Pestalotiopsis Species Research Articles

First Report of Pestalotiopsis maculans Causing Necrotic Leaf Spots in Nursery Plants of Arbutus unedo and Ceratonia siliqua in Spain

Forestation of agricultural lands has led to a great increase in the production of plants in forest nurseries in southern Spain. During a disease survey of several nurseries, performed in 1998 and 1999, a necrotic leaf spot was found causing defoliation in seedlings of two mediterranean forest species, the ericaceous shrub Arbutus unedo and the leguminous tree Ceratonia siliqua. The affected plants were 9 to 24 months old and growing in fertilized peat in containers. Symptoms on both species consisted of large necrotic lesions (up to 20 mm in diameter) that were located mainly, but not exclusively, along the leaf margin. On A. unedo, necrotic spots were bordered by a red halo, while on C. siliqua the halo was dark. The fungus consistently isolated from both hosts was identified as Pestalotiopsis maculans (Corda) Nag Raj (=Pestalotiopsis guepinii), based on morphological characters (1). Acervular conidiomata (up to 200 μm in diameter) developed on the necrotic lesions of leaves incubated at 100% relative humidity and 20 to 24°C, and in cultures on potato dextrose agar (PDA) at 20 to 24°C over the course of 7 days. All isolates had 5-celled smooth conidia. Apical and basal cells were hyaline, while the three median cells were brown; the upper two were darker than the lower one. Conidia were 22 to 30 μm (mean length) and 5 to 9 μm (mean width). There were typically three (range 1 to 4) apical appendages averaging 17 μm long. The average basal appendage was 6 μm long. One-year-old seedlings and detached leaves from healthy field trees of A. unedo and C. siliqua were sprayed to runoff with an aqueous conidial suspension (106 conidia ml-1) of two isolates of the fungus. All inoculated and control plants sprayed with water only were incubated in a growth chamber at 100% relative humidity and 20 to 24°C for 48 h and then in the same growth chamber at 50 to 80% relative humidity or in the greenhouse (10 to 30°C and 40 to 80% relative humidity) until symptoms developed. Detached leaves were incubated to prevent desiccation in a humid chamber at 100% relative humidity and 20 to 24°C for 2 months. After a period of 2 to 4 months, lesions developed on all inoculated leaves but not on noninoculated controls. Lesion morphology on both hosts was similar to that observed in naturally infected plants in the nurseries. P. maculans was reisolated from lesions of all infected leaves but not from control leaves. Although other species of Pestalotiopsis have been reported infecting leaves of C. siliqua (1), to our knowledge, this is the first report of a Pestalotiopsis sp. on A. unedo and of P. maculans on C. siliqua. Reference: (1) T. R. Nag Raj. Coelomycetous Anamorphs with Appendage-Bearing Conidia. Mycologue Publications, Waterloo, Ontario, Canada, 1993.

Phylogenetic significance of morphological characters in the taxonomy of Pestalotiopsis species

There has been considerable disagreement regarding the relationships among Pestalotiopsis species and their delimitations. A molecular phylogenetic analysis was conducted on 32 species of Pestalotiopsis in order to evaluate the utility of morphological characters currently used in their taxonomy. Phylogenetic relationships were inferred from nucleotide sequences in the ITS regions and 5.8S gene of the rDNA under four optimality criteria: maximum parsimony, weighted parsimony, maximum likelihood, and neighbor joining. Phylogenies estimated from all analyses yielded trees of essentially similar topology and revealed 3 major groups that correspond with morphology-based classification systems. Molecular data indicated that the genus contains two distinct lineages based on pigmentation of median cells and four distinct groupings based on morphology of apical appendages. The analyses did not support reliability of other phenotypic characters of this genus, such as spore dimensions. Characters with particular phylogenetic significance are discussed in relation to the taxonomy of Pestalotiopsis.

