Über das Vorkommen von Armillaria-Arten und-Klonen in benachbarten Koniferenbeständen,Mischbeständen und in Laubwald1

Occurrence of species and clones of Armillaria in spruce stands, mixed stands and hardwood stands in close neighbourhood . From Armillarid rhizomorphs (collected around trees) and from spruce butt rots, isolates of the diploids were made. In pairings between the diploid isolates and haploid testers from the five (European) biological species (BULLER phenomenon) the mating reactions often were not clear enough to identify the diploids. So carpophores were raised from the isolates and single spore cultures were obtained. In pairings with the haploid testers Armillaria borealis, A. bulbosa and A. bulbosa were identified. Usually more than one Armillaria species and from each species more than one clone occurred in each stand.     

Comparaison de deux méthodes d'identification des clones chèz le Basidiomycete parasite Armillaria obscura (syn: A. ostoyae)

Two methods were compared intending to distinguish between the clones of the root-rot fungus Armillaria obscura (syn. Armillaria ostoyae) in nature: one based on the pairing of the diploid isolates in pure culture, the other using the incompatibility alleles as genetic markers. As A. obscura fruits easily in vitro, both methods could be used for any type of diploid isolate whatever its origin. The two methods were quite superposable and defined the same clones. Artificial diploids issuing from the same fruitbody and isogenic for the incompatibility alleles appeared to belong to the same clone in pairing tests.     

Mycelial fan formation of three sympatric Armillaria species on excised stem segments of Picea abies

Mycelial fan formation was studied in five Armillaria cepistipes, ten A. borealis and ten diploid and six haploid A. ostoyae strains on excised stem segments of Picea abies. Stem segments were either non‐autoclaved or autoclaved, representing dying and dead wood, respectively. To confirm the identity of mycelial fans on non‐autoclaved stem segments, re‐isolations were made and isolates characterized with microsatellite markers. Mycelial fan formation on autoclaved stem segments was fast and reliable for most of the tested Armillaria strains. On non‐autoclaved stem segments, mycelial fan formation was slower, more erratic and less predictable. Mycelial fan formation was fastest in A. cepistipes closely followed by A. borealis and was slowest in A. ostoyae. For two A. cepistipes and four A. ostoyae strains (all diploid), growth rates of mycelial fans were estimated in a time course experiment. They ranged between 5.1 and 8.7 mm/day for autoclaved and between 1.4 and 4.7 mm/day for non‐autoclaved stem segments. The haploid A. ostoyae strains also formed mycelial fans on autoclaved stem segments, but typically slower and less reliably than the diploid strains. Whether haploid strains are able to produce mycelial fans on non‐autoclaved stem segments remains unknown because of accidental diploidization of the original haploid strains which was likely caused by basidiospores introduced into the study system on the non‐autoclaved stems. Overall, the method developed in this study may be useful for further investigations into the genetic, physiological and biochemical nature of mycelial fan formation in the genus Armillaria.     

滇杨多倍体苗期叶片形态及光合生理比较分析

[目的]以前期研究诱导获得的滇杨种质为试验材料,比较分析其苗期叶片形态及光合生理与基因剂量的关系,为滇杨多倍体育种提供理论指导。[方法]利用前期研究所获得的滇杨多倍体当年生苗为材料,测定其叶片大小、叶片厚度、栅栏组织厚度、气孔特性及叶绿素含量,并以滇杨二倍体为对照,分析滇杨不同程度多倍化后的叶片形态及光合生理特性。[结果]表明:嵌合体及四倍体滇杨的叶片长、宽均大于二倍体植株;滇杨嵌合体及四倍体叶片厚度分别为二倍体的1.16、1.41倍,栅栏组织厚度分别为二倍体的1.10、1.23倍,叶片单位视野内气孔数明显少于二倍体,气孔体积则大于二倍体,叶绿素总含量分别为二倍体的127%和141%;滇杨嵌合体及四倍体植株的净光合速率在日变化过程中均高于二倍体;气孔导度、蒸腾速率则与二倍体差别较小;嵌合体、四倍体及二倍体的胞间CO₂浓度在日变化过程中变化不明显。 [结论]滇杨多倍化后,由于其基因数量的增加,在叶片形态及光合生理特性等方面,表现出了明显区别于其二倍体的剂量效应。     

Differences in the rust resistance of greenhouse and outdoor-grown white birch species,Betula spp.

