Molecular identification and relative abundance of cryptic Lophodermium species in natural populations of Scots pine,Pinus sylvestris L.

The multi-locus phylogenetic species recognition approach and population genetic analysis of Amplified Fragment Length Polymorphism (AFLP) markers were used to delineate Lophodermium taxa inhabiting needles of Scots pine (Pinus sylvestris) in native pinewoods within Scotland. These analyses revealed three major lineages corresponding to the morphological species Lophodermium seditiosum and Lophodermium conigenum, fruiting on broken branches, and Lophodermium pinastri, fruiting on naturally fallen needles. Within L. pinastri three well supported sister clades were found representing cryptic taxa designated L. pinastri I, L. pinastri II, and L. pinastri III. Significant differences in mean growth rate in culture were found among the cryptic taxa. Taxon-specific primers based on ITS sequences were designed and used to classify over 500 Lophodermium isolates, derived from fallen needles of P. sylvestris in three Scottish and one French pinewood site, into the three L. pinastri cryptic taxa. Highly significant differences in the relative abundance of the three taxa were found among the Scottish pinewood sites, and between the French and all of the Scottish sites.     

Relationship between foliar composition of red-pine and jack-pine seedlings and vulnerability to Lophodermium needle-cast disease

Summary The Mn and Al content of needles from two-year-old jack pine (Pinus banksiana) seedlings was found to be more than twice that of red pine (Pinus resinosa). It is speculated that the high Mn and Al content of jack pine seedlings may impart some degree of resistance to needle cast disease caused byLophodermium pinastri. Contribution from the Soils Dept., Univ. of Wis., Madison, in cooperation with and supported in part by the Wisconsin Dept. of Natural Resources. Publication approved by the Director of the Wisconsin Agricultural Experiment Station.     

Karyologische Untersuchungen an keimenden Ascosporen und Hyphenzellen von Lophodermium pinastri (Schrad.) Chev.

Zusammenfassung Die vorliegenden Untersuchungen sollen die karyologischen Verhältnisse in keimenden Ascosporen und Hyphenzellen von Lophodermium pinastri klären. Die Kernuntersuchungen erfolgten an fixiertem und gefärbtem Material (HCl-Giemsa).Bevor sich bei den Ascosporen Keimhyphen bilden, setzen Kernteilungen sowie die Bildung von Querwänden ein. 2 hauptsächliche Keimformen können unterschieden werden. L. pinastri ist ein Organismus mit mehrkernigen Hyphenzellen (im Mittel 3–6 Kerne/Zelle). Die Terminalzelle enthält im Mittel 7–30 Zellkerne. Zwischen den Kernzahlen der Terminal-und der ersten Folgezelle besteht eine schwache positive Korrelation.Die 4 untersuchten Stämme unterscheiden sich in ihren Kernzahlen hoch signifikant. Die mittlere Kernzahl je Hyphenzelle kann durch veränderte Umweltbedingungen (z. B. Nährboden) variieren.Die Ergebnisse stellen eine cytologische Bestätigung der zu beobachtenden morphologischen und physiologischen Variabilität von L. pinastri dar.

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Karyological studies of germinating ascospores and hyphal cells in Lophodermium pinastri (Schrad.) Chev.

Summary The studies clarify the karyological constitution in germinating ascopores and hyphal cells of Lophodermium pinastri. For the nuclear studies fixed and stained material (HCl-Giemsa) was used. Before the development of ascospore germ tubes, nuclear divisions occur and septa are formed. 2 main types of germinating ascospores could be distinguished. L. pinastri is an organism with multinucleate hyphal cells (average of 3–6 nuclei/cell). The hyphal tip cell contains an average number of 7–30 nuclei. There is a weak positive correlation between the number of nuclei in the tip cell and in the second cell following.The 4 strains studied differ highly significantly in their numbers of nuclei. The average number of nuclei/cell can be influenced by changed environmental conditions.The results confirm cytologically the morphological and physiological variability observed in L. pinastri.