Biodiversity of endophytic fungi Pestalotiopsis

Pestalotiopsis species is an important group of endophytic fungi. Endophytic Pestalotiopsis distributed in roots, stems, leaves and reproductive parts of its host plants. Twenty-three endophytic Pestalotiopsis species have been identified. The colonization rates of endophytic Pestalotiopsis in observed plants were greatly different. Endophytic Pestalotiopsis was a dominant group in the tissues of Rhizophora apiculata, Cocos nucifer, Taxus yunnanensis, Camellia sasanqua, Fragraea bodenii and Cordemoya integrifolia. Most of endophytic Pestalotiopsis colonized more than one host plant, however, a few of them colonized only one. The distributions of endophytic Pestalotiopsis are related to ecological and environmental conditions and location of host plants. Some endophytic Pestalotiopsis act either as parasites or as saprophytes due to the different stage of host plants and (or) environmental conditions. Endophytic Pestalotiopsis produced a variety of secondary metabolites including antitumor components (taxol and torreyanic acid), antifungal and antibacterial components (cyclohexenone, torreyanic acid and pestaloside) showing a bright future of application.

Diversity and host preference of leaf endophytic fungi in the Iwokrama Forest Reserve, Guyana

Endophytic fungi were isolated from living symptomless leaves of 12 tree species from two locations in the Iwokrama Forest Reserve, Guyana. Sixty-four fungal morphotaxa were characterized from 2492 cultures, which were derived from a total of 2520 sample units. Species of Colletotrichum, Nodulisporium, Pestalotiopsis and Phomopsis were most frequently isolated. Colonization was greater in samples from the midrib than in those from laminar tissue, and slightly greater at the tip of the lamina compared with the base of the leaf. In contrast to studies in temperate ecosystems, no distinct fungal communities were identified for individual plant species, suggesting that the degree of host preference is low. The implications for estimation of fungal diversity in tropical systems are explored.

Diversity and Host Preference of Leaf Endophytic Fungi in the Iwokrama Forest Reserve, Guyana

Endophytic fungi were isolated from living symptomless leaves of 12 tree species from two locations in the Iwokrama Forest Reserve, Guyana. Sixty-four fungal morphotaxa were characterized from 2492 cultures, which were derived from a total of 2520 sample units. Species of Colletotrichum, Nodulisporium, Pestalotiopsis and Phomopsis were most frequently isolated. Colonization was greater in samples from the midrib than in those from laminar tissue, and slightly greater at the tip of the lamina compared with the base of the leaf. In contrast to studies in temperate ecosystems, no distinct fungal communities were identified for individual plant species, suggesting that the degree of host preference is low. The implications for estimation of fungal diversity in tropical systems are explored.

Eight species of Pestalotiopsis collected from various broadleaved trees in Shimane Prefecture, Japan.

Eight species of Pestalotiopsis collected from various broadleaved trees in Shimane Prefecture, Japan.

Evaluation of artificial neural networks for fungal identification, employing morphometric data from spores of Pestalotiopsis species

The relative abilities of the multilayer perceptron, radial basis function, asymmetric radial basis function and learning vector quantization artificial neural networks (ANNs) and two non-neural methods to identify fungal spores were compared. ANNs were trained on morphometric data from spores of Pestalotiopsis spp. and a few species in the related Truncatella and Monochaetia. The optimized neural and statistical classifiers had similar identification success on an unseen data set – between 76-0 and 78-8% of a 16-species group and between 63-0 and 67-7% of a 19-species group. The relative merits of each classifier are discussed, as is the potential of ANNs in mycology.

Polysaccharides in Fungi. XXXVIII. Anti-diabetic Activity and Structural Feature of a Galactomannan Elaborated by Pestalotiopsis Species.

A fungus of Pestalotiopsis species produced an extracellular, water-soluble polysaccharide (PS-N). PS-N exhibited significant hypoglycemic activity in streptozotocin-induced diabetic mice following intraperitoneal administration and had an effect on oral glucose tolerance in normal mice following oral administration. PS-N ([alpha]D +34.5 degrees in water) was homogeneous on gel chromatography, it is composed of galactose and mannose in a molar ratio of 1:9, and its molecular weight was estimated by gel chromatography to be about 24,000. Its structure was investigated by a combination of chemical and spectroscopic methods. The results indicated that PS-N, a highly branched galactomannan, is composed of beta-(1-->3)-linked D-galactofuranosyl and non-reducing terminal beta-D-galactofuranosyl residues, in addition to alpha-D-mannopyranosyl residues of a yeast mannan type.

