Document Type : Research Paper
Authors
1
Department of Food Biotechnology, Branch for Northwest and West Region, Agricultural Biotechnology Research Institute of Iran, Agricultural Research, Education and Extension Organization (AREEO), Tabriz, Iran
2
2Researcher, Branch for Northwest & West Region, Agricultural Biotechnology Research Institute of Iran (ABRII), Agricultural Research, Education and Extension Organization (AREEO), Tabriz, Iran.
3
Branch for Northwest & West region, Agricultural Biotechnology Research Institute of Iran (ABRII), Agricultural Research, Education and Extension Organization (AREEO), Tabriz, Iran
10.22092/ijrfpbgr.2025.370344.1480
Abstract
Background and Objectives: Knowledge of genetic diversity in forage plants is crucial for breeding and developing synthetic varieties with optimal adaptability and performance. Smooth bromegrass (Bromus inermis Leyss.), due to its relatively high resistance to drought and unfavorable climatic conditions, holds particular importance in the semi-steppe rangelands of Iran. Assessing the level of genetic diversity in forage grasses is essential for parent selection in breeding programs, and the use of molecular markers reduces both the time and cost of these projects. This study aimed to investigate the genetic diversity and determine the degree of similarity among 20 selected genotypes of smooth bromegrass using ISSR molecular markers, to identify suitable genotypes for breeding improved varieties.
Materials and Methods: Twenty genotypes of smooth bromegrass, previously selected from domestic and foreign germplasm resources, were evaluated using 34 ISSR primers. DNA was extracted from leaf tissue, and its quality and quantity were assessed using a NanoDrop device. Polymerase chain reaction (PCR) was performed under optimized conditions, and the resulting products were electrophoresed on agarose gel. Presence or absence of bands was recorded as a binary matrix. Marker efficiency was determined by calculating polymorphism information content (PIC), including percentage of polymorphic loci, effective number of alleles (Ne), Shannon's index (I), and expected heterozygosity (He). Genetic structure was analyzed using UPGMA clustering based on Jaccard’s coefficient and principal component analysis (PCA). All computations were conducted using MEGA, POPGENE software, and R packages.
Results: A total of 400 alleles were identified, of which 355 were polymorphic, indicating high genetic diversity among the genotypes. Diversity indices revealed moderate to high genetic variation, with an average effective number of alleles of 1.533, Shannon's index of 0.447, and expected heterozygosity of 0.315. Cluster analysis grouped the genotypes into four clusters, with the fourth
cluster exhibiting the highest diversity and identified as a potential source for introducing new traits through targeted crosses. The results of PCA also confirmed these groupings, highlighting considerable genetic divergence among genotypes. ISSR markers were recognized as a highly efficient, cost-effective, and reproducible tool for genetic analysis this plant species.
Conclusion: ISSR24, ISSR07, ISSR06, ISSR13, ISSR14, and ISSR35 markers produced the highest number of clear, repeatable, and polymorphic bands, making them suitable, cost-effective tools for investigating genetic diversity in smooth bromegrass and applicable in breeding programs aimed at improving forage yield. Eight to twelve superior genotypes-including B.in06, B.in14, B.in19, B.in17, B.in12, B.in16, B.in08, and B.in15-were identified across three clusters with appropriate genetic distances, providing a foundation for creating improved synthetic varieties.
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