Characterization and population diversity of Erwinia amylovora strains originating from pome fruits in Serbia

The diversity of 30 Erwinia amylovora strains, isolated from quince, pear and apple trees on 14 localities in Serbia, was studied using bacteriological and molecular methods. In pathogenicity tests, all strains caused necrosis and oozing of bacterial exudate on inoculated immature pear, cherry and plum fruits, and induced hypersensitive reaction in tobacco leaves. The studied strains were Gram and oxidase negative, non-fluorescent, levan and catalase positive and facultatively anaerobic. The strains did not reduce nitrates, but utilized citrate and produced acid from sorbitol, hydrolyzed gelatine, produced reducing substances from sucrose and grew in the presence of 5% NaCl, but not at 36oC. Identity of the strains was confirmed by conventional and nested PCR methods. Rep-PCR with REP, ERIC and BOX primers resulted in amplification of several DNA fragments respectively, but showed no variation within the strains. However, different genetic profiles were obtained with RAPD-PCR by using six primers which enabled differentiation of the strains into four groups. Genetic differences between the studied strains did not correlate with the host plants, geographical origin or year of isolation.

Xanthomonas hyacinthi. [Descriptions of Fungi and Bacteria].

A description is provided for Xanthomonas hyacinthi. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Hyacinthus orientalis and Scilla tubergeniana (Liliaceae); by artificial inoculation: Galtonia candicans, Muscari armeniacum and Scilla hispanica (Liliaceae). DISEASE: Yellow disease of hyacinth. Initially, small dark green spots develop on leaves, which may coalesce and develop into streaks, mainly at the leaf margin. Streaks blacken to produce a distinctive 'black rim'. On bulbs, bacterial exudate can be seen between scales, which appear glassy and discoloured. Wet and windy weather, generally followed by dry, hot periods, increases the disease incidence. Similarly, frost, mist and hail can induces similar effects. Bacterial entry into healthy plants is generally through natural openings such as hydathodes and stomata or through wounds. Between 0.7-2.4% of hyacinth bulbs can be infected with yellow disease (VAN DOORN & ROEBROECK, 1993). The disease can be controlled by heat-treating the bulbs (VREERBURG et al., 1986) or the application of bactericidal foliar sprays (KOSTER et al., 1988). GEOGRAPHICAL DISTRIBUTION: ASIA: Japan. NORTH AMERICA: USA (Connecticut, Massachusetts, Michigan, Minnesota, New Jersey, Texas, Washington). AUSTRALASIA: Australia (New South Wales, Tasmania, Victoria). EUROPE: Austria, Denmark, Finland, Former Yugoslavia, Germany, Hungary, Ireland, Italy, Netherlands, Poland, Romania, Russian Federation, Sweden, United Kingdom. TRANSMISSION: By the movement of infected bulbs. Localised spread by the action of wind-blown water droplets, animal movements and the use of infected tools and bulb sorting equipment.

Xanthomonas populi. [Descriptions of Fungi and Bacteria].

A description is provided for Xanthomonas populi. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Populus balsamifera, P. deltoides, P. euamericana, P. tremula, P. tremuloides and P. trichocarpa × P. deltoides (Salicaceae). DISEASE: Bacterial canker of poplar. First visible on young branches which swell and crack producing a bacterial exudate. Large cankers may develop at these sites over several seasons, or other organisms may invade and cause rapid death of the distal part of the branch. The pathogen gains entry into the plant through wounds, e.g. leaf and stipule scars, insect punctures and frost cracks. GEOGRAPHICAL DISTRIBUTION: ASIA: China, Pakistan. EUROPE: Austria, Belgium, Czech Republic, Denmark, France, Germany, Hungary, Ireland, Luxembourg, Netherlands, Poland, Romania, Russian Federation, Slovakia, Sweden, Switzerland, United Kingdom, Yugoslavia. TRANSMISSION: The disease can be spread by the actions of wind and rain.

Acidovorax avenae subsp. cattleyae. [Descriptions of Fungi and Bacteria].

