Root-knot nematodes (Meloidogyne spp.) are an important worldwide pest of cucumber (Cucumis sativus L.). Molecular markers linked to the Javanese root-knot nematode (M. javanica) resistance gene mj in cucumber may aid marker assisted selection. One-hundred AFLP (EcoRI-MseI) and 112 SRAP were used to screen resistant and susceptible parents for polymorphisms to develop molecular markers linked to the mj gene. Of the 100 AFLP primers, 92 produced bands and two yielded candidate markers (E-ATT/M-CAA and E-AAC/M-CTG). These two bands were cut off from polyacrylamide gel, cloned and sequenced. Primers designed from the sequences did not yield polymorphic bands between the parents. In addition, the sequences did not contain any restriction site or indel to be used to convert them to CAPS or SCAR markers. The two sequences obtained from polymorphic AFLP markers were used primarily to design D1F, D1R, D17F and D17R primers. SRAP forward and reverse primers were used in combination with these four specific primers to search for polymorphisms between parents. Of the 112 primer combinations 11 yielded polymorphisms between parents. MapMaker Exp 3.0 software was used to analyze the 11 markers. Two markers were identified that flanked the mj gene at distance of 16.3 and 19.3 cM. The results indicated that these markers should be useful to develop molecular markers flanking the mj gene.

Zucchini yellow mosaic virus (ZYMV) is one of the most important pathogens that cause significant yield losses in many cucurbit crops including cucumber (Cucumis sativus L). ZYMV resistance in cucumber is inherited by a single recessive gene. The purpose of this study was to identify molecular markers linked to the gene conferring ZYMV resistance in cucumber. We developed a population of 188 F 2 plants derived from inbred cucumber lines. Individual F 2 plants were self-pollinated to generate F 3 populations. Ten randomly selected plants from each F 3 population were tested for ZYMV resistance. We used a bulk segregant analysis method to identify putative molecular markers linked to ZYMV resistance. Using bulked DNA samples with parental lines and F 1 , a total of 170 sequence-related amplified polymorphism (SRAP), 586 simple sequence repeat (SSR), and 308 amplified fragment length polymorphism (AFLP) primer combinations were screened. Neither polymorphic SRAP nor SSR markers were linked with ZYMV resistance. Among the 308 AFLP primer combinations tested, an AFLP marker in the E-ACA/MCA primer combination showed significant association among parental lines, F 1 , and resistant and susceptible plants. The combination of E-ACA/M-CA was achieved on parental lines, F 1 , and 188 F 2 individuals for confirmation of the marker segregation on the F 2 population. We found that the combination of E-ACA/M-CA was linked to the zym locus with 6.91 cM.

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Control of virus diseases such as zuchini yellow mosaic virus (ZYMV) of cucumber causing major yield and quality losses is impossible by using any chemical pesticide except for using elimination of vectors of viruses and resistant cultivar. The objectives of this study were to investigate structure of genetic resistance to ZYMV of cucumber for marker-assisted selection (MAS). Forty-eigth resistant and 48 susceptible lines were selected from a germplasm of 600 cucumber lines. Bulk DNAs of resistant and susceptible lines were screened to find candidate marker(s) by using ISSR, RAPD and a cleaved amplified polymorphism (CAP) primers, which targeted over 5000 loci of cucumber. Candidate markers later were applied to 96 lines including 48 resistance and susceptible lines to find associating markers. A total of 54 candidate marker loci were produced, which were clustered into two groups based on Dice’, average distance, simple matching and correlation similarity matrices. In the association analyses by using TASSEL software, associating markers were detected. These markers were then subjected to backward regression analysis by SAS program. The results explained %78 of total variation for ZYMV. The remaining 22% of the variation was possibly due to presence of additional gene(s) and environmental effect that caused lower repeatability.