Interspecific hybridization in <i>Thymus</i> species: molecular and morphological characterization

Background: Thyme is a famous medicinal plant from the Lamiaceae family, which is grown in the wild throughout Iran and has one of the world's top ten essential oils.Objective: In this study, four species of the Thymus genus including T. lancifolius, T. daenensis, T. vulgaris, T. kotschyanus were crossed.Out of about 2,000 crosses, 70 seeds were obtained.Molecular and morphological assessments were done on hybrid seeds.Parents and hybrids were compared in terms of some morphological traits.Methods: DNA from leaf samples of both parents and hybrids were extracted.SSR markers including 23 pairs of primers and ISSR markers with 20 primers were used for hybrid identification.Out of 23 primers used for SSR analysis, five primers yielded scorable amplified products for hybrids in their respective parental lines.Results: Stem length in hybrids increased, and internode length decreased.Primer LT12, with 66.66% identification, was introduced as the best primer for hybrid identification.Also, out of 19 ISSR primers, five primers confirmed hybrids and their parents.Primer ISCS43 with 100% ability to identify hybrids was introduced as the best primer.Conclusion: In general, all hybrids characterized by morphological characters were supported by the ISSR and SSR data.These results indicate that ISSR and SSR data will be valuable tools to verify hybrids.