تحلیل تنوع ژنتیکی ژنوتیپ‌های گندم نان کشت‌شده در برخی مناطق استان هرمزگان با استفاده از نشانگرهای SSR

Abstract



Introduction

Bread wheat (Triticum aestivum L.) is one of the most important cereal crops worldwide and in Iran, and understanding its genetic diversity is essential for the conservation of genetic resources, selection of suitable parents in breeding programs, and development of cultivars adapted to adverse environmental conditions. In arid and semi-arid regions such as Hormozgan Province, specific climatic conditions, environmental stresses, and seed management practices by farmers may contribute to the formation of different patterns of genetic diversity and structure. In addition, due to continuous cultivation and farmer-mediated seed recycling of these genotypes in different regions, the occurrence of intra-specific genetic variation among the collected samples is likely. Therefore, investigating native genotypes from these regions can provide valuable information for breeding and utilization of genetic resources. Among molecular markers, simple sequence repeat (SSR) markers are considered effective tools for evaluating genetic diversity due to their high polymorphism, co-dominant inheritance, accuracy, and reproducibility. The aim of this study was to investigate the genetic diversity of bread wheat genotypes collected from different regions of Hormozgan Province using SSR markers.



Materials and Methods

In this study, four bread wheat genotypes were collected from each of ten regions of Hormozgan Province during 2017–2018, and their genetic diversity was evaluated using nine pairs of SSR primers. Genomic DNA was extracted using the CTAB method, and DNA fragments were amplified through polymerase chain reaction (PCR). PCR products were separated on polyacrylamide gels and their banding patterns were analyzed. Genetic diversity indices including the number of observed alleles, effective alleles, Shannon’s index, polymorphism information content (PIC) were calculated. In addition, analysis of molecular variance (AMOVA) was performed to evaluate the distribution of genetic variation within and among groups. Genetic relationships among genotypes were assessed using Neighbor-Joining cluster analysis and principal component analysis (PCA).



Results

A total of 94 alleles were identified across nine SSR loci, with an average of 10.44 alleles per locus. The number of alleles per locus ranged from 8 to 12; primers TAA1 and CAC15 produced the highest number of alleles (12), whereas primer CAC23 generated the lowest number (8). PIC values ranged from 0.333 for primer CAC23 to 0.554 for primer TAA1, with an average value of 0.46, indicating the suitable discriminatory power of the markers used for detecting genetic diversity. Cluster analysis classified the genotypes into three major groups, and PCA results confirmed this classification. The clustering pattern showed partial agreement with the geographical origin of the samples. The highest genetic similarity was observed among the Tashkouyeh genotypes, whereas the lowest similarity was found between Mehrgan-Gahkom and Sirvan-Gahkom genotypes. This pattern may have been influenced by factors such as geographical origin, seed management, and seed exchange among farmers. AMOVA results indicated that most of the genetic variation was distributed within groups.



Conclusion

The results of this study demonstrated that bread wheat genotypes cultivated in Hormozgan Province possess considerable genetic diversity, and SSR markers were effective in detecting this diversity and revealing genetic relationships among genotypes. These findings highlight the importance of conserving native genetic resources and utilizing them in future wheat breeding programs.