RFLP and RAPD mapping of the rice gm2 gene that confers resistance to biotype 1 of gall midge (Orseolia oryzae)

Gm2 is dominant gene conferring resistance to biotype 1 of gall midge (Orseolia oryzae Wood-Mason), the major dipteran pest of rice. The gene was mapped by restriction fragment length polymorphism (RFLP) analysis of a set of 40 recombinant inbred lines derived from a cross between the resistant variety Phalguna and the susceptible landrace ARC 6650. The gene is located on chromosome 4 at a position 1.3 cM from marker RG329 and 3.4 cM from RG476. Since the low (28%) polymorphism of this indica x indica cross hindered full coverage of the genome with RFLP markers, the mapping was checked by random amplified polymorphic DNA (RAPD)/bulked segregant analysis. Through the use of 160 RAPD primers, the number of polymorphic markers was increased from 43 to 231. Two RAPD primers amplified loci that co-segregated with resistance/susceptibility. RFLP mapping of these loci showed that they are located 0.7 cM and 2.0 cM from RG476, confirming the location of Gm2 in this region of chromosome 4. Use of these DNA markers will accelerate breeding for gall midge resistance by permitting selection of the Gm2 gene independently of the availability of the insect.     

Mapping a new nematode resistance locus in Lycopersicon peruvianum

Accessions of the wild tomato species L. peruvianum were screened with a root-knot nematode population (557R) which infects tomato plants carrying the nematode resistance gene Mi. Several accessions were found to carry resistance to 557R. A L. peruvianum backcross population segregating for resistance to 557R was produced. The segregation ratio of resistant to susceptible plants suggested that a single, dominant gene was a major factor in the new resistance. This gene, which we have designated Mi-3, confers resistance against nematode strains that can infect plants carrying Mi. Mi-3, or a closely linked gene, also confers resistance to nematodes at 32°C, a temperature at which Mi is not effective. Bulked-segregant analysis with resistant and susceptible DNA pools was employed to identify RAPD markers linked to this gene. Five-hundred-and-twenty oligonucleotide primers were screened and two markers linked to the new resistance gene were identified. One of the linked markers (NR14) was mapped to chromosome 12 of tomato in an L. esculentum/L. pennellii mapping population. Linkage of NR14 and Mi-3 with RFLP markers known to map on the short arm of chromosome 12 was confirmed by Southern analysis in the population segregating for Mi-3. We have positioned Mi-3 near RFLP marker TG180 which maps to the telomeric region of the short arm of chromosome 12 in tomato.     

Molecular mapping of the py-1 gene for resistance to corky root rot (Pyrenochaeta lycopersici) in tomato

 We report the molecular mapping of the py-1 gene for resistance to corky root rot [Pyrenochaeta lycopersici (Schneider and Gerlach)] in tomato using RAPD and RFLP marker analysis. DNA from near-isogenic lines (NILs) of tomato differing in corky root rot resistance was screened with 575 random oligonucleotide primers to detect polymorphic DNAs linked to py-1. Three primers (OPW-04, OPC-02, OPG-19) revealed polymorphisms between the NILs. Twelve resistant and eight susceptible DNA pools derived from segregating F₃ families were used to confirm that the RAPD markers were linked to the py-1 gene. Two of the linked amplified fragments, corresponding to OPW-04 and OPC-02, were subsequently cloned and mapped on the tomato molecular linkage map as RFLPs. These clones were located between TG40 and CT31 on the short arm of chromosome 3. Further analysis with selected RFLP markers showed that 7% (8.8 cM) of chromosome 3 of the resistant line ‘Moboglan’ was introgressed from the L. peruvianum donor parent. Three RFLP markers (TG40, TG324, and TG479) from the introgressed part of chromosome 3 were converted to cleaved amplified polymorphism (CAP) markers for use in a polymerase chain reaction (PCR) assay. These PCR markers will allow rapid large-scale screening of tomato populations for corky root rot resistance. Received: 2 January 1998 / Accepted: 12 January 1998     