The 2-year-old seedlings of five different white birch species (Betula platyphylla, Betula papyrifera, Betula pubescens, Betula pendula (two types) and Betula resinifera x Betula pendula) grown both in a greenhouse and outdoors, were inoculated in a leaf disc assay with two different birch rust (Mel-ampsoridium betulinum) isolates from B. pendula and B. pubescens. The resistance of these birch species varied significantly. Resistance to the B. pubescens rust isolate was not related to the resistance of the B. pendula rust isolate. The behaviour of a birch genotype grown in the greenhouse did not correspond to the behaviour of the same genotype grown outdoors. The outdoor growth environment greatly increased the contents of soluble proteins, rubisco, chloro-phyll and nitrogen in the leaves of diploid birch species (B. platyphylla, B. pendula and B. resinifera x B. pendula). For tetraploid and pentaploid species (B. pubescens and B. papyrifera, respectively) there was no such clear difference in the leaf physiological status between the seedlings grown outdoors and in the greenhouse. The C:N ratio was higher for the greenhouse-grown seedlings in all the birch species, but the difference was significant only with the diploid species. The incidence of rust in the birch species did not correlate with any of the leaf physiological parameters studied. The adaptability of birch genotypes to the environment in relation to their resistance to birch leaf rust is discussed.     

Secondary metabolites from dual cultures of genetically different Armillaria isolates

Toxic secondary metabolites are synthesized for attack or defence in competing cultures of different basidiomycete species. In combination with incompatibility reactions changes in the pattern of secondary metabolites were also detected in dual cultures of diploid isolates of different Armillaria species (Armillaria gallica, Armillaria borealis and Armillaria cepistipes) on agar. In dual cultures the response in A. cepistipes was most pronounced and occurred combined with increasing growth inhibition of the fungus. The toxic metabolites which were formed in monocultures disappeared and the newly arising metabolites showed no antibiotic activity. The chemical structures of the compounds have been elucidated (two are described for the first time) as sesquiterpene esters of orsellinic acid derivatives. The augmenting metabolites of A. cepistipes are dehydroxylation products. A new facet of the role of secondary metabolites in the ecological interactions of fungi is described, namely, the detoxification of toxins by a competitor.     

The Role of Rhus trichocarpaMiq. Patches in Pine Forest Dynamics in Japan

Abstract

Rhus trichocarpaMiq. is a short-statured pioneer tree species that creates patch communities during the early successional stages of some pine forests in Japan. A 0.6 ha sample plot was established in a Japanese red pine (Pinus densifloraSieb, et Zucc.) stand to evaluate the influence of patch structure on regeneration of R. trichocarpaand other tree species. The plot included 47 patches of R. trichocarpa.The survivorship of R. trichocarpaseedlings was high in small patches, but low in large ones. The small patches expanded, transforming into large ones over several years. Several tree species such as Quercus serrataThunb., Primus apetalaFranch. et Sav., Sorbus commixiaHedl., and Magnolia obovataThunb. invaded the patches after the fruiting of R. trichocarpa.They grew faster than R. trichocarpain these patches and broke through the R. trichocarpacrown layer after about 10 years.

The fruits of R. trichocarpaattract birds which disperse seeds produced by other tree species. Thus, the R. trichocarpapatch plays a vital role in changing from pioneer tree species to shade-tolerant tree species.     

