Two crop combinations were considered: Gmelina arborea Roxb., a hardwood species was interplanted with (a) yam (Dioscorea rotundata) and maize (Zea mais) and (b) cassava (Manihot utilissima) and maize. Agri-silviculture increases the farmer's income in this zone. The ratios of total cost to revenue are 1:2.3 for yam and maize and 1:2.4 for cassava and maize. The farmer's net income is U.S. $4065.86 from yam and maize and U.S. $2790.24 from cassava and maize. When the trees are clear-cut after five years, the ratio of cost to revenue is 1:2.4. The farmer's net income from wood is U.S. $2872.95. If 5 per cent of the farm families in the area practices agri-silviculture, each family cultivating one hectare, there will be enough fuelwood after five years' growth.     

Resistance to amitraz in the parasitic honey bee mite Varroa destructor is associated with mutations in the β-adrenergic-like octopamine receptor

Varroa destructor is considered a major reason for high loss rate of Western honey bee (Apis mellifera) colonies. To prevent colony losses caused by V. destructor, it is necessary to actively manage the mite population. Beekeepers, particularly commercial beekeepers, have few alternative treatments other than synthetic acaricides to control the parasite, resulting in intensive treatment regimens that led to the evolution of resistance in mite populations. To investigate the mechanism of the resistance to amitraz detected in V. destructor mites from French and U.S. apiaries, we identified and characterized octopamine and tyramine receptors (the known targets of amitraz) in this species. The comparison of sequences obtained from mites collected from different apiaries with different treatment regimens, showed that the amino acid substitutions N87S or Y215H in the OctβR were associated with treatment failures reported in French or U.S. apiaries, respectively. Based on our findings, we have developed and tested two high throughput diagnostic assays based on TaqMan technology able to accurately detect mites carrying the mutations in this receptor. This valuable information may be of help for beekeepers when selecting the most suitable acaricide to manage V. destructor.

     

Effect of salt stress on activity of superoxide dismutase （SOD） in Ulmus pumila L.

The injury tolerance of cell plasma membrane and the correlative enzymes activities of plasma-membrane protection system in the Ulmuspumila leaves treated by nine concentrations （0.3%, 0.6%, 0,9%, 1,2%, 1.5%, 1.8%, 2,1%, 2.4%, 3.0%） of Na2CO3 and NaHCO3 mixtures were studied in a greenhouse of Northeast Forestry University, Harbin, China. The rate of electrolyte leakage （REL） and SOD （Superoxide dismutase） activity in leaves of different samples were determined. Results showed that the REL in leaves of U. pumila presented a slowly increasing trend at the salt concentrations less than 1.5%, which indicated that cell plasma membrane of U. pumila leaves had rather strong resistance to the injury of salt ion, and had a significant increase at the salt concentrations more than 1.5%. The SOD activities in leaves of U, pumila presented an increased trend at salt concentrations less than 1.5%, the growth of seedlings did not decline, and tress and leaves had no symptom of injury, while the salt concentrations exceeded 1.5%, SOD activities sharply decreased and REL increased promptly.     

First report of Ceratocystis huliohia causing mortality of Metrosideros polymorpha trees on the Island of Kauaʻi,Hawaiʻi USA

The fungus Ceratocystis huliohia was detected for the first time in dead and dying Metrosideros polymorpha trees on the Island of Kaua?i, Hawai?i, U.S.A. Fungal isolates were recovered from diseased trees into culture, and identities were confirmed by diagnostic qPCR assay and DNA sequencing. Growth chamber inoculations confirmed C. huliohia pathogenicity on M. polymorpha seedlings and subsequently the same fungus was recovered, completing Koch's postulates. DNA sequence analysis revealed a unique ITS haplotype for Kaua?i isolates of C. huliohia that has not been found on Hawai?i Island.     

Ulocladium chartarum as the causal agent of a leaf necrosis on Quercus pubescens

Summary A necrosis of leaves of Quercus pubescens caused by the fungus Ulocladium chartarum is reported. This fungus causes leaf spots both under natural conditions and following artificial inoculation of unwounded attached leaves. A high incidence of leaf spotting by U. chartarum seems to be associated with wet summers.     

