Genetic diversity assessment of bread wheat ( <i>Triticum aestivum</i> L.) varieties under salinity stress using RAPD markers
Аннотация
Bread wheat (Triticum aestivum L.) is a primary staple crop in Uzbekistan, where soil salinization and water scarcity significantly constrain agricultural productivity. Identifying salt-tolerant germplasm through molecular and phenotypic screening is essential for developing resilient varieties. In this study, nine bread wheat varieties were evaluated using a completely randomized design under two treatments: control (distilled water) and salt stress (200 mM NaCl). Phenotypic assessment focused on seedling traits, including Germination Rate Index (GRI), Shoot Fresh Weight (SFW), Root Fresh Weight (RFW), Shoot Dry Weight (SDW), Root Dry Weight (RDW), and the mean Salt Tolerance Trait Index (STTI). Molecular diversity was assessed using five decamer Random Amplified Polymorphic DNA (RAPD) primers. A total of 19 polymorphic loci were amplified, showing 100% polymorphism across all markers. The primer OPC-06 exhibited the highest informativeness with a Polymorphism Information Content (PIC) of 0.86, while the average PIC across all primers was 0.64. Under 200 mM NaCl stress, the mean STTI value calculated as an average across all investigated morphological traits was 82.90%, with significant genotypic variation (p < 0.01) observed. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) cluster analysis divided the genotypes into three distinct clusters, where the variety Pakhlavon formed a genetically distinct lineage. These results demonstrate that the integration of RAPD markers and phenotypic STTI screening effectively identifies salt-tolerant genotypes. Specifically, local varieties Pakhlavon and Ok Marvarid were identified as superior genetic resources for future breeding programs aimed at improving wheat resilience in salinity-prone environments.