The influence of different host plants on phenotype and pathogenicity of C.m. subsp. michigansis was studied. The bacterium responds by changing or preserving its phenotype when pass through different host plants. The bacterium doesn't change when pass through host plants from Graminae and Cucurbitacae families. The isolates from S. microcarpon and radish are differed in the biochemical properties in comparison with the remaining isolates.
The data on the pathogenicity of isolates from different host plants of C.m. subsp. michiganensis are indicated on table 1. The highest pathogenicity is shown when the bacterium pass thorough host plants from Graminae and Cucurbitacae families. The lowest pathogenicity is established with eggplant, tobacco, beans and onion isolates. Isolates form Datura Stromonium and radish didn't inoculate tomato plants. These were the isolates that differ mostly by their biochemical properties. It is evident that bacterium didn't lose its pathogenicity passing through the host plants from Graminae and Cucurbitacae families and has lost it pathogenicity absolutely passing through D. Stromonium and radish plants.
Our data indicated the influence of different host plants on phenotype and pathogenicity of C.m. subsp. michiganensis. It is possible to propose that investigated changes were due to influence of unspecific for the bacterium host plants. The results obtained are of interest because the fact that the bacterium can directly don't attack those host plants but they could be a potential source of infection tomato plants with C.m. subsp. michiganensis.
Table 1. Pathogenicity of C.m. subsp. michiganensis isolates from different unspecific host plants.
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Number infected tomato plants after
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Host Plants 8 days 20 days 32 days
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1 3 5 7 9 1 3 5 7 9 1 3 5 7 9
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Triticum aestivum L. 25 5 - - - - 10 17 3 - - - 3 16 11
Secale cereale L. 20 10 - - - - 15 10 5 - - - 10 14 6
Hordeum vulgare Jess. 15 15 - - - - 18 6 6 - - - 12 13 5
Avena sativa L. 10 20 - - - - 12 10 6 2 - - 14 10 6
Zea mays Shert. 8 16 6 - - - 8 10 8 4 - - 6 10 14
Capsicum annuum L. 30 - - - - - 18 12 - - - 16 10 4 -
Solanum melongena L. 30 - - - - 30 - - - - 27 3 - - -
Nicotiana tabacum L. 30 - - - - 30 - - - - 27 3 - - -
Solanum tuberosum L. 28 2 - - - - 22 8 - - - 18 8 4 -
Datura sotromonium L. 30 - - - - 30 - - - - 30 - - - -
Solanum microcarpon L.30 - - - - 30 - - - - 28 2 - - -
Cucumis sativas L. 16 14 - - - 8 12 10 - - - 12 8 6 4
Citrulus aedulis Pang. 6 20 4 - - - 2 19 6 3 - 8 14 6 2
Heliantus annus L. 16 14 - - - - 2 10 6 4 - 10 10 6 4
Pisum sativum L. 30 - - - - 30 - - - - 28 2 - - -
Phaseolus vulgaris L. 30 - - - - 30 - - - - 28 2 - - -
Alium sativum L. 19 11 - - - 10 18 2 - - 10 12 8 - -
Alium cepa L. 30 - - - - 30 - - - - 27 3 - - -
Raphanus sativus var. 30 - - - - 30 - - - - 30 - - - -
radicula
Lycopersicon 6 18 6 - - - 3 10 10 7 - - 3 11 16
esculentum Mill
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+ Rating of tomato plants by Laterrot's scale (1974)
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Strider, D.L. 1969. Tech. N.C. Agricol. Exp. Stat., N. 193, 110p.
Stamova, L., V. Sotirova. 1987. Arch. Phytopathol. Pflanzenschtz., 33:211-216.
Thyr, B.D.,L.A. Samuel, P.G. Brown. 1975. Plant Dis. Rpt. v.59, n.7, 595-598.
Wallhausen, E.J. 1938. Phytopathology, 28:475-482.