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Mapping the Root-Knot Nematode Resistance Gene (Rk) in Tobacco with RAPD Markers

December 1998 , Volume 82 , Number  12
Pages  1,319 - 1,322

H.-Y. Yi , R. C. Rufty , and E. A. Wernsman , Department of Crop Science ; and M. C. Conkling , Department of Genetics, North Carolina State University, Raleigh 27695-7620

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Accepted for publication 17 August 1998.

Random amplified polymorphic DNA (RAPD) analysis was conducted to map the Rk gene in tobacco which conditions resistance to races 1 and 3 of the root-knot nematode, Meloidogyne incognita. Resistant burley tobacco genotype NC 528, containing the Rk gene, and the susceptible cultivar Ky 14 were screened with 1,500 random decamers. A low rate of genetic polymor-phism (<10%) was detected among these lines. Two populations (F1 and F3) of maternally de-rived doubled haploid (MDH) lines of burley tobacco, developed from the cross NC 528 × Ky 14, were used to map the Rk gene. NC 528, Ky 14, three Rk-resistant (Rk-R) DNA bulks, andthree Rk-susceptible (Rk-S) bulks generated from F1-derived MDH individuals were screenedwith the primers that amplified bands polymorphic between Rk-R and Rk-S lines. A total of 67 F1MDH lines and 59 F3MDH lines were screened with the primers that amplified bands polymorphic between Rk-R bulks and Rk-S bulks to confirm linkage between candidate markers and the Rk gene. Sixteen RAPD markers were positioned at six loci in a map 24.1 centimorgans long. Six RAPD markers, including one identified in the F3MDH population, were mapped at the Rk locus.

Additional keywords: disease resistance, linkage analysis, Meloidogyne incognita, Nicotiana tabacum

© 1998 The American Phytopathological Society