A description is provided for Acidovorax avenae subsp. cattleyae. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Cattleya spp., Phalaenopsis spp., and hybrids. The following have been reported: Catasetum Ecuador, Cattleya harrisoniana, C. warneri, C. Margaret Stewart × Schomburgkia thomsoniana, Cypripedium sp., Dendrobium sp., D. Joan Krishima, D. Sue Cornell, Doritaenopsis Clarelen, × Epidendrum obrienianum, E. pamplonense var. variegatum, Epiphronites veitchii, × Ionopsis utricularioides, Miltonia sp., Oncidium ampliatum, O. lanceanum, O. luridum, O. warscewiczii, Ornithocephalus bicornis, Phalaenopsis amabilis, Renanthera Brookie Chandler × Phalaenopsis Dos Pueblos, × Rodricidium Tahiti, Rodriguezia secunda, Rhynchostylis gigantea, R. gigantea alba, R. retusa, Sophronitis carnus, Trichocentrum tigrinum × Oncidium lanceanum, Vanda Alexander Bowman × Vanda Jennie Hashimoto, Vanda Bill Sutton, Vanda coerulescens, Vanda parishii × Phalaenopsis lueddemanniana and Vanilla sp. DISEASE: Leaf spots. The bacteria are thought to enter the plant through the stomata; lesions initially appear water-soaked and will blacken with age; a considerable amount of exudate may also be observed. Lesions can occur on any part of the leaf, older spots may be surrounded by a light green or yellow halo. The disease can kill seedlings and, with certain varieties, mature plants, should the infection reach the growing point. GEOGRAPHICAL DISTRIBUTION: Philippines, Taiwan, Italy, USA (Florida, CA), possibly Portugal (61, 284). TRANSMISSION: Bacterial exudate from heavily infected plants may act as source of inoculum.

Pseudomonas corrugata. [Descriptions of Fungi and Bacteria].

A description is provided for Pseudomonas corrugata. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Lycopersicon esculentum. Also isolated from symptomless roots of Medicago saliva. DISEASE: Tomato pith necrosis. The pith is discoloured brown to dark brown and may show cavities, especially in the lower parts of the stem. External symptoms frequently seen include chlorosis of upper leaves, sometimes a brown to black external stem lesion where the pith is most badly affected, bacterial exudate from leaf scars, pruning and other wounds, and on older plants prolific development of adventitious roots on the stems in areas where the pith is most badly affected. GEOGRAPHICAL DISTRIBUTION: South Africa, New Zealand (cultures at CMI), Denmark (62, 6), England, Germany (East 60, 5559; West 61, 6591), Italy (S. Sardinia 63, 1960), USA (CA 62, 2155; F 62, 3656; PA 59, 919 on Lucerne). The distribution is probably much more widespread than these records show. TRANSMISSION: The bacterium is probably common in the environment. It has, for example, been isolated from mains water which was being used to irrigate an affected crop. It is probably also spread from plant to plant by man in cultural operations. The disease is favoured by high humidity or wet foliage and high nitrogen levels in the soil; conditions that favour soft plant growth that is most susceptible.

Pseudomonas syringae pv. sesami. [Descriptions of Fungi and Bacteria].

A description is provided for Pseudomonas syringae pv. sesami. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Sesamum indicum. Inoculation of Phaseolus vulgaris stems and pods produces characteristic reddish spots with bacterial exudate, but leaves are not infected. Limited reactions reported for some other plants by Sutic & Dowson (1962) were probably what would now be called hypersensitive reactions. DISEASE: Dark brown to black leaf spots tending to be limited by veins. Spots may also appear on all other above-ground parts. On stems they often elongate and coalesce into lesions several cm long. Early infection of capsules may turn them black. Seriously infected plants may die. Under damp conditions epidemics cause severe losses. GEOGRAPHICAL DISTRIBUTION: Tanzania, China, India, Japan, Korea, Turkey, Bulgaria, Greece, Yugoslavia, USA, Brazil (see CMI Map 398, ed. 2, 1973). Recent reports not included on the map are Uganda (56, 116), South Africa (58, 1681), Mexico (55, 5647) and Venezuela (54, 524). The known distribution in India now includes the whole of UP (49, 2389a). TRANSMISSION: Within the crop transmission is presumed to be by wind-driven rain. Seed transmission occurs (58, 5764) and allows spread into new areas.