Identification of RAPD markers linked to a major blast resistance gene in rice

Rice blast, caused byPyricularia grisea, is a major production constraint in many parts of the world. The Korean rice variety Tongil showed high levels of resistance for about six years when widely planted under highly disease-conducive conditions, before becoming susceptible. Tongil was found to carry a single dominant gene, designatedPi-10t, conferring resistance to isolate 106 of the blast pathogen from the Philippines. We report here the use of bulked segregant RAPD analysis for rapid identification of DNA markers linked toPi-10t. Pooled DNA extracts from five homozygous blast-resistant (RR) and five susceptible (rr) BC₃F₂ plants, derived from a CO39 × Tongil cross, were analyzed by RFLP using 83 polymorphic probes and by RAPD using 468 random oligomers. We identified two RAPD markers linked to thePi-10t locus: RRF6 (3.8 ± 1.2 cM) and RRH18 (2.9 ± 0.9 cM). Linkage of these markers withPi-10t was verified using an F2 population segregating forPi-10t. The two linked RAPD markers mapped 7 cM apart on chromosome 5. Chromosomal regions surrounding thePi-10t gene were examined with additional RFLP markers to define the segment introgressed from the donor genome.Pi-10t is likely to be a new blast-resistance locus, because no other known resistance gene has been mapped on chromosome 5. These tightly linked RAPD markers could facilitate early selection of thePi-10t locus in rice breeding programmes.     

Identification and localization of molecular markers linked to the Lr9 leaf rust resistance gene of wheat

Near-isogenic lines (NILs) for the leaf rust resistance gene Lr9 were screened for polymorphisms at the molecular level. RAPD (random amplified polymorphic DNA) primers as well as RFLP (restriction fragment length polymorphism) markers were used. Out of 395 RAPD primers tested, three showed polymorphisms between NILs, i.e., an additional band was found in resistant lines. One of these polymorphic bands was cloned and sequenced. Specific primers were synthesized, and after amplification only resistant lines showed an amplified product. Thus, these primers define a sequence-tagged site that is specific for the translocated fragment carrying the Lr9 gene. A cross between a resistant NIL and the spelt (Triticum spelta) variety Oberkulmer was made, and F₂ plants were analyzed for genetic linkage. All three polymorphisms detected by the PCR (polymerase chain reaction) and one RFLP marker (cMWG684) showed complete linkage to the Lr9 gene in 156 and 133 plants analyzed, respectively. A second RFLP marker (PSR546) was closely linked (8±2.4 cM) to the Lr9 gene and the other four DNA markers. As this marker maps to the distal part of the long arm of chromosome 6B of wheat, Lr9 and the other DNA markers also map to the distal region of 6BL. All three PCR markers detected the Lr9 gene in independently derived breeding lines and varieties, thus proving their general applicability in wheat breeding programs.     

Characterization and mapping of <Emphasis Type="Italic">Rpi1</Emphasis>, a gene that confers dominant resistance to stalk rot in maize

The maize inbred lines 1145 (resistant) and Y331 (susceptible), and the F₁, F₂ and BC₁F₁ populations derived from them were inoculated with the pathogen Pythium inflatum Matthews, which causes stalk rot in Zea mays. Field data revealed that the ratio of resistant to susceptible plants was 3:1 in the F₂ population, and 1:1 in the BC₁F₁population, indicating that the resistance to P. inflatum Matthews was controlled by a single dominant gene in the 1145×Y331 cross. The gene that confers resistance to P. inflatum Matthews was designated Rpi1 for resistance to P. inflatum) according to the standard nomenclature for plant disease resistance genes. Fifty SSR markers from 10 chromosomes were first screened in the F₂ population to find markers linked to the Rpi1 gene. The results indicated that umc1702 and mmc0371 were both linked to Rpi1, placing the resistance gene on chromosome 4. RAPD (randomly amplified polymorphic DNA) markers were then tested in the F₂population using bulked segregant analysis (BSA). Four RAPD products were found to show linkage to the Rpi1 gene. Then 27 SSR markers and 8 RFLP markers in the region encompassing Rpi1 were used for fine-scale mapping of the resistance gene. Two SSR markers and four RFLP markers were linked to the Rpi1 gene. Finally, the Rpi1 gene was mapped between the SSR markers bnlg1937 and agrr286 on chromosome 4, 1.6 cM away from the former and 4.1 cM distant from the latter. This is the first time that a dominant gene for resistance to maize stalk rot caused by P. inflatum Matthews has been mapped with molecular marker techniques.     

