RESUMEN
BACKGROUND: Aegilops tauschii Coss. as a donor of wheat D genome has an important role in wheat breeding programs. Genetic and phylogeographic diversity of 79 Ae. tauschii accessions collected from north and northwest of Iran were analyzed based on retroelement insertional polymorphisms using inter-retrotransposon amplified polymorphism (IRAP) and retrotransposon-microsatellite amplified polymorphism (REMAP) markers. RESULTS: In total, 306 and 151 polymorphic bands were amplified in IRAP and REMAP analyses, respectively. As a result, a high level of polymorphism was observed among the studied accessions as revealed by an average of 25.5 bands per primer/primer combination and mean PIC value of 0.47 in IRAP and an average of 25.16 bands per primer combination and mean PIC value of 0.47 in REMAP. Genetic relationships of the accessions were analyzed using distance- and model-based cluster analyses. CONCLUSION: The result showed that genetic distance did not seem to be related to geographic distribution, and the accessions could be divided into three groups, which was further supported by principal coordinate analysis. These results on genetic diversity and population structure of Ae. tauschii in Iran should provide important knowledge on genetic resources and their applications in wheat breeding programs.
RESUMEN
Selection and breeding for drought tolerance in rice have always been one of the leading objectives for rice breeders in water-deficient farming areas. In the present study, we applied the potential of recombinant inbred lines (RILs) population, which were derived from cross Shahpasand (Iranian landrace) and IR28, for the development of drought-tolerant rice lines. One hundred fifty-two lines along with five check varieties were investigated from 2017 to 2019 under non-stress and drought stress conditions. The yield reduction caused by drought based on overall mean during 2017, 2018, and 2019 were estimated to be 89.40, 57.95, and 35.31%, respectively. Using different statistical methods, certain lines, including L33, L90, and L109, which are considered as the best lines in most environments, were found to be promising for being utilized to increase rice drought tolerance. The averages of grain yield of the above-mentioned lines were respectively 6.45, 5.80, and 5.70 t ha-1 under non-stress condition, and respectively 2.77, 2.66, and 2.59 t ha-1 under drought stress condition. The yield reduction of the selected lines were significantly lower than that of others indicating the significant transgressive segregation. The results revealed using the combination of the best identified tolerance and susceptibility indices and GT-biplot are effective methods for screening superior lines. However, their utilization is not easy and requires specialized packages. For the first time, we introduced a new composite index as a combination of significant indices (CSI). CSI is in the form of a linear function of indices which effectiveness is determined by their correlation coefficient with grain yield. According to our results, using CSI, the identified rice drought-tolerant lines were in high agreement with those obtained by other methods, demonstrating that CSI is a simple but reliable composite index.
RESUMEN
Knowledge in the area of genetic diversity could aid in providing useful information in the selection of material for breeding such as hybridization programs and quantitative trait loci mapping. To this end, 50 Nicotiana tabacum genotypes were genotyped with 21 primer combination of amplified fragment length polymorphism (AFLP). A total of 480 unambiguous DNA fragments and 373 polymorphic bands were produced with an average of 17.76 per primer combination. Also, the results revealed high polymorphic rate varing from 52.63 to 92.59%, demonstrating that AFLP technique utilized in this research can be a powerful and valuable tool in the breeding program of N. tabacum. Cluster analysis based on complete linkage method using Jaccard's genetic distance, grouped the 50 tobacco genotypes into eight clusters including three relatively big clusters, one cluster including Golden gift, Burly 7022 and Burly Kreuzung, one cluster consisting of two individuals (Pereg234, R9) and three single-member clusters (Pennbel69, Coker176 and Budisher Burley E), Recent genotypes showed high genetic distance from other genotypes belonging to cluster I and II. Association analysis between seven important traits and AFLP markers were performed using four statistical models. The results revealed the model containing both the factors, population structure (Q) and general similarity in genetic background arising from shared kinship (K), reduces false positive associations between markers and phenotype. According to the results nine markers were determined that could be considered to be the most interesting candidates for further studies.
