ISSN:
1432-2242
Keywords:
Tomato
;
RFLP
;
rDNA
;
Tobacco mosaic virus
;
Introgression
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary We studied rDNA restriction fragment length polymorphism between two tomato lines used for F1 hybrid seed production: line A, containing the Tm-1 gene responsible for tobacco mosaic virus tolerance introgressed from the wild species Lycopersicon hirsutum, and line B, a tobacco mosaic virus sensitive line. Hybridization patterns led to distinct rDNA maps with two size classes, 10.4 and 10.7 kb, in line A and a single, 8.9-kb class in line B. Size differences were located in the intergenie sequence (IGS). A highly specific 54-bp TaqI fragment was cloned from the line A IGS and used in dot blot experiments to probe total DNA from line A, line B, and their F1 hybrid. It proved capable of discriminating B from A and the hybrid. This probe could thus serve to screen inbreds in commercial seed lots where line A is used as male. This fragment showed 80–90% sequence homology with the 53-bp subrepeats previously characterized in a region of the tomato IGS close to the 25S rRNA gene. Preliminary comparison of rDNA in line A and several wild related species indicated that the L. hirsutum H2 genotype was the closest to line A. rDNA variations between line A and this wild genotype could be explained by recombination during the introgression process involving numerous backcrosses or by an important intraspecific polymorphism. Our results strongly suggest that Tm-1 and the rDNA were introgressed together into tomato from L. hirsutum through linkage drag.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00224218
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