RAPD and RFLP mapping of the bacterial blight resistance gene xa-13 in rice

Bacterial blight (BB) caused by Xanthomonas oryzae pv oryzae (Xoo) is one of the most serious diseases of rice. The recessive gene xa-13 confers resistance to Philippine race 6 of Xoo. To tag xa-13 with molecular markers, RAPD analysis was conducted with the combined use of near-isogenic lines and bulked segregant analysis. From the survey of 260 arbitrary 10-nucleotide primers, one primer (OPAC05) was detected to amplify specifically a 0.9-kb band from the DNA of susceptible plants. The distance between the RAPD marker OPAC05-900 and xa-13 was estimated to be 5.3 cM. The RAPD marker was then mapped on chromosome 8 using a mapping population of doubled haploid lines derived from the cross of IR64/Azucena. The linkage between RFLP markers and the RAPD marker was analyzed using an F₂ population of 135 plants derived from a cross between a near-isogenic line for xa-13, IR66699-5-5-4-2, and IR24. No recombinants were found between RZ28 and CDO116 and their distance from xa-13 was estimated to be 4.8 cM. RG136 was located at 3.7 cM on the other side of xa-13. The mapping of xa-13 with closely linked DNA markers provides the basis for marker-aided selection for rice improvement.Department of Agronomy, South China Agricultural University, Guangzhou, China     

Marker enrichment and high-resolution map of the segment of potato chromosome VII harbouring the nematode resistance gene Gro1

The dominant allele Gro1 confers on potato resistance to the root cyst nematode Globodera rostochiensis. The Gro1 locus has been mapped to chromosome VII on the genetic map of potato, using RFLP markers. This makes possible the cloning of Gro1 based on its map position. As part of this strategy we have constructed a high-resolution genetic map of the chromosome segment surrounding Gro1, based on RFLP, RAPD and AFLP markers. RAPD and RFLP markers closely linked to Gro1 were selected by bulked segregant analysis and mapped relative to the Gro1 locus in a segregating population of 1105 plants. Three RFLP and one RAPD marker were found to be inseparable from the Gro1 locus. Two AFLP markers were identified that flanked Gro1 at genetic distances of 0.6 cM and 0.8 cM, respectively. A genetic distance of 1 cM in the Gro1 region corresponds to a physical distance of ca. 100 kb as estimated by long-range restriction analysis. Marker-assisted selection for nematode resistance was accomplished in the course of constructing the high-resolution map. Plants carrying the resistance allele Gro1 could be distinguished from susceptible plants by marker assays based on the polymerase chain reaction (PCR).     

Characterization of the Aspergillus niger pelB gene: structure and regulation of expression

Summary Nearly isogenic lines (NILs) of rice (Oryza sativa) differing at a locus conferring resistance to the pathogen Xanthomonas oryzae pv. oryzae were surveyed with 123 DNA markers and 985 random primers using restriction fragment length plymorphism (RFLP) and random amplified polymorphic DNA (RAPD) analysis. One chromosome 11 marker (RG103) detected polymorphism between the NILs that cosegregated with Xa21. All other chromosome 11 DNA markers tested were monomorphic between the NILs, localizing the Xa21 introgressed region to an 8.3 cM interval on chromosome 11. Furthermore, we identified two polymerase chain reaction (PCR) products (RAPD2148 and RAPD818) that detected polymorphisms between the NILs. Genomic sequences hybridizing with RAPD818, RAPD248 and RG103 were duplicated specifically in the Xa21 NIL. All three markers cosegregated with the resistance locus, Xa21, in a F₂ population of 386 progeny. Based on the frequency with which we recovered polymorphic Xa21-linked markers, we estimated the physical size of the introgressed region to be approximately 800 kb. This estimation was supported by physical mapping (using pulsed field gel electrophoresis) of the sequences hybridizing with the three Xa21-linked DNA markers. The results showed that the three Xa21-linked markers are physically close to each other, with one copy of the RAPD818 sequences located within 60 kb of RAPD248 and the other copy within 270 kb of RG103. None of the enzymes tested generated a DNA fragment that hybridized with all three of the markers indicating that the introgressed region containing the resistance locus Xa21 is probably larger than 270 kb.     

