RESUMO
Background: the tan spot disease of wheat caused by Pyrenophera tritici-repentis has become a major disease in most wheat growing areas worldwide
Objectives: here we used ISSR and RAPD markers to study the genetic diversity of 34 P. tritici-repentis isolates collected from North of Iran
Materials and Methods: the leaves having the typical symptoms of tan spot disease were collected and after fungal isolation, purification and identification, DNAs were extracted. After PCR amplification using each primer, PCR products were run in agarose gels, and the resulting bands were scored. Cluster analysis was performed using Un-Wighted Nighbor Joining method
Results: a total of 178 reproducible bands were scored. Out of which 115 [65%] were polymorphic corresponding to an average of 8 polymorphic bands per primer. The average PIC values for ISSR and RAPD markers were 0.38 and 0.43, respectively. A high degree of genetic variability among Iranian P. tritici-repentis isolates was identified. Cluster analysis based on un-weighted neighbor-joining method using the combined molecular data revealed five distinct clusters. The results from the cluster analysis indicated that the genetic similarity among the Iranian P. tritici-repentis isolates could be partly explained by geographic origins where the isolates were collected
Conclusions: genetic variability of P. tritici-repentis along with relatively high level of geographic diversity observed in this study may suggest longer evolutionary period for the isolates from the Middle East, wheat center of origin, as opposed to other places
RESUMO
Background: downy mildew caused by Plasmopara halstedii is a devastating disease in sunflower worldwide. Several dominant resistance genes designated as Pl have been identified and linked molecular markers have been demonstrated. However, no information on theresistance genes is available forIranian lines
Objectives: the presence of three map-based molecular markers previously proved to be linked to different resistance genes were evaluated in sunflower inbred lines
Materials and Methods: using PCR-based and CAPS molecular markers, 26 sunflower inbred lines with different responses to P. halstedii race 100 were used to detect the presence of three resistance loci including Pl[1], Pl[6]and Pl[13] within the lines
Results: molecular marker linked to Pl[13] was present in some of the sunflower lines but was not correlated with the phenotypic reaction of the lines to race 100. Despite the use of three markers linked to Pl[6], PCR failed to amplify any corresponding product. This data may suggest that none of the genotypes possessed Pl[6] locus. Pl[1]-linked cleaved amplified polymorphic sequences [CAPS] were present in several resistance lines and effectively differentiated susceptible and resistant sunflower lines
Conclusions: applicability of molecular markers in breeding programs revisited in disease management