The fatty acid composition and its alterations due to different incubation temperature in the lipids of aggressive and non-aggressive strains of Ceratocystis ulmi

Lipids and their fatty acids from the mycelia of aggressive and non-aggressive strains of Ceratocystis ulmi were examined at different incubation temperature. The quantity and degree of fatty acid unsaturation were correlated with the pathogenicity of the fungus.     

Compatibility in Ceratocystis ulmi

Fourteen strains of Ceratocystis ulmi were crossed on semi-synthetic and synthetic media in vitro. Perithecia formed after 8 weeks of incubation. Some strains were found to be more fertile than others. The strains were classified into type A, type B and bisexual.     

Ultrastructure of Ceratocystis ulmi

Transmission electron microscopic observations of C. ulmi show that there are three distinct types of the hyphae and three distinct layers forming the nscocarp peridium. The cellular organelles of the hyphae and ascocarp peridial layers are described.     

Further studies on the activity of cell wall degrading enzymes of aggressive and non-aggressive isolates of Ophiostoma ulmi

In vitro activity of glycosidases and exo-glycanases in 10 aggressive and 10 non-aggressive isolates of Ophiostoma ulmi were compared. Enzyme preparations of aggressive isolates released more arabinose and xylose from cell walls of elm wood than those of non-aggressive isolates. Significantly more rhamnose was released as well by enzyme preparations of aggressive isolates, although some of non-aggressive isolates released comparable amounts.     

Further studies on pathogenicity in Ceratocystis ulmi1

Inoculation experiments on Ulmus procera, U. glabra and U. pumila with isolates of Ceratocystis ulmi from Canada, the United States, England, France, the Netherlands and Iran confirmed earlier work on the correlation between cultural characters and pathogenicity. Inocula-     

A scanning electron microscope study of cell wall degradation in elm wood by aggressive and non-aggressive isolates of Ophiostoma ulmi

Degradation of cell walls in elm wood tissue (Ulmus americand) by aggressive and non-aggressive isolates of Ophiostoma ulmi was studied by scanning electron microscopy. Xylem vessel walls were much more affected after infection with the aggressive isolate than after infection with the non-aggressive one.     

Terpenes and unsaturated fatty acids trigger coremia formation by Ceratocystis ulmi

Coremia formation by Ceratocystis ulmi (Buis.) ist triggered by certain terpenes and unsaturated fatty acids, of which linoleic acid and its esters are the most active.     

Fatty acids triggering coremia formation by Ceratocystis ulmi their occurrence and distribution in elm wood

This paper reports the identification of fatty acids in elm wood and its active extractives triggering coremia formation, their distribution between bark, sapwood and heartwood of elms, and their occurrence in the mycelium of the pathogen.     

Presence and accumulation of fungitoxic substances against Ceratocystis ulmi in Ulmus americana: possible relation to induced resistance1

This paper reports the differential accumulation of inhibitory compounds in American elm seedlings after inoculation with a non-aggressive and an aggressive strain of C, ulmi.     

Inhibition of Ceratocystis ulmi by mansonones A,C, D,E, F,and G isolated from Ulmus americana

Six mansonoes, previously isolated from Ulmus americana L. infected by Ceratocystis ulmi (Buis.) C. Moreau, were assayed for their inhibitory activity against several strains of the fungus. Mansonone A was most effective in inhibiting the linear growth of six strains of C. ulmi tested. A mixture of the pure mansonones, recombined at their original concentrations, was less inhibitory to the three aggressive strains of C. ulmi than the non-aggressive ones. The total mansonone fraction accounted for all the inhibition of the three non-aggressive strains.     

Electrophoretic protein profiles of strains of Ceratocystis fimbriata f. sp. platani

Soluble proteins extracted from the mycelium of strains of Ceratocystis fimbriata (Ell. et Halst) Davidson f. sp. platani Walter were separated on native and SDS-polyacrylamide gradient gel electrophoresis. The protein patterns were compared and the electrophoretic profiles of all the strains examined showed striking intraspecific similarities. The use or protein banding patterns as a diagnostic criterion to distinguish strains of C. fimbriata is discussed.     

The survival of Ceratocystis fagacearum in South Carolina

This research, which involved observing and sampling artificially inoculated oak-wilted turkey oak trees, substantiates previous field observations that C. fagacearum does not quickly kill oak trees in South Carolina. C. fagacearum seems to quickly lose virulence during the first growing season following inoculation. Rather than being quickly killed, as occurs with infected red oaks in more temperate climates, oak trees in South Carolina either survive infection or die much more slowly. Moisture, total carbohydrate, and reducing sugar contents of infected trees indicate that these trees suffer an initial physiologic trauma. Branches die first, followed by upper stems, and in few cases lower stems. Some trees, however, have survived inoculation, and initial partial wilting, but have since recovered.     

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.     