Corynebacterium tritici. [Descriptions of Fungi and Bacteria].

A description is provided for Corynebacterium tritici. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Triticum aestivum. Sabet (1954a) obtained infection artificially on T. dicoccum, T. durum and T. pyramidale, using the nematode vector. Williams (1964) claimed infection of Dactylis glomerata and Secale cereale, but no details of the inoculation method used have been published. DISEASE: Yellow slime or 'tundu' disease of wheat. Infected parts bear yellow slimy bacterial exudate. Wheat ears covered by such slime become distorted or fail to emerge properly and produce little or no grain. On leaves and sheaths long slimy yellow spots may be seen. The bacterium has an obligate association with the ear-cockle nematode, Anguina tritici. GEOGRAPHICAL DISTRIBUTION: India and Egypt (CMI Map 156a, ed. 1, 1966), to which should be added W. Australia (6, 216), China (Hopei & Kweichow) (26, 446), Cyprus (17, 15), Ethiopia (48, 3413a) and Iran (49, 445). TRANSMISSION: The bacterium is carried with the seed in infected galls of the ear-cockle nematode Anguina tritici. The presence of the nematode is considered essential for the establishment of the bacteria in the plant, and many different attempts to inoculate wheat artificially in the absence of the nematode have failed to produce infection (e.g. Hutchinson, 1917; 4, 470; 6, 216; 26, 446; 51, 2391). Chaudhury (14, 571) claimed successful inoculation of the bacteria alone, but later workers have refuted this. Severin & Docea (50, 1047y) and Williams (1917) reported successful artificial inoculations, but little or no details of the methods are given. Neither report mentions use of nematodes. The bacteria carried by galls can remain viable for at least 5 years (45, 3125), while the nematodes within the galls are known to remain viable for even longer periods. Experiments of Swarup & Singh (43, 1299) indicate that the bacteria are not carried within the galls on or inside the larvae, but probably on the gall surface.

Xanthomonas oryzicola. [Descriptions of Fungi and Bacteria].

A description is provided for Xanthomonas oryzicola. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Oryza saliva. Some weed species of Oryza have also been reported to be susceptible (45, i789). Weakly pathogenic to Leersia hexandra by artificial inoculation. DISEASE: Bacterial leaf streak of rice. Narrow, dark greenish, water-soaked streaks of various lengths appear between the veins. Minute amber droplets of bacterial exudate are commonly found on these lesions. Later the lesions extend and coalesce giving large brownish patches. In the late stages symptoms are difficult to distinguish from bacterial leaf blight. GEOGRAPHICAL DISTRIBUTION: Confined to tropical Asia. Reported from China, India, Philippines, Thailand and West Malaysia (CMI Map 463 and 49, 144).TRANSMISSION: The pathogen spreads within a crop in surface moisture and may enter the leaf through minor abrasions or stomata. Warm wet weather is favourable to both spread and development of the tisease. Introduction into new areas can occur in seed from infected plants (48, 1693).

Pseudomonas striafaciens. [Descriptions of Fungi and Bacteria].

A description is provided for Pseudomonas striafaciens. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Avena sativa, A. byzantina and Hordeum vulgare are also susceptible (Elliott, 1951). Tessi (1953) showed that Briza maxima, Bromus catharticus, B. hordeaceans and B. rubens are all slightly susceptible to artificial inoculation. DISEASE: Bacterial stripe blight of oats. Lesions appear mainly on the leaves as sunken, water-soaked spots, which grow or coalesce forming long water-soaked stripes. Bacterial exudate is often seen, especially under humid conditions. Older lesions become a translucent brownish colour. Sheaths, culms, pedicels and glumes are sometimes affected. GEOGRAPHICAL DISTRIBUTION: N. America, Argentine, U.S.S.R. Australia (CMI Map 363, 1959) and Japan (47, 2693). TRANSMISSION: As for P. coronafaciens.