Tagging and combining bacterial blight resistance genes in rice using RAPD and RFLP markers

Four genes of rice,Oryza sativa L., conditioning resistance to the bacterial blight pathogenXanthomonas oryzae pv.oryzae (X. o. pv.oryzae), were tagged by restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) markers. No recombinants were observed betweenxa-5 and RFLP marker lociRZ390, RG556 orRG207 on chromosome 5.Xa-3 andXa-4 were linked to RFLP locusXNpb181 at the top of chromosome 11, at distances of 2.3 cM and 1.7 cM, respectively. The nearest marker toXa-10, also located on chromosome 11, was the RAPD locusO07 ₂₀₀₀ at a distance of 5.3 cM. From this study, the conventional map [19, 28] and two RFLP linkage maps of chromosome 11 [14, 26] were partially integrated. Using the RFLP and RAPD markers linked to the resistance genes, we selected rice lines homozygous for pairs of resistance genes,Xa-4 +xa-5 andXa-4 +Xa-10. Lines carryingXa-4 +xa-5 andXa-4 +Xa-10 were evaluated for reaction to eight strains of the bacterial blight pathogen, representing eight pathotypes and three genetic lineages. As expected, the lines carrying pairs of genes were resistant to more of the isolates than their single-gene parental lines. Lines carryingXa-4 +xa-5 were more resistant to isolates of race 4 than were either of the parental lines (quantitative complementation). No such effects were seen forXa-4 +Xa-10. Thus, combinations of resistance genes provide broader spectra of resistance through both ordinary gene action expected and quantitative complementation.     

RFLP and RAPD mapping of the sunflower Pl1 locus for resistance to Plasmopara halstedii race 1

The Pl1 locus in sunflower, Helianthus annuus L., conferring resistance to downy mildew, Plasmopara halstedii, race 1 has been located in linkage group 1 of the consensus RFLP map of the cultivated sunflower. Bulked segregant analyses were used on 135 plants of an F₂ progeny from a cross between a downy mildew susceptible line, GH, and RHA266, a line carrying Pl1. Two RFLP markers and one RAPD marker linked to the Pl1 locus have been identified. The RFLP markers are located at 5.6 cM and 7.1 cM on either side of Pl1. The RAPD marker is situated at 43.7 cM from Pl1. The significance and applications of these markers in sunflower breeding are discussed.     

SCAR,RAPD and RFLP markers linked to a dominant gene (Are) conferring resistance to anthracnose in common bean

Anthracnose, caused by the fungusColletotrichum lindemuthianum, is a severe disease of common bean (Phaseolus vulgaris L.) controlled, in Europe, by a single dominant gene,Are. Four pairs of near-isogenic lines (NILs) were constructed, in which theAre gene was introgressed into different genetic backgrounds. These pairs of NILs were used to search for DNA markers linked to the resistance gene. Nine molecular markers, five RAPDs and four RFLPs, were found to discriminate between the resistant and the susceptible members of these NILs. A backcross progeny of 120 individuals was analysed to map these markers in relation to theAre locus. Five out of the nine markers were shown to be linked to theAre gene within a distance of 12.0 cM. The most tightly linked, a RAPD marker, was used to generate a pair of primers that specifically amplify this RAPD (sequence characterized amplified region, SCAR).The research was supported by the CNRS and the Ministère Français de l'Education Nationale     

High-resolution genetic mapping of the pepper (Capsicum annuum L.) resistance loci Me3 and Me4 conferring heat-stable resistance to root-knot nematodes (Meloidogyne spp.)

The PM687 line of Capsicum annuum L. has a single dominant gene, Me ₃ , that confers heat-stable resistance to root-knot nematodes (RKN). Me ₃ was mapped using doubled-haploid (DH) lines and F₂ progeny from a cross between the susceptible cultivar ’Yolo Wonder’ (’YW’) and the highly resistant line ’PM687’. Bulked-segregant analysis with DNA pools, from susceptible or resistant DH lines, was performed to identify RAPD and AFLP markers linked to Me ₃ . There was no polymorphism between bulks of ten DH lines using over 800 RADP primers (4,000 amplified fragments analysed). Using 512 AFLP primers (74,000 amplified fragments analysed), and bulked DNA templates from 20 resistant and 20 susceptible plants, we identified eight repulsion-phase and four coupling-phase markers linked to Me _3. Analysed in 103 DH progeny, they defined a 56.1-cM interval containing the target gene. The nearest were located 0.5, 1.0, 1.5 and 3.0 centimorgans (cM) on both sides of the gene. Analysis of the F₂ progeny (162 plants) with the nearest coupling-phase marker confirmed its close position. Another resistance gene to RKN, present in ’PM687’ (Me ₄ ), was shown to be linked to Me ₃ , 10 cM from it. In order to localize Me ₃ and Me ₄ on our reference intraspecific pepper linkage map, two AFLP markers were mapped. The Me ₃ nearest marker was 10.1cM from a RAPD marker named Q04_0.3 and 2.7cM from a RFLP marker named CT135. We investigated map-position orthologies between Me ₃ and two other nematode resistance genes, the tomato Mi-3 and the potato Gpa ₂ genes, which mapped in the telomeric region of the short arm of the tomato and potato chromosome 12 (or XII for potato). Received: 23 March 2000 / Accepted: 2 January 2001     