     

Two new species of <Emphasis Type="Italic">Lirula</Emphasis> on <Emphasis Type="Italic">Abies</Emphasis> from Japan

Two new species of Lirula (L. japonica and L. exigua) on Abies mariesii collected in subalpine areas of northern Japan are described as members of Rhytismatales, Discomycetes. Lirula japonica causes needle cast in fir, but L. exigua seems to occur on the needles of physically damaged twigs. Morphological characteristics of both species are discussed.     

Fungi in Living Symptomless Needles of Pinus sylvestris with Respect to Some Observed Disease Processes

The mycoflora in living symptomless needles of Pinus sylvestris was investigated in three 5–8 year-old plantations in Southern Poland from 1987 to 1990. The needles from trees with symptoms of the autumn needle cast and from trees without such symptoms were treated separately. In total 960 of the current year and 720 of the previous year needles were collected. Fungi were isolated from 80.1 % of needles and 3671 cultures belonging to 86 fungal taxa were obtained. Seven species of fungi showed the rate of infection above 5%: Anthostomella formosa, Lophodermium seditiosum, Cydaneusma minus, Cenangium ferruginosum, Lophodermium pinastri, Sclerophoma pythiophila and Anthostomella pedemontana. The frequency of infection of needles by these species depended on needle age, season of the year, calendar year and site. The spread of fungi in needles was not too high. They were found in 35.8 % of needle sections (isolations were made from 10,080 sections). The needle base, middle and top were infected with more or less similar frequency, but the differences were considerable for the individual fungal species. Anthostomella formosa and A. pedemontana generally occurred slightly more frequently on needles of trees without symptoms of the autumn needle cast, while the other four common species ( Cenangium ferruginosum, Cyclaneusma minus, Lophodermium pinastri, Lophodermium seditiosum ) generally occurred more frequently on needles of trees showing such symptoms. There were considerable differences in this respect among plantations investigated.     

Development and seasonal variations of Lophodermium populations on Pinus thunbergii needle litter

A quantitative method was developed to describe Lophodermium (Rhytismataceae, Ascomycetes) populations on Pinus thunbergii needle litter, and seasonal patterns of population variation were examined based on this method. We focused on the formation of black zone lines across needles and the production of Lophodermium ascocarps on needle portions delimitated by zone lines. The study was carried out at a soil erosion control site on a mountain slope and at a coastal sand dune site. Most Lophodermium spp. on needle litter were identified as L. pinastri according to morphological characteristics of ascocarps and ascospores and DNA analysis. Zone lines were produced on needles when isolates of L. pinastri were in contact with other isolates of L. pinastri or with isolates of other species in dual culture tests. This observation provided a rationale to consider that individual colonies with ascocarps and delimitated by zone lines were occupied by a single Lophodermium isolate. Frequency of occurrence of Lophodermium colonies, total colony length, and mean colony number per needle were higher at the coastal sand dune site than at the soil erosion control site. Total colony length and mean colony number also varied with season. Mean colony length and mean ascocarp number per colony were not different between sites or seasons.     

Phylogenetics of Lophodermium from pine

Lophodermium comprises ascomycetous fungi that are both needle-cast pathogens and asymptomatic endophytes on a diversity of plant hosts. It is distinguished from other genera in the family Rhytismataceae by its filiform ascospores and ascocarps that open by a longitudinal slit. Nucleotide sequences of the internal transcribed spacer (ITS) region of nuclear ribosomal DNA were used to infer phylogenetic relationships within Lophodermium. Twenty-nine sequences from approximately 11 species of Lophodermium were analyzed together with eight sequences from isolates thought to represent six other genera of Rhytismataceae: Elytroderma, Lirula, Meloderma, Terriera, Tryblidiopsis and Colpoma. Two putative Meloderma desmazieresii isolates occurred within the Lophodermium clade but separate from one another, one grouped with L. indianum and the other with L. nitens. An isolate of Elytroderma deformans also occurred within the Lophodermium clade but on a solitary branch. The occurrence of these genera within the Lophodermium clade might be due to problems in generic concepts in Rhytismataceae, such as emphasis on spore morphology to delimit genera, to difficulty of isolating Rhytismataceae needle pathogens from material that also is colonized by Lophodermium or to a combination of both factors. We also evaluated the congruence of host distribution and several morphological characters on the ITS phylogeny. Lophodermium species from pine hosts formed a monophyletic sister group to Lophodermium species from more distant hosts from the southern hemisphere, but not to L. piceae from Picea. The ITS topology indicated that Lophodermium does not show strict cospeciation with pines at deeper branches, although several closely related isolates have closely related hosts. Pathogenic species occupy derived positions in the pine clade, suggesting that pathogenicity has evolved from endophytism. A new combination is proposed, Terriera minor (Tehon) P.R. Johnst.     