Distribution,hybridisation and morphological variation in Alnus rohlenae (Betulaceae) an endemic species of the Balkan Peninsula

The diploid A. glutinosa (L.) Gaertn. is widespread throughout the European continent, except in the Iberian and Balkan Peninsulas where tetraploid populations have been discovered. We focused on the tetraploid species described as A. rohlenae Vít, Douda and Mandák that occupies the western part of the Balkan Peninsula, where it has likely completely replaced the diploid species. While the distribution range of the diploid A. glutinosa s. str. is well known, the exact distribution range of the tetraploid A. rohlenae is unknown. Here, we report the first exact distribution of the tetraploid A. rohlenae and the anticipated hybrid zones in which it is in contact with diploid populations using flow cytometry and morphometrics. Tetraploids are located primarily in the mountainous parts of the study area and towards the lowlands are gradually being replaced by diploids, forming a contact zone. We compare the main morphological characteristics of both species. Due to the geographical proximity of the study species, the morphological differences between them are clear outside the contact zones. However, within the contact zones, we recorded hybridisations that obscure the morphological differences between species, probably due to the presence of triploid hybrids.

     

Microclimate and nutrient dynamics in a silvopastoral system of semiarid northeastern Brazil

There is little available information on nutrient cycling and the controls of ecosystem processes in land use systems of dry neotropical regions. In this study, we conducted field and glasshouse experiments to investigate the influence of Ziziphus joazeiro and Prosopis juliflora trees on microclimate and nutrient dynamics in pastures ofCenchrus ciliaris in semiarid northeastern Brazil. We found that soil moisture was lower under the crowns of P. juliflora trees during early season in comparison to patches ofC. ciliaris (grass patches), but the presence of Z. joazeiro had no effect on soil moisture. Soil and air temperatures were lower under Z. joazeiro in comparison to grass patches but P. juliflora had little effect on temperature. Losses of P from all litter types were lower under the crowns of Z. joazeiro trees, but losses of biomass and N from litter were not consistently affected by the presence of trees. Soil net N mineralized was greater under both tree species, in comparison to grass patches. However, net soil N mineralized per gram of total soil N was greater under the crowns of the potentially N₂ fixing P. juliflora, in comparison to grass patches, while there were no significant differences betweenZ. joazeiro crowns and grass patches. In the glasshouse study, plant biomass and nutrient uptake was greater in soil collected under the crowns of both tree species, in comparison to soil from grass patches. Our results indicate that the preservation of native trees or introduction of exotic tree species in C. ciliaris pastures in semiarid northeastern Brazil significantly affects microclimate and the dynamics of litter and soil nutrients, and may contribute to increases in the cycling rate of nutrients in these systems. Index terms: buffel grass, caatinga, nitrogen mineralization, Prosopis juliflora, Ziziphus joazeiro.This revised version was published online in November 2005 with corrections to the Cover Date.     

Armillaria species in Japan identified by isozyme patterns with special reference to the biological species of the northern hemisphere

Isozyme patterns were examined to characterize biological species ofArmillaria in Japan. Of 25 different enzymes tested, glutamate dehydrogenase (GDH), lactate dehydrogenase (LDH), and aspartate aminotransferase (AAT) showed the most stable and reliable activities. These isozyme patterns showed little variability between haploid and diploid hyphae even under different cultural conditions among isolates tested. From the results, six Japanese biological species were clearly characterized through combination of GDH and LDH isozymes. There were no differences on the whole in isozyme patterns among European biological species ofArmillaria.     