Isolation and characterization of RAPD-based markers linked to the beet cyst nematode resistance locus (Hs1 pat-1) on chromosome 1 of B. patellaris

A beet cyst nematode (BCN)-resistant telosomic addition of B. patellaris chromosome 1 in B. vulgaris was used to isolate 6 RAPD markers linked to the BCN resistance locus Hs1 ^pat-1. Southern analysis showed that the analyzed RAPD products contain either low-, middle or high-repetitive DNA. The relative positions of the random amplified polymorphic DNA (RAPD) markers and of the restriction fragment length polymorphism (RFLP) loci corresponding to the low-repetitive RAPD products were determined by deletion mapping using a panel of seven nematode-resistant B. patellaris chromosome-1 fragment additions. One RAPD marker, OPB11₈₀₀, was found to be present in two copies on the long arm telosome of B. patellaris chromosome 1. These copies are closely linked to the BCN resistance gene and flank the gene on both sides. On the basis of the nucleotide sequence of OPB11₈₀₀, sequence-tagged site (STS) primers were developed that amplify specific fragments derived from the two OPB11₈₀₀ loci. These STS markers can be used in the map-based cloning of the BCN gene, as they define start and finishing points of a chromosomal walk towards the Hs1 ^pat-1 locus. Two copies of the middle-repetitive OPX2₁₁₀₀ marker were mapped in the same interval of the deletion mapping panel as the resistance gene locus and thereby belong to the nearest markers as yet found for the BCN gene in B. patellaris.     

A detailed linkage map around an apple scab resistance gene demonstrates that two disease resistance classes both carry the V f gene

A detailed genetic map has been constructed in apple (Malus x domestica Borkh.) in the region of the v _f gene. This gene confers resistance to the apple scab fungus Venturia inaequalis (Cooke) Wint. Linkage data on four RAPD (random amplified polymorphic DNA) markers and the isoenzyme marker PGM-1, previously reported to be linked to the v _f gene, are integrated using two populations segregating for resistance to apple scab. Two new RAPD markers linked to v _f (identified by bulked segregant analysis) and a third marker previously reported as being present in several cultivars containing v _f are also placed on the map. The map around v _f now contains eight genetic markers spread over approximately 28 cM, with markers on both sides of the resistance gene. The study indicates that RAPD markers in the region of crab apple DNA introgressed with resistance are often transportable between apple clones carrying resistance from the same source. Analysis of co-segregation of the resistance classes 3A (weakly resistant) and 3B (weakly susceptible) with the linked set of genetic markers demonstrates that progeny of both classes carry the resistance gene.This work was supported in part by grants from the New Zealand Foundation for Research Science and Technology (FoRST) Programme 94-HRT-07-366 and ENZA New Zealand (International)     

Restriction fragment length polymorphism analysis of loci associated with disease resistance genes and developmental traits in Pisum sativum L.

An F₂ population of pea (Pisum sativum L.) consisting of 174 plants was analysed by restriction fragment length polymorphism (RFLP) and random amplified polymorphic DNA (RAPD) techniques. Ascochyta pisi race C resistance, plant height, flowering earliness and number of nodes were measured in order to map the genes responsible for their variation. We have constructed a partial linkage map including 3 morphological character genes, 4 disease resistance genes, 56 RFLP loci, 4 microsatellite loci and 2 RAPD loci. Molecular markers linked to each resistance gene were found: Fusarium wilt (6 cM from Fw), powdery mildew (11 cM from er) and pea common Mosaic virus (15 cM from mo). QTLs (quantitative traits loci) for Ascochyta pisi race C resistance were mapped, with most of the variation explained by only three chromosomal regions. The QTL with the largest effect, on chromosome 4, was also mapped using a qualitative, Mendelian approach. Another QTL displayed a transgressive segregation, i.e. the parental line that was susceptible to Ascochyta blight had a resistance allele at this QTL. Analysis of correlations between developmental traits in terms of QTL effects and positions suggested a common genetic control of the number of nodes and earliness, and a loose relationship between these traits and height.     