Species of Rhytismatales on Berberis from China

Three species of Rhytismatales on Berberis were found from Sichuan and Yunnan provinces in China. Two of them were described as new species to science, namely Hypoderma minteri and Lophodermium johnstonii. The third one was a known species, Hypoderma berberidis. The phylogenetic relationships of these species within the Rhytismatales were analyzed based on internal transcriber spacer ribosomal DNA. The results showed that the species of the Rhytismatales on Berberis, unlike most species on pines, were not closely related. Three ITS sequences from GenBank, named there as Lirula macrospora, were used in this study, but were found to be from misidentified sources. A key to species of Rhytismatales on Berberis worldwide is also given.     

<Emphasis Type="Italic">Lophodermium</Emphasis> on needles of conifers from Yunnan Province,China

Twelve Lophodermium species on needles of conifers are known in Yunnan, the eastern Himalayas in China. Recently, additional specimens were collected and identified. Two new species, Lophodermium dilutum on Pinus armandii and Lophodermium tsugae on Tsuga dumosa, were described and illustrated, and six species, L. autumnale, L. confluens, L. himalayense, L. kumaunicum, L. laricinum, and L. nitens, were recorded for the first time for Yunnan. A key to the Lophodermium species on needles of conifers for Yunnan is provided.     

Differential Gene Expression Reveals Candidate Genes for Drought Stress Response in Abies alba (Pinaceae)

Increasing drought periods as a result of global climate change pose a threat to many tree species by possibly outpacing their adaptive capabilities. Revealing the genetic basis of drought stress response is therefore implemental for future conservation strategies and risk assessment. Access to informative genomic regions is however challenging, especially for conifers, partially due to their large genomes, which puts constraints on the feasibility of whole genome scans. Candidate genes offer a valuable tool to reduce the complexity of the analysis and the amount of sequencing work and costs. For this study we combined an improved drought stress phenotyping of needles via a novel terahertz water monitoring technique with Massive Analysis of cDNA Ends to identify candidate genes for drought stress response in European silver fir (Abies alba Mill.). A pooled cDNA library was constructed from the cotyledons of six drought stressed and six well-watered silver fir seedlings, respectively. Differential expression analyses of these libraries revealed 296 candidate genes for drought stress response in silver fir (247 up- and 49 down-regulated) of which a subset was validated by RT-qPCR of the twelve individual cotyledons. A majority of these genes code for currently uncharacterized proteins and hint on new genomic resources to be explored in conifers. Furthermore, we could show that some traditional reference genes from model plant species (GAPDH and eIF4A2) are not suitable for differential analysis and we propose a new reference gene, TPC1, for drought stress expression profiling in needles of conifer seedlings.     

Revisiting tree-migration rates: Abies alba (Mill.), a case study

At northern temperate latitudes trees have adjusted their ranges substantially in response to changing climates during the Holocene. Results from dispersal model simulations suggest that postglacial migration rates may have been over-estimated from fossil pollen data. As a contribution to this debate, we infer the migration rates of Abies alba (Mill.), silver fir, as a case-study species, by using a spatially explicit approach based on fossil pollen but taking into account its modern genetic diversity pattern. Maximum estimates of migration rates from fossil pollen data alone are higher than 700 m yr^?1 during the Holocene. Considering the potential refugia as suggested from all the fossil data but restricting the area over which silver fir expanded from each glacial refugium using data on the current haplotype distribution, the estimated maximum migration rates of silver fir are less than 250 m yr^?1. Genetic information may allow for (1) the exclusion of those refugial areas where the species may have survived during the last glacial period but from which it did not spread or spread only very locally and (2) the delineation of the areas over which the species spread from each glacial refugium. The estimated rates in the present study are generally consistent with rates suggested from modelling approaches. This study shows that integrating fossil pollen records can improve simulations of dispersal processes and, thus, allow for better predictions of future changes in tree species’ ranges.     