Investigation of anti-salt stress on tetraploid Robinia pseudoacacia

Tetraploid Robinia pseudoacacia was used as a main test material and diploid R. pseudoacacia was used as the control. The indices of shape, physiology and biochemistry, photosynthesis and anatomic structure of the young plants were investigated under salt stress (NaCl and Na₂SO₄). The treatment time was 30 d with an interval time of 7 d. Before and after treatment, the indices were measured. Results show that: 1) the growth of diploid R. pseudoacacia inhibited an evident symptom of salt damage and the leaf moisture content was lower under salt stress than that of control. But the tetraploid R. pseudoacacia was contrary. 2) The relative electric conductivity and proline (Pro) of tetraploid R. pseudoacacia increased slightly and had no significant difference compared with its control, which was contrary to diploid R. pseudoacacia. At the same time, three protective enzymes including perocidase (POD), superoxide (SOD) and catalase (CAT) kept higher activities at a post stage of salt stress to tetraploid R. pseudoacacia, which enhanced its anti-salt characteristics. Diploid R. pseudoacacia was sensitive to salt and had contrary information. 3) Salt stress had little influence to photosynthesis of tetraploid R. pseudoacacia. The net photosynthetic rate (P _n) and intercellular CO₂ concentration (C_i) had no significant changes, but those of diploid R. pseudoacacia decreased singificantly. 4) After salt stress, the anatomic structure of tetraploid R. pseudoacacia had a positive reaction, including the palisade parenchyma of diachyma, was prolonged and arranged more tightly. The spongy parenchyma was shrunk and was arranged tightly, which was contrary with diploid R. pseudoacacia. These data demonstrate that tetraploid R. pseudoacacia had superior anti-salt performance. __________ Translated from Journal of Plant Ecology, 2008, 32(3): 654–663 [译自: 植物生态学报]     

Effects of Disturbances on Large Patch Formation of Magnolia obovata,A Deciduous Broad-Leaved Tree-Field Investigation and Simulation

Abstract

Magnolia obovataThunb. is generally scattered through the forest in small patches, but occasionally forms large patches. The size and age distributions and spatial dispersions of M. obovataindividuals are investigated in the large patches belonging to different developmental stages. The results of field investigations suggest that: (1) most seedlings appear quickly and simultaneously from buried seeds under the original positions of the crown of fallen trees, and sprouts from stumps begin to grow when disturbances occur; (2) more than 60% of seedlings and sprouts die before the young stage; and (3) the individuals form a patch if such events repeat. A Monte Carlo simulation model is constructed for understanding the relationships between disturbance replication and the probability of large patch formation quantitatively. The model implies that more than four disturbance replications are necessary for forming large patches of canopy M. obovatatrees, and the sprouting ability from the stump has the role of maintaining the probability of patch formation when the conditions are unfavorable to its formation. The structures of patches of M. obovataare affected by the proportion of patch formation strategies, and the strategies are strongly related to disturbance regimes.     

Cellulolytic activity and virulence of Ophiostoma ulmi and O. novo‐ulmi isolates

The cellulolytic activity (exoglucanase, endoglucanase and β‐glucosidase) of Ophiostoma ulmi (four isolates), O. novo‐ulmi (19 isolates) and ‘fast‐waxy’ (five isolates) was determined in growth media containing carboxymethylcellulose (CMC) and cellulose powder. Differences in enzyme activities were observed among isolates, irrespective of the species and substrate used. Inoculation experiments on Ulmus minor with randomly selected isolates of O. ulmi (two isolates), O. novo‐ulmi (five isolates) and ‘fast‐waxy’ (two isolates) were also performed. Disease was assessed as the percentage of leaves showing yellowing and browning. Ophiostoma novo‐ulmi and ‘fast‐waxy’ isolates exhibited a great variability in their capacities to cause the disease. In the presence of CMC, a significant correlation between the activity of exoglucanase and β‐glucosidase in vitro and virulence was found.     

Tinctoporellus epimiltinus,a causal fungus of butt rot of Japanese cypress

One of the causal fungi of butt rot of Chamaecyparis obtusa in Kyushu Island, Japan, was identified as Tinctoporellus epimiltinus from cultural characters, and by mating and inoculation tests. The cultural characters of the isolates obtained from butt rot of C. obtusa and T. epimiltinus isolated from the basidiocarp tissue and from decayed wood were examined. The morphological characters and chemical reactions of the isolates from butt rot were typical for T. epimiltinus. Di‐mon mating tests were performed between five monospore isolates of T. epimiltinus and five heterokaryotic isolates from the butt rot. All of the monospore isolates examined were heterokaryotized by the isolates from butt rot. Tinctoporellus epimiltinus isolates were inoculated on roots of 24‐year‐old C. obtusa. Butt rot was observed on all inoculated trees 1–2 years after the inoculation, and the inoculated fungus was re‐isolated from the decayed parts of the inoculated trees.     