Differentiation of seed germination traits in relation to the natural habitats of three <Emphasis Type="Italic">Ulmus</Emphasis> species in Japan

Germination traits of three Japanese Ulmus species, including two summer-fruiting species, U. davidiana var. japonica (UD) and U. laciniata (UL), and an autumn-fruiting species, U. parvifolia (UP), were investigated. Germination tests that controlled light (16 h dark–8 h light/24 h dark) and temperature (alternating 20–30°C/constant 23°C) conditions were conducted just after seed dissemination. Under the preferred (light and alternating temperature) conditions, UD germinated quickly and percentage germination was high (99%), whereas UL and UP germinated moderately to slowly (65.2 and 23.8%, respectively) and the remaining seeds were primarily dormant. When the seeds were exposed to unsuitable conditions for germination, secondary dormancy was induced in all three Ulmus species. Because primary and secondary dormancy of these species was not strict, the existing dormancy could be released by moist conditions and low temperature during the winter. Thus, all three Japanese Ulmus can germinate either just after seed dissemination or in the following spring. Nevertheless, the predominant germination of summer-fruiting UD just after seed dissemination seems to be advantageous for finding safe sites that might become available after a large-scale fluvial disturbance. Similarly, the delayed germination of autumn-fruiting UP until the following spring seems to be advantageous for preventing germination at the end of the growing season. Summer-fruiting UL had a more negative response to favorable light conditions just after seed dissemination, which seems to be advantageous for establishment in canopy gaps. These germination traits seem to be adaptive responses to the dominant disturbance regimes of their natural habitats.     

Stem cankers of young Douglas-firs associated with larval feeding galleries of Laspeyresia pseudotsugae (Lepidoptera: Olethreutidae

The feeding galleries of lepidopterous larvae (Laspeyresia pseudotsugae Evans) in bark of young Douglas-fir were extensively cankered, resulting in permanent damage to the trees. The chief fungus associated with the cankering was Pragmopora pithya [(Fr.) Fr.] Groves. The damage occurred in plantations on Vancouver Island and adjacent mainland of British Columbia, Canada and Washington, U.S.A.     

Dieback and decline of wild almond (Amygdalus scoparia Spach) in the Harat protected forest of Yazd Province,Iran

Wild almond (Amygdalus scoparia) is a dominant shrub species in mountain forests of the Irano‐Turanian region. Dieback and decline symptoms of wild almond shrubs were first observed in Harat protected forest (Yazd, Iran) in the autumn of 2014. Since then, the incidence and severity of the disease have increased. To study the aetiology and estimate losses from the disease, field studies were conducted in 2016 and 2017. For this purpose, eight stands were selected, in which 24%–99% of the trees were wild almond in their species composition. In total, 50 cankers and 50 infected twigs of wild almond shrubs were collected. Fungal isolates were identified based on morphological and cultural characteristics, as well as sequence data of ITS1 + 5.8S + ITS2 rDNA. Pathogenicity of fungi was checked on detached shoots and evaluated after 40 days by measuring the discoloured lesion length at the inoculation site. Among 681 wild almond shrubs checked, 84.44% showed decline symptoms with different severities; only 15.56% did not show observable disease symptoms. The most frequent colonizers of infected tissues taken from cankers were Wilsonomyces carpophilus (56%), Thyrostroma cornicola (40%) and Collophorina paarla (30%). Infected twigs were extensively colonized by W. carpophilus (36%), Th. cornicola (24%) and Ulocladium consortiale (24%). Other species, such as Endoconidioma populi, Microsphaeropsis olivacea, Trichoderma asperellum, Paecilomyces formosus, Saccothecium rubi, Preussia sp. and Chaetomium globosum, had lower isolation frequencies. W. carpophilus, Th. cornicola, C. paarla and U. consortiale were found as pathogens on detached wild almond shoots. Based on the frequency of the isolates and the pathogenicity tests, four fungi, such as W. carpophilus, Th. cornicola, C. paarla and U. consortiale, are considered serious contributing agents playing a significant role in the dieback and decline of wild almond. All isolated species are reported for the first time on the wild almond shrubs of the world.     

Non-additive Effects of Leaf Litter Mixtures from Robinia pseudoacacia and Ten Tree Species on Soil Properties

ABSTRACT

Litter decomposition plays a critical role in both nutrient cycling and the interspecific relationships between tree species. In this study, leaf litter from Robinia pseudoacacia was mixed with litter from 10 other species, this mixture was then ground and incubated in soil. The soil indexes (i.e., quantity of microbes, activities of enzymes, and chemical properties) were analyzed to study the effects of litter decomposition on soil properties and the interaction between the litters. If mixed separately with Larix principis-rupprechtii or Betula platyphylla, R. pseudoacacia litter exerted synergistic effects on the activities of most enzymes. The mixed litters of R. pseudoacacia and Pinus sylvestris var. mongolica or Ulmus pumila exerted synergistic effects on the soil available P. With regard to the soil properties as a whole, the mixed litters of R. pseudoacacia and B. platyphylla, Pinus tabulaeformis, P. sylvestris var. mongolica, or L. principis-rupprechtii exerted synergistic effects on soil during their decomposition. However, the mixed litters of R. pseudoacacia and Populus simonii, Quercus liaotungensis, U. pumila, or Caragana microphylla did not. This indicated that R. pseudoacacia mixed with the litter of other needle-leaf tree species benefits the development and regeneration of soil and thus can be used for sustainable forest management.