Endophyte communities vary in the needles of Norway spruce clones

Endophytic fungi show no symptoms of their presence but can influence the performance and vitality of host trees. The potential use of endophytes to indicate vitality has been previously realized, but a standard protocol has yet to be developed due to an incomplete understanding of the factors that regulate endophyte communities. Using a culture-free molecular approach, we examined the extent to which host genotype influences the abundance, species richness, and community composition of endophytic fungi in Norway spruce needles. Briefly, total DNA was extracted from the surface-sterilized needles of 30 clones grown in a nursery field and the copy number of the fungal internal transcribed spacer (ITS) region of ribosomal DNA was estimated by quantitative PCR. Fungal species richness and community composition were determined by denaturing gradient gel electrophoresis and DNA sequencing. We found that community structure and ITS copy number varied among spruce clones, whereas species richness did not. Host traits interacting with endophyte communities included needle surface area and the location of cuttings in the experimental area. Although Lophodermium piceae is considered the dominant needle endophyte of Norway spruce, we detected this species in only 33 % of samples. The most frequently observed fungus (66 %) was the potentially pathogenic Phoma herbarum. Interestingly, ITS copy number of endophytic fungi correlated negatively with the richness of ectomycorrhizal fungi and thus potential interactions between fungal communities and their influence on the host tree are discussed. Our results suggest that in addition to environmental factors, endophyte communities of spruce needles are determined by host tree identity and needle surface area.     

The incidence of mistletoe (<Emphasis Type="Italic">Viscum album</Emphasis> ssp. <Emphasis Type="Italic">abietis</Emphasis>) on silver fir (<Emphasis Type="Italic">Abies alba</Emphasis>) in Croatia

The research on incidence of mistletoe (Viscum album ssp. abietis) on silver fir (Abies alba) was carried out in natural fir stands in Croatia. In the area of Gorski Kotar 32.8 % of the examined dominant fir trees were infected with mistletoe. The mistletoe incidence was presented according to the damage degrees of silver fir from 0 (healthy trees) to 4 (dead trees), rated by the crown defoliation and needle discoloration. With the increase of incidence, mistletoe spreads more onto more vital, i.e. less damaged trees. In the Dinaric Alps 28.6% of the examined fir trees were infected, this percentage amounting to 27.1% for the mountainous regions between the Sava and Drava rivers. The site and stand parameters (exposure, elevation, site quality, forest community and crown closure) were analysed in order to establish whether there was a correlation between these parameters and mistletoe incidence. There was a negative correlation between the elevation and mistletoe incidence. Among the compartments with a closed stands there were considerably less compartments with higher mistletoe incidence than among compartments with a sparsely closed and understocked stands. The other analysed site and stand parameters individually had no significant influence on mistletoe incidence. The correlation of silver fir mortality in 2004 and mistletoe incidence in 2002/03 was analysed, and their strong correlation was established. Mistletoe could be considered as a bioindicator of silver fir decline, and probably a significant contributor to that decline. In the areas where mistletoe incidence is great it can be presumed that silver fir is significantly damaged.     

