Deletion of a large genomic segment in tobacco varieties that are resistant to potato virus Y (PVY) |
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Authors: | Noguchi S Tajima T Yamamoto Y Ohno T Kubo T |
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Institution: | (1) Leaf Tobacco Research Laboratory, Japan Tobacco Inc., 1900 Idei, Oyama, Tochigi, 323-0808, Japan e-mail: nog1@d1.dion.ne.jp Tel.: +81-285-25-7078; Fax: +81-285-25-4460, JP;(2) Kagoshima Leaf Tobacco Technical Center, Japan Tobacco Inc., 5648-2 Kamifukumoto-cho, Kagoshimashi, Kagoshima, Japan, JP;(3) Plant Breeding and Genetics Laboratory, Japan Tobacco Inc., 700 Higashibara, Toyoda-cho, Shizuoka 438-0802, Japan, JP |
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Abstract: | Recessive alleles (va, va
1
, va
2
, etc) of the tobacco Va locus confer resistance to potato virus Y (PVY). To elucidate the mechanism underlying this resistance, we attempted to identify
randomly amplified polymorphic (RAPD) markers that reveal polymorphism between two nearly isogenic lines (NILs) that differ
in their susceptibility to PVY. Using each of 500 primers and 800 pairs of primers, we identified over 100 RAPD fragments
that differed between the NILs. We applied these RAPD primers or primer combinations to an F2 population obtained from a cross between the susceptible line BY4 and the resistant va
2
-bearing NIL, F55. It was found that only 10 RAPD markers were polymorphic between resistant and susceptible plants. Unexpectedly,
these markers were all linked to Va. All 10 RAPD markers were present in all 8 susceptible varieties tested. At least one RAPD marker was not detected in 8 out
of 10 resistant varieties. Southern analysis revealed that the sequences of markers were not present in the genomes of resistant
varieties, and the markers were found in individually distinct positions on the chromosomes of susceptible tobacco varieties.
These results strongly suggest that the resistance conferred by va is due to deletions at the Va locus governing susceptibility to PVY.
Received: 20 May 1999 / Accepted: 17 August 1999 |
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Keywords: | Recessive resistance Potato virus Y Randomly amplified polymorphic DNA (RAPD) Nicotiana tabacum L |
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