High-resolution genetic map of the Lv resistance locus in tomato

 Bulked segregant analysis and high-resolution mapping were used to pinpoint the position of the Lv gene for resistance to Leveillula taurica in tomato. Mapping in an F₂, corresponding to more than 3800 gametes, indicates that Lv is positioned within the 0.84-cM interval defined by the RFLP markers CT121 and CT129, with the closest marker, CT121, being only 0.16 cM from the gene. The tight linkage of these markers demonstrates their usefulness in marker-assisted breeding for Lv, and the high-resolution map provides a starting a starting point for positional cloning of this resistance gene. Received: 25 February 1997 / Accepted: 21 March 1997     

RFLP and RAPD markers linked to the rosy leaf curling aphid resistance gene (Sd1) in apple

 Sd ₁ is a dominant gene for resistance to biotypes 1 and 2 of the rosy leaf curling aphid, Dysaphis devecta Wlk., which can cause economic damage to apple trees. This report describes the identification of three RFLP and four RAPD markers linked to Sd ₁ in a cross between the D. devecta susceptible variety ‘Prima’ (sd ₁ sd ₁) and the resistant variety ‘Fiesta’ (Sd ₁ sd ₁). Potted trees were artificially infested in the glasshouse, and the ratio of resistant:susceptible plants supported the hypothesis that the resistance was under the control of a single dominant gene. The position of the gene was mapped to a single locus on a ‘Fiesta’ chromosome, within 2 cM of three tightly linked RFLP markers (MC064a, 2B12a and MC029b); the four RAPD markers were located further away (between 13 and 46 cM). This is the first report of molecular markers for an aphid resistance gene in tree fruit crops. The potential application of these markers in a marker-assisted resistance breeding programme is discussed. Received: 1 July 1996/Accepted: 23 August 1996     

A major locus for submergence tolerance mapped on rice chromosome 9

Submergence stress is a widespread problem in rice-growing environments where drainage is impeded. A few cultivars can tolerate more than 10 days of submergence, but the genes conferring this tolerance have not been identified. We used randon-amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) markers to map submergence tolerance in 169 F₂ plants and the resulting F₃ families of a cross between a tolerant indica rice line, IR40931-26, and a susceptible japonica line, PI543851. IR40931-26 inherited strong submergence tolerance from the unimproved cultivar FR13A. Eight-day old F₃ seedlings were submerged for 14–16 days in 55-cm deep tanks, and tolerance was scored after 7 days recovery on a scale of 1 (tolerant) to 9 (susceptible). The tolerant and susceptible parents scored 1.5 and 8.4, respectively, and the F₃ means ranged from 1.6 to 8.9. Two bulks were formed with DNA from F₂ plants corresponding to the nine most tolerant and the nine most susceptible F₃ families. Of 624 RAPD primers used to screen the bulks, five produced bands associated with either tolerance or susceptibility. These markers were mapped to a region of chromosome 9 by linkage to RFLP markers. A submergence tolerance quantitative trait locus (QTL), here designatedSub1, was located ca. 4 cM from the RFLP marker C1232 and accounted for 69% of the phenotypic variance for the trait.     

RAPD markers for constructing intraspecific tomato genetic maps

The existing molecular genetic maps of the tomato, Lycopersicon spp, are constructed based on isozyme and RFLP polymorphisms between tomato species. These maps are useful for certain applications but have few markers that exhibit sufficient polymorphisms for intraspecific analysis and manipulations within the cultivated tomato. The purpose of this study was to investigate the relative potential of RAPD technology, as compared to isozymes and RFLPs, to generate polymorphic DNA markers within cultivated tomatoes. Sixteen isozymes and 25 RFLP clones that were known to detect polymorphism between L. esculentum and L. pennellii, and 313 random oligonucleotide primers were examined. None of the isozymes and only four of the RFLP clones (i.e., 16%) revealed polymorphism between the cultivated varieties whereas up to 63% of the RAPD primers detected one or more polymorphic DNA fragments between these varieties. All RAPD primers detected polymorphism between L. esculentum and L. pennellii genotypes. These results clearly indicate that RAPD technology can generate sufficient genetic markers exploiting sequence differences within cultivated tomatoes to facilitate construction of intraspecific genetic maps.Abbreviations RFLP restriction fragments length polymorphism - RAPD random amplified polymorphic DNA - PCR polymerase chain reaction - QTLs quantitative trait loci