连栽杉木林林下植被生物量动态格局

用空间一致时间连续的定位研究方法,在湖南会同杉木林生态系统国家野外科学观测研究站试验基地的第2集水区,对连栽杉木林林下植被生物量进行了12 a的监测,研究了林下植被种类的变化、生物量动态特征、生物量的组成与分布变化格局。结果表明:连栽杉木林在14a生长发育过程中,林下植物种类呈现波动性的减少趋势,其中木本植物物种数下降率为40.0%,草本植物物种数下降率为47.1%。林下植被生物量由杉木林3年生29.48 t/hm²下降至14年生的2.53 t/hm²,其中木本植物生物量由7.07 t/hm²,下降至1.25 t/hm²,下降了82.3%;草本植物由22.41 t/hm²,下降至1.28 t/hm²,下降了94.3%。在此期间,木本与草本植物生物量的高低均出现波动现象。3年生杉木林下木本植物以乔木树种生物量6068.97 kg/hm²最高,占总生物量85.88%,藤本植物生物量736.97 kg/hm²为次,占10.44%,灌木植物生物量259.87 kg/hm²最低,仅占3.68%。14年生杉木林下木本植物以灌木植物生物量881.87 kg/hm²为首,占总生物量70.73%,藤本植物生物量247.07 kg/hm²为次,占19.82%,乔木树种生物量117.87 kg/hm²最少,只占9.45%。3年生杉木林下草本植物以蕨类植物生物量8391.44 kg/hm²最高,占总生物量的37.44%,过路黄生物量36.77 kg/hm²最低,仅占0.16%。杉木14年生时,以芒生物量573.00 kg/hm²最大,占总生物量44.78%,金毛耳草生物量2.93 kg/hm²最小,仅占0.23%。研究结果,可为研究杉木林养分循环、碳平衡、维护和提高林地地力及可持续经营管理提供科学依据。     

Experimental cloud immersion and foliar water uptake in saplings of Abies fraseri and Picea rubens

Key message

Frequent cloud immersion events result in direct uptake of cloud water and improve plant water potentials during daylight hours in saplings of two dominant cloud forest species.

Abstract

In ecosystems with frequent cloud immersion, the influence on plant water balance can be important. While cloud immersion can reduce plant water loss via transpiration, recent advances in methodology have suggested that many species also absorb water directly into leaves (foliar water uptake). The current study examines foliar water uptake and its influence on daily plant water balance in tree species of the endangered spruce–fir forest of the southern Appalachian Mountains, USA. These mountain-top communities are considered relic, boreal forests that may have persisted because of the benefits of frequent cloud immersion. We examined changes in needle water content, xylem water potentials, and stable isotope values in saplings of the two dominant tree species, Abies fraseri and Picea rubens before and after a 24 h period of experimental cloud immersion. Both species exhibited foliar water uptake following immersion, evidenced by substantial changes in stable isotope values of extracted needle water that reflected the composition of the fog water. In addition, total needle water content improved 3.7–6.4 % following experimental submersion and xylem water potentials were significantly greater (up to 0.33 MPa) in cloud-immersed plants over control plants. These results indicate that foliar water uptake may be an adaptive strategy for utilizing cloud water and improving overall tree vigor in these most southerly distributed boreal species.     

Distribution and ecological traits of a rare and threatened fungus Hericium flagellum in Poland with the prediction of its potential occurrence in Europe

Hericium flagellum is a highly host-dependent wood-inhabiting fungus in Europe. Its occurrence is strongly connected to the distribution of silver fir (Abies alba). We analysed available data describing ecological factors, especially habitat, substrate preferences and phenology, which are regarded as drivers of H. flagellum occurrence. We also implemented ecological niche modelling to determine the potential range of the fungus. More than half of H. flagellum records (57%) were found in high conservation value areas, on fallen trunks of silver fir trees. The basidiomata were predominantly recorded between August and late November. Distribution of the tree host, precipitation in the driest month, isothermality and annual mean temperature were the most decisive factors influencing H. flagellum occurrence. We conclude that the disjunctive range at present, the risk of tree host extinction linked to habitat loss, and the limited dispersal of H. flagellum propagules are the main threats to this species.     

