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Etiology

Association Between Tobacco Streak Ilarvirus Seed Transmission and Anther Tissue Infection in Bean. M. H. Walter, Graduate student, Department of Plant Pathology, Washington State University (WSU), Pullman, WA 99164-6430, Present address: Department of Plant Pathology, Throckmorton Hall, Kansas State University, Manhattan, KS 66506-5502; W. J. Kaiser(2), R. E. Klein(3), and S. D. Wyatt(4). (2)Research plant pathologist, U.S. Department of Agriculture, Agricultural Research Service, Western Regional Plant Introduction Station, WSU, Pullman, WA 99164-6402; (3)Assistant plant pathologist, Irrigated Agriculture Research and Extension Center, WSU, Rt. 2, Box 2953-A, Prosser, WA 99350-9687; (4)Associate professor, Department of Plant Pathology, Washington State University (WSU), Pullman, WA 99164-6430. Phytopathology 82:412-415. Accepted for publication 18 December 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/Phyto-82-412.

Tobacco streak ilarvirus (TSV) seed transmission was investigated by reciprocal pollinations as well as by serological and infectivity assays of flower parts from beans (Phaseolus vulgaris) systemically infected with either TSV pathotype I (isolate Mel 40) or TSV pathotype II (isolate Mel F). Healthy and TSV-infected Black Turtle Soup (BTS) bean plants were reciprocally pollinated by using anthers from either healthy plants or plants systemically infected with Mel 40 or Mel F. When anthers from plants infected with Mel 40 were used to pollinate healthy plants, a high percentage of the resulting seedlings were infected with that isolate. Similar results were obtained from plants infected with Mel 40 that were allowed to self-pollinate. Seed populations from pollinations that used anthers from healthy plants and ovaries from infected plants produced much lower seedling infection. The Mel F isolate was not seed-transmitted in cross-pollination experiments with BTS. Enzyme-linked immunosorbent assay results indicated that antigen levels of the two virus isolates were similar in flower petals and in ovaries of beans infected with either virus. However, TSV Mel 40 mean antigen levels in stamen tissues were much higher than those of TSV Mel F in similar tissues. The amount of infectious virus as measured by infectivity assays of flower parts on the local lesion host Chenopodium quinoa was also greater in stamens of plants infected with TSV Mel 40 than in stamens of plants infected with TSV Mel F. Seed transmission of TSV in beans may depend on early movement into and replication in pollen-associated tissues.