Identification and characterization of bacterial strains associated with diseased oak trees in Northern Iran

Oak decline syndrome is characterized by periodic occurrences of decline and death of oaks over widespread areas. An outbreak of a new emerging disease on oak trees was reported in the Hyrcanian forest of Iran (Mazandaran and Golestan provinces) that showed stem bleeding and canker symptoms. Bacterial isolates were characterized through biochemical and physiological tests, protein electrophoresis, DNA fingerprinting (rep‐PCR, ERIC and BOX primers) and sequencing of 16S rRNA and MLSA (multilocus sequencing analysis) for housekeeping genes (gyrB, infB and atpD). A complex community of the genus Brenneria spp. (Brenneria goodwinii, Brenneria roseae subsp. roseae, Brenneria sp. and Brenneria nigrifluens) and a few isolates in the genus Gibbsiella were identified as major groups involved. Isolate differentiation was more accurate using concatenated partial gene sequences within the main groups. All bacterial isolates showed hypersensitivity reactions (HR) on Pelargonium leaves (Pelargonium × hortorum). Pathogenicity studies of different Brenneria and Gibbsiella strains revealed that they have potential to cause the disease in oak seedlings and devastating oak canker and stem bleeding symptoms in northern Iran. Due to the presence of several potentially pathogenic agent(s) associated with the oak decline, identification of the principal agent(s) is of major interest. To our knowledge, this is the first report of potentially pathogenic bacteria associated with oak bleeding and canker in Iran.     

First report of Ceratocystis platani in Albania

The fungus Ceratocystis platani was detected in various localities of the Gjirokastër prefecture in southern Albania, where it was causing widespread mortality on Platanus orientalis trees. The identification of the fungus was based on both morphological characteristics in culture and DNA sequencing. The pathogenicity of C. platani was confirmed in inoculations on seedlings of P. orientalis. To our knowledge, this is the first report of C. platani in Albania.     

我国橡胶木长喙壳属分离物的研究

研究了橡胶木上长喙壳属66个分离物的形态特征。通过形态比较和鉴定,证实橡胶木上的长喙壳属菌分离物分属于甘薯长喙壳(Ceratocystis fim briata)和橡胶长喙壳(C.heveae)两种真菌,二者都能引起橡胶木变色。     

Ceratocystis smalleyi colonization of bitternut hickory and host responses in the xylem

Colonization of Carya cordiformis sapwood by Ceratocystis smalleyi and subsequent host defence responses following artificial inoculation were investigated using anatomical and histological techniques. Hyphae of C. smalleyi were observed in all sapwood xylem features confirming the ability of the pathogen to invade and colonize the xylem tissues of the host species. The fungus was isolated from within and at the margins of discoloured sapwood areas at 2 and 12 months after inoculation. General host defence responses that included vessel occlusion with gels or tyloses, lipid accumulation, and production of phenolic compounds were observed in xylem tissues of inoculated C. cordiformis stems. Pectic substances, lipids, and to a rare extent, phenolic compounds were detected in vascular gels. The lipid‐rich barriers observed likely prevent lateral expansion of the fungus in the sapwood. Furthermore, lack of fungus sporulation within vessels may restrict axial spread of the fungus. C. smalleyi appears to be a limited vascular wilt pathogen of bitternut hickory based on these observations and previously reported sap flow reduction correlated with multiple infections in artificially inoculated trees.     

桉树和相思树Ceratocystis枝干枯萎病研究进展

Ceratocystis致病菌可感染树木枝干和根部的伤口部位,导致被感染部位枯萎,严重情况下可导致枝干或整株树木死亡。桉树和相思树是世界热带、亚热带地区的重要商品林树种,Ceratocystis枝干枯萎病给桉树和相思树的健康发展带来了一定的威胁,特别是在东南亚和非洲地区。最近,本文作者从广东湛江地区的桉树商品林里面分离并鉴定到两个Ceratocystis种,Cacaciivora和一个新描述的种Cchineucensis,致病力测试显示Cacaciivora对测试的桉树无性系具有较强的致病力,桉树不同无性系对Cacaciivora的抗性存在显著的差异。本文介绍了Ceratocystis的生物学特性、分类依据和方法,在世界范围内的分布和危害以及防控措施,以应对Ceratocystis病原对我国华南桉树和相思树商品林的危害。     

Factor in Abies balsamea Responsible for Coremia Formation of Ceratocystis piceae

Compounds are present in sapwood of Abies balsamea (L.) Mill., triggering the formation of coremia by Ceratocystis piceae (Münch) Bakshi. From several unsaturated fatty acids, linoleic acid is the most active coremia inducer.     

Ceratocystis fimbriata of plane trees in Italy: biological aspects and control possibility

The biology of the pathogenic agent of plane tree canker (Ceratocystis fimbriata f.platani), the vectors of the disease and the results of some preventive and curative treatments are described in detail.