Effects of climate on diameter growth of co-occurring Fagus sylvatica and Abies alba along an altitudinal gradient

In high-elevation forests, growth is limited by low temperatures, while in Mediterranean climates drought and high temperatures are the main limiting factors. Consequently, the climate-growth relationships on Mont Ventoux, a mountain in the Mediterranean area, are influenced by both factors. Two co-occurring species were studied: silver fir (Abies alba Mill.) and common beech (Fagus sylvatica L.), whose geographical distribution depends on their low tolerance to summer drought at low altitude/latitude, and low temperatures (late frost and short length of the growing season) at high altitude/latitude. Firs and beeches distributed along an elevational gradient were investigated using dendroecological methods. Silver fir growth was found to be more sensitive to summer water stress than beech. On the other hand, beech growth was more impacted by extreme events such as the 2003 heat wave, and negatively related to earlier budburst, which suggests a higher sensitivity to late frost. These results are confirmed by the different altitudinal effects observed in both species. Beech growth decreases with altitude whereas an optimum of growth potential was observed at intermediate elevations for silver fir. Recent global warming has caused a significant upward shift of these optima. As found for the period 2000–2006, rising temperatures and decreasing rainfall may restrain growth of silver fir. If these trends continue in the future beech might be favored at low altitudes. The species will have a reduced capacity to migrate to higher altitudes due to its sensitivity to late frosts, although an upward shift of silver fir is likely.     

Sydowia polyspora associated with current season needle necrosis (CSNN) on true fir (Abies spp.)

Current season needle necrosis (CSNN) has been a serious foliage disorder on true fir Christmas trees and bough material in Europe and North America for more than 25 y. Approximately 2–4 weeks after bud break, needles develop chlorotic spots or bands that later turn necrotic. The symptoms have been observed on noble fir (Abies procera), Nordmann fir (A. nordmanniana) and grand fir (A. grandis) on both continents. CSNN was reported as a physiological disorder with unknown aetiology from USA, Denmark, and Ireland, but was associated with the fungus Kabatina abietis in Germany, Austria and Norway. In 2007, a fungus that morphologically resembled K. abietis was isolated from symptomatic needle samples from Nordmann fir from Austria, Denmark, Germany, Norway, and USA. Sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA of these cultures, plus a K. abietis reference culture from Germany (CBS 248.93), resulted in Hormonema dematioides, the imperfect stage of Sydowia polyspora, and thus the taxonomy is further discussed. Inoculation tests on Nordmann fir seedlings and transplants with isolates of S. polyspora from all five countries resulted in the development of CSNN symptoms. In 2009, S. polyspora was also isolated from symptomatic needles from Nordmann fir collected in Slovakia.     

Coexistence of Abies alba (Mill.) - Fagus sylvatica (L.) and climate change impact in the Iberian Peninsula: A climatic-niche perspective approach

Abies alba Mill. (European silver fir) and Fagus sylvatica L. (beech) are Eurosiberian species dispersed over the Iberian Peninsula. Climate change predictions indicate a rise in temperature and a decrease in precipitation in this region, threatening the future existence of these species. In the present study we analyzed the future topo-climatic suitability of Abies alba and Fagus sylvatica and the mixed forests of these two species, using the General Linear Models technique and data from the third National Forest Inventory (Ministerio de Agricultura PyA, 2007). We considered two modeling approaches based on niche theory: modeling community (Abieti-Fagetum) and overlapping individual species models. General trends showed an overall decrease in both species’ topo-climatic suitability and indicated that the Pyrenees will play a crucial role as a climatic refuge. The modeling approaches markedly differed, however, in their current and future spatial agreement. Despite good accuracy results, community modeling through co-occurrence does not encompass the environmental space of individual species prejudicing future assessments in new environmental situations, suggesting a need for future studies in community modeling.     

中国南部地区松树上的散斑壳菌Ⅰ.

近年作者对我国南部地区松树上的散斑壳属(Lophodermium Chev.)真菌进行了调查和研究。本文报道8个种,其中椭圆散斑壳(L.ellipticum Y.R.Lin)是新种,喜马拉雅散斑壳(L.himalayense P.F.Cannon & Minter)和库曼散斑壳(L.kumaunicum Minter &M.P.Sharma)为我国新记录种,南方散斑壳(L.australe Dearn.)等5种为国内已记载种。对新种作了拉丁文、汉文描述和图解,对新记录种进行了简要记述。另外,记载了已知种的寄主新记录和地理新分布。