The ecology of fungal cankers on Cupressus macrocarpa in southern England

SummaryBark isolations from cankers on Cupressus macrocarpa in southern England yielded Seiridium cardinale, Pestalotiopsis funerea and Pestalotiopsis monochaetioides. The recovery pattern of the three fungi indicated that only S. cardinale was a primary pathogen; the two Pestalotiopsis species being secondary. Pathogenicity data obtained following the inoculation of C. macrocarpa branches with mycelium of the three fungi confirmed this view.No evidence of vegetative incompatibility was found in S. cardinale, but five vegetative‐compatibility (vc) groups were found in P. funerea and six in P. monochaetioides. Different vc groups of the two Pestalatiopsis species were often found in the same S. cardinale lesion, suggesting that a number of separate colonization events were involved. It is possible that this sometimes leads to complete replacement of the pathogen.

Cyclopaldic acid, a major phytotoxic metabolite of Seiridium cupressi, the pathogen of a canker disease of cypress

A phytotoxic substance was produced in vitro in a relatively high concentration (c. 40 mg/1) by Seiridium cupressi, a fungus that causes a canker disease of cypress (Cupressus sempervirens) and other Cupressaceae in Greece and in other parts of the world. Structural investigations demonstrated that the substance was identical with cyclopaldic acid, an antibiotic known to be a metabolite of some species of Penicillium, Aspergillus and Pestalotiopsis. Absorbed by severed twigs of three species of Cupressus and by cuttings of two herbaceous non‐host plants (tomato and mung bean), cyclopaldic acid at concentrations of 10‐100 ug/ml induced leaf chlorosis and necrosis. Oat seed germination and root growth of oat seedlings were also reduced to about 50% at 75 and 100 jig/ml, respectively. The compound showed antifungal activity towards species of Botrytis. Fusarium and Geotrichum when assayed at a concentration range from 10 to 100 /ug ml. We believe this to be the first report of cyclopaldic acid as a non‐selective fungal phytotoxin. However, its possible role in the pathogenesis of the cypress canker disease has not been established.

Conidial structure in two species of pestalotiopsis

Sections of developing and mature conidia of Pestalotiopsis funerea Desm. and P. triseta (F. & J. Moreau) Steyaert were examined ultrastructurally. Conidia are sheathed in single-layered walls in which the peripheral zone becomes electron dense. In P. triseta the septum separating the upper two median cells, together with the lateral conidial walls, are impregnated with melanizing material. Evidence is presented which indicates similarities between melanin deposition in fungi and lignification in the cells of higher plants.

Genera coelomycetarum. II. Doliomyces

The type species of Doliomyces, D. senegalensis, is redescribed. Doliomyces mysorensis sp. nov. is described from decaying leaves of Artocarpus integrifolia. Conidium ontogeny in this species is identical with that of some species of Pestalotia and Pestalotiopsis.

Some Hitherto Unrecorded Species of Pestalotia and Pestalotiopsis from India

Some Hitherto Unrecorded Species of Pestalotia and Pestalotiopsis from India

New and old species of Pestalotiopsis

In continuation of a monographic study of the genus (Steyaert, Bull. Jard. bot. Brux. 19 , 285–354, 1949) further species are described and illustrated on a uniform scale: Pestalotiopsis nattrassii n.sp., P. adusta (Ell. & Ev.) nov.comb., P. neglecta (Thuem.) nov.comb., P. gigas n.sp., P. owenii n.sp., and P. owenii var. major n.var. Collections of P. mangiferae, P. disseminata, P. royenae, P. theae var. major, P. papposa, P. virgatula, P. versicolor, P. glandicola , and P. funerioides from various sources are described and annotated.