Molecular characterization of tomato (Solanum lycopersicum L.) landraces under drought stress

Abstract Exploring the genetic diversity among plant landraces is important for the conservation and management of plant genetic resources. In this study, a collection of forty–six tomato landraces was evaluated based on the morpho-physiological, and molecularly characterize to detect the genetic diversity. Tomato landraces seedlings were exposed to drought stress with 70% field capacity and 40% field capacity under field conditions. Drought stress had significantly negatively influenced root dry weight, root fresh weight, root growth rate, shoot fresh weight, shoot dry weight, and shoot growth rate. Moreover, proline content showed a highly significant increase in response to drought stress. The analysis of twenty morphological characters revealed a wide range of variations among tomato landraces. Landraces were screened with fourteen SSRs primers, among them six primers were used to determine the genetic diversity and genetic relationship. Based on resolving power, primer LEct004 and LEat018 were most significant as they can recognize all 46 landraces. The LEct004 SSRs marker had the highest PIC, while the Asr2 marker had the lowest PIC value. The landraces were grouped into two main clusters of which some are closely related while some are significantly distinct. Interestingly, the SSR markers were associated with genes e.g. LEat018 with ACTIN–RELATED PROTEIN gene, the LEct004 with the HOMEOBOX PROTEIN TRANSCRIPTION FACTORS gene, and Asr2 with ABA/WDS. Moreover, the AUXIN RESPONSE FACTOR8 gene was associated with the LEta014 SSR marker and the LEta020 with the THIOREDOXIN FAMILY TRP26 gene. The genetic diversity analysis and functional annotations of the Gene-Associated SSRs information obtained in this study provide useful information that can be implemented in the breeding programs.