Evaluation of Genetic Variability within a Collection of Cumin Genotypes Using RAPD, ISSR, SRAP and SCoT Markers and Variability of In Vitro Callus Induced Therefrom

Abstract

The availability of adequate information about the documentation and characterization of germplasm is fundamental for any crop improvement program. The importance of cumin as a medicinal plant yet the lack of information about its genetic variability encouraged us to initiate the current study aiming at assessing the genetic variability among 17 cumin genotypes from different geographical regions using