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Genetics

Yellow Mosaic Symptoms Induced by Y Satellite RNA of Cucumber Mosaic Virus is Regulated by a Single Incompletely Dominant Gene in Wild Nicotiana Species. C. Masuta,Life Science Research Laboratory, Japan Tobacco Inc., 6-2 Umegaoka, Midori-ku, Yokahama 227, Japan; M. Suzuki(2), S. Kuwata(3), Y. Takanami(4), and A. Koiwai(5). (2)(3)(5)Life Science Research Laboratory, Japan Tobacco Inc., 6-2 Umegaoka, Midori-ku, Yokahama 227, Japan; (4)Laboratory of Plant Pathology, Department of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka 812, Japan. Phytopathology 83:411-413. Accepted for publication 30 November 1992. Copyright 1993 The American Phytopathological Society. DOI: 10.1094/Phyto-83-411.

Y satellite RNA (Y-satRNA) of cucumber mosaic virus (CMV) together with the helper virus induces a bright yellow symptom when inoculated on tobacco plants (Nictotiana tabacum) and develops a green mosaic symptom in N. clevelandii, while N. bigelovii exhibits a yellow symptom when inoculated with CMV-O plus Y-satRNA, even though the two wild species are very closely related to each other. N. bigelovii and N. clevelandii were crossed to analyze the symptom expression of the progeny plants. When inoculated with CMV+Y-satRNA, all the F₁ plants initially showed a faint yellow mosaic, which eventually turned into a green mosaic with traces of yellow, indicating intermediate symptoms. The symptom responses of F₂, F₃ selfed plants, and backcross plants to inoculation with CMV+Y-satRNA were also analyzed. The segregation ratios were consistent with the presence of a single incompletely dominant gene that is involved in the production of bright yellow symptoms during infection by Y-satRNA.