Tubakia Dryina Research Articles

Fungi as potential factors limiting natural regeneration of pedunculate oak (Quercus robur) in mixed‐species forest stands in Poland

AbstractDieback of youngQuercus roburseedlings can limit natural regeneration in mixed‐species forest stands in Poland. The aim of this study was to examine the role of fungi in the dieback of oak seedlings in central Europe. Fungi were isolated from the stems and roots ofQ.robur, from both healthy seedlings and seedlings with symptoms, that were sampled from four stands in Poland. In total, 111 distinct taxa were identified. Ascomycota was dominant, representing 95.6% of the isolates. Among the taxa identified,Alternaria alternata,Colletotrichum fioriniae,Colletotrichumgodetiae,Coniella quercicola,Diaporthe eres,Gnomoniopsis paraclavulata,Ilyonectria rufa,Mucor genevensis,Penicillium glandicola,Tubakia dryina, andUmbelopsis changbaiensiswere most frequently isolated, and were consistently found in stems and roots of both healthy and diseased plants. The community compositions of fungi in healthy and diseased stems were similar, althoughFusariumspecies, especiallyFusariumsp. 1 (FTSC 5) andF.sporotrichioides, were found mainly in seedlings with symptoms. The pathogenicity of the most consistently isolated species from stems and roots of diseased seedlings was tested onQ.roburseedlings.F.sporotrichioidescaused the largest lesions on inoculated seedlings. Six weeks after inoculation,D.eres,C.fioriniae,G.paraclavulata,T.dryina, andF.sporotrichioideskilled 0%–18.8% of seedlings, whileI.rufaandIlyonectriapseudodestructansdid not cause any lesions or other symptoms. This study is the first comprehensive report suggesting that massive fungal attack can lead to oak seedling dieback in mixed‐species forest stands in central Europe.

Leaf spot disease on seedlings of Quercus acutissima caused by Tubakia dryina in Korea

Severe attack by a leaf spot disease was found on seedlings of Quercus acutissima in Jeungpyeong, Korea in 2017. Based on the morphological characteristics of the fungus, it was identified as a member of Tubakia. Sequence comparisons based on the ITS and 28S rDNA regions confirmed the identity of the fungus as Tubakia dryina. This is the first report of Tubakia leaf spot caused by T. dryina on Q. acutissima.

A re-evaluation of Tubakia, including three new species on Quercus and six new combinations.

Morphological comparisons and phylogenetic analyses of Tubakia species from leaves of Quercus spp. in Iowa and other areas of eastern USA revealed three novel species: Tubakia hallii, Tubakia macnabbii, and Tubakia tiffanyae. These species, as well as Tubakia dryina and Tubakia iowensis, are common leaf endophytes and pathogens on Quercus and Castanea in eastern USA, as is Tubakia americana comb. nov, originally described from Quercus in New Jersey as Actinopelte americana. New combinations of species on leaves of other hosts in the eastern USA include Tubakia gloeosporioides, Tubakia liquidambaris, and Tubakia nyssae. Asian species of Tubakia are phylogenetically compared, and the new combination Tubakia supraseptata is made to accommodate a Japanese endophyte known only by its sexual state. The earlier description of Dicarpella dryina as the sexual state of T. dryina is questioned. The new combination Tubakia stellata is made to accommodate an unusual species from Brazil.

The occurrence of Tubakia dryina in Poland – new hosts and ITS variation

SummaryThis study describes a preliminary investigation of the occurrence of Tubakia dryina in Poland, based on fungal isolations from symptomless leaves and from necrotic areas of leaf blades of Quercus robur, Fagus sylvatica and Tilia cordata. Occurrence of T. dryina on leaves of the two latter species is reported for the first time. Frequency of incidence on different hosts varied between tree species, with the highest rate on oaks and the lowest on linden. The results also suggest the ubiquitous occurrence of T. dryina on oaks in Poland. This situation is in contrast to previous observations showing much lower frequency of this fungus in the past. A preliminary, ITS‐based, analysis of genetic diversity among Polish isolates of T. dryina revealed the presence of two distinct haplotypes, both of which are widespread in Poland and occur on the same trees in most locations. No further genetic diversity was observed within either detected lineages using ITS analyses.

Tubakia dryina, symptoms and pathogenicity to Quercus robur

In 1999 disease symptoms on leaves of <em>Quercus robur</em> – necrosis, deformation and blackening of leaf petiole, followed by premature leaf fall were observed. <em>Tubakia dryina</em> was isolated from necrotic tissues and its pathogenicity to oak proved in infection experiments. The fungus caused necrosis of shoots and leaves. Dying leaves displayed also blackening of leaf petiole.

First Report of Tubakia dryina in Buds and Shoots of Quercus cerris and Quercus robur.