Molecular‐based identification and phylogeny of Armillaria species from Serbia and Montenegro

Armillaria causes problems of root rot, kill trees and decay wood in the forests of Serbia and Montenegro, but the species involved have not hitherto been identified. The aim of this study was to identify field isolates collected on 25 localities. Identification was based on restriction fragment length polymorphism (RFLP) analysis of intergenic spacer 1 (IGS1) region and comparisons of IGS1 sequence with those available on NCBI database. Phylogenetic analysis was performed on sequence information from selected isolates to determine possible interrelationships between isolates with different banding patterns and previously identified tester isolates of five European Armillaria species. Five Armillaria species were identified in 90 isolates obtained from forests in Serbia and Montenegro. Armillaria gallica was most frequently isolated, followed by A. cepistipes, A. mellea, A. ostoyae and A. tabescens; two isolates remained unidentified. Restriction digestion of IGS1 amplification products with AluI produced 10 RFLP patterns. Patterns G4 (400, 250, 180) for A. gallica and pattern X (400, 180, 140) for isolates 74 and 79 are reported for the first time in European isolates. Eight RFLP patterns were observed after restriction with TaqI. Two patterns each were observed for A. ostoyae and A. gallica, and one each for A. cepistipes, A. mellea, A. tabescens and isolates 74 and 79. Parsimony analyses based on the IGS1 region placed the isolates into four clades: one including A. mellea, the second containing A. gallica–A. cepistipes isolates, while isolates of A. ostoyae and A. borealis were in the third clade. Armillaria tabescens differed from all annulate species. Phylogenetic analysis supported the conclusion that European Armillaria species are closely related and separated from a common ancestor in the near past. According to this survey five European Armillaria species are present in the forests of Serbia and Montenegro, while A. borealis is not present in the studied ecosystems.     

Determination of vc and mating types of Cryphonectria parasitica isolates by multiplex PCR and their genetic diversity in 13 chestnut-growing provinces of Turkey

Vegetative compatibility (vc) and mating types and genetic diversity of Cryphonectria parasitica isolates were determined using 183 isolates obtained from 215 infected chestnut trees growing in 13 provinces of Turkey. Based on the cultural aspects, 143 of these isolates were evaluated as virulent whereas the remaining 40 isolates were hypovirulent. When vc types of 183 isolates were classically differentiated, 135 of them matched to EU-1 (82.3%), 29 of them to EU-12 (17.6%) vc type, whereas 19 of them did not match to the two. When molecular vic markers were used, all the isolates were assigned to two EU vc types; 149 to EU-1 (81.4%) and 34 (18.5%) to EU-12. Of the majority of the isolates, 134 (73.2%) had mating-type MAT-1, while 44 (24%) isolates had MAT-2 and 5 (2.8%) isolates had both mating types. The population analysis based on two DNA marker systems, Inter-Primer Binding Site and Start Codon Targeted Polymorphism, showed no intraspecific genetic variation among the C. parasitica isolates. The prevalence of two dominant vc types revealed by this study shows that biological control with hypovirulent EU-1 and EU-12 isolates will be significant for the country. The results might be helpful to chestnut breeders carrying out resistance breeding studies to manage this disease based on hypovirulence attributed to Cryphonectria hypovirus 1.     

In vitro interactions between bacteria isolated from Sitka spruce stumps and Heterobasidion annosum

Culture medium composition affected antagonism by bacterial isolates from Sitka spruce (Picea sitchensis) stumps against Heterobasidion annosum. Fifty percent of bacterial isolates inhibited H. annosum growth on sporulation agar or yeast–dextrose–peptone agar; only 10% of isolates caused inhibition on both media. Proportions of isolates inhibiting H. annosum varied with stump age; fewer isolates from 4‐ or 6‐year‐old stumps exhibited antagonism than isolates from older or younger stumps. Fifteen isolates showing antagonism on sporulation agar were tested against H. annosum in spruce wood cubes. None of the bacterial isolates alone caused a significant weight reduction in inoculated cubes. Relative inoculation times of bacterial isolates and H. annosum had an effect on weight loss in interactions; simultaneous inoculation with isolates and H. annosum inhibited weight loss caused by H. annosum compared with bacteria‐free controls. Inoculation with bacterial isolates 10 days before H. annosum had no effect on the decay rate. In contrast, inoculation with H. annosum 10 days before bacteria increased weight loss of cubes by 200% relative to cultures lacking bacteria. The effect of a mixed bacterial inoculum on weight change in 0.2‐mm spruce wood slips co‐inoculated with H. annosum, Resinicium bicolor, Hypholoma fasciculare, Stereum sanguinolentum or Melanotus proteus differed between different fungi.     

Comparison of Gremmeniella abietina isolates from Pinus sylvestris and Pinus contorta in terms of conidial morphology and host colonization

Gremmeniella abietina isolates from Pinus contorta in northern Sweden produced, in vitro, shorter conidia with fewer septa compared with isolates from Pinus sylvestris in the southern part of the country. After mycelial inoculation of shoots with G. abietina isolates from both host species, the resulting necroses were longer in P. sylvestris than in P. contorta. Keeping seedlings in artificial mild winter climate or detaching shoots from the seedling before inoculation caused longer necroses. No host specificity in colonization was found. Isolates from P. sylvestris caused longer necroses than did isolates from P. contorta, and both types of isolates caused longer necroses in P. sylvestris than in P. contorta. The differences found between the two G. abietina populations probably reflect regional variation in the fungus.     

Genetic characterization of Botrytis cinerea isolates collected from pine and eucalyptus nurseries in Bio‐Bio Region,Chile

A total of 55 Botrytis cinerea isolates collected from Pinus radiata and Eucalyptus globulus plants cultivated in nurseries located in the Bio‐Bio Region, Chile, as well as isolates collected from native plants such as Rubus spp and Aristotelia chilensis located near the nurseries were genetically characterized. All isolates carried the Bc‐hch2 allele, thus belonging to genetic Group II, which is now referred to as B. cinerea. Genotyping based on the presence of transposons Boty and Flipper showed differences between isolates related to the plant host. Thus, transposa isolates (containing both transposons) were detected in P. radiata and E. globulus, while vacuma isolates (containing neither transposon) were detected in all plants except E. globulus. Notably, boty isolates (containing just the Boty transposon) were detected at high frequencies in all plant hosts. Analyses to detect mutations involved in resistance to fungicides such as benzimidazoles (BZ), dicarboximides and QoIs also showed differences in the studied isolates. Isolates collected from E. globulus were shown to carry mutations for all tree fungicides, while those collected from P. radiata presented mutations involved in resistance to BZ only. Isolates collected from native plant hosts did not carry any of the mutations analysed.     

Development and verification of a diagnostic assay based on EF‐1 α for the identification of Armillaria species in Northern Europe

The overall aim of this study was to develop a new, reliable and rapid diagnostic assay for differentiating six European Armillaria species based on variation in their elongation factor‐1 alpha (EF‐1 α) gene sequences and to verify a set of species‐specific primers on 61 Armillaria isolates from Europe. Partial sequences of the EF‐1 α gene obtained in Armillaria borealis, Armillaria cepistipes, Armillaria gallica, Armillaria mellea, Armillaria ostoyae and Armillaria tabescens revealed sufficient interspecific variation to distinguish among species using nested primers. These primers gave unambiguous bands when tested on representative isolates of five of these species. However, the EF‐1 α sequences of European A. borealis isolates clustered into two distinct clades, termed here AbX and AbY. Specific primers were subsequently designed and tested successfully on both AbX‐type and AbY‐type A. borealis isolates. The taxonomy of A. borealis needs to be elucidated to determine whether a new, as yet unnamed Armillaria taxon exists in Europe. Three A. borealis isolates were also found to have heterozygous sites in their EF‐1 α sequences, which suggests that the gene could exist in more than one copy or that these isolates contain hybrid sequences. A pyrosequencing method was also developed, targeting a small region of EF‐1 α intron 4, which was able to differentiate European Armillaria isolates to the species level and additionally could distinguish AbX‐type and AbY‐type A. borealis isolates.