Tubakia dryina (Sacc.) Sutt. (teleomorph Dicarpella dryina Belisario & Barr) is a widespread leaf pathogen in northern temperate zones and is mainly associated with Quercus spp. During 2000, T. dryina was isolated from seasonal samplings of endophytic fungal communities of Turkey (Q. cerris L.) and English (Q. robur L.) oaks. Samples were taken from healthy and declining trees showing no symptoms of T. dryina in a coppice with saplings in Piedmont (northwestern Italy). Fragments of freshly opened buds (1-year-old shoots) and leaves were surface-sterilized by immersion in 75% ethanol for 1 min, in a NaClO solution (3 to 4% active ingredient) for 3 min, and in 75% ethanol for 30 s, then plated on potato dextrose agar. T. dryina was found in all sampled tissues. Its frequency in buds was higher in healthy trees than in declining trees (≈25 versus 12%; analysis of variance test P < 0.05), whereas no difference was found in shoots. T. dryina was also isolated from asymptomatic leaves, but more often from declining trees than from healthy ones (≈40 versus 10%; P < 0.05). No differences were observed when comparing the two oak species. The fungus was previously reported in buds of Q. nigra L. in North America (2), and it has also been isolated from symptomatic leaves of Q. cerris in a 5-year-old plantation (1). T. dryina was found in other studies in leaves and dead twigs of Q. robur. To our knowledge, this is the first report of T. dryina in buds and shoots of European oak species, suggesting an important role of this fungus as either an endophyte or a latent pathogen associated with oak decline.

Factors Affecting Infection of Water Oak,Quercus nigra,byTubakia dryina

Tubakia dryina is commonly associated with leaf spots of water oak growing in the Piedmont of Georgia. The fungus was isolated from leaves, buds, or twigs collected from symptomatic trees from October 1991 through August 1992. The greatest isolation frequency (82 to 92%) occurred on leaves sampled in June, July, and August; a lower frequency (29 to 62%) was obtained for spring and fall months. Conidial germination on 2% water agar occurred from 10 to 35°C with maximum germination between 20 and 30°C after 24 h. The disease severity ratings of inoculated excised leaves and leaves on trees in the field increased with time and developed at a somewhat faster rate later in the season. Leaves on 1-year-old water oak seedlings, growing in soil treated with diuron + imazapyr at less than recommended rates, developed more severe disease when inoculated with T. dryina than seedlings treated with each herbicide alone or no herbicide

Phytotoxins produced byTubakia dryina

Tubakia dryina, the causal agent of red oak (Quercus rubra) leaf spot, produced the phytotoxins isosclerone, 3-hydroxyisosclerone, 6-hydroxyisosclerone and 6-hydroxymellein in liquid culture. All toxins caused large necrosis when placed on leaves of red oak. Necrosis was also caused on white oak and eight different weed species. All toxins were non-specific phytotoxins.

Development of Tubakia dryina on host tissue

Excised leaves of Quercus rubra were inoculated with suspensions of conidia of Tubakia dryina and the development of the fungus on the leaf tissue was observed by scanning electron and light microscopy. Conidial germination was 2% after 6 h, 53% after 12 h, and 54% after 24 h. Germ tubes formed appressorium-like structures directly on the leaf cuticle or over stomata, or entered stomata directly. Development of conidiomata was first evident 24–72 h after inoculation. Conidiomata first appeared as a small mass of hyphal cells, which then proliferated in a radial fashion, with simultaneous formation of conidia. Conidiogenous cells later ceased to form conidia and became thick walled and pigmented, forming a dark scutellum. Conidiogenous cells continued to proliferate ventrally to the scutellum, producing a ring of conidia embedded in a sticky matrix, surrounding the conidioma. Leaf tissue colonized by the fungus became water soaked, and later turned brown and necrotic. Key words: Actinopelte, leaf spot, oak, pycnothyrium.

Pycnidial formation and pathogenicity in Tubakia dryina

Tubakia dryina produces pycnidial conidiomata on twigs of Quercus robur , whereas on the leaves rhizothyrial conidiomata are formed. Inoculation experiments did not result in the formation of necroses.

Nematodes of Norfolk Island.

plants. During transmission experiments it was possible to transmit A. ritzemabosi from tomato (After Baermann funnel extraction) to leaves of Chrysanthemum indicum L., L., Dahlia sp. cult. and Solanum nigrum L. where characteristic leaf lesions were produced. The unusual new recording on two out of six, young, 1-2 m high, Tristania trees which had been planted in a pasture, likewise prompted a search of the surrounding vegetation. Foliar lesions were found only on Lotos cornicuteius but not on several other weeds in the immediate vicinity of the infested Brisbane box trees and numerous nematodes were extracted. In this case it appears again possible that weeds were the source of infestation, because no symptoms had been observed before planting out, nor were plants from the same source, but planted out elsewhere, affected. Acknowledgements are due to staff members of the Centraalbureau voor Schimmelcultures, Baarn, The Netherlands, for identification of Botrytis nerctsstcote, Fusarium seccnert and Tubakia dryina; to my colleague H.M. Dance for identification of Phytophthora drechsleri and P. meadii; to G.H. Robertson for identification of Pythium otiqenarum and P. rostratum; to W. Thomas for confirming my identification of woody gall virus; and to J. Cole for confirming the indentity of Peniophora sacrata.

Conidium Ontogeny and Cytology of Tubakia dryina from Louisiana Hardwoods

SUMMARYThe nuclear condition of mycelium, fruiting body cells, conidiogenous cells and conidia was determined for Tubakia dryina. All cells in the fruiting body were uninucleate, but the conidia were binucleate. The type of conidium ontogeny was found to be proliferating phialidic.

Conidium Ontogeny and Cytology ofTubakia Dryinafrom Louisiana Hardwoods

The nuclear condition of mycelium, fruiting body cells, conidiogenous cells and conidia was determined for Tubakia dryina. All cells in the fruiting body were uninucleate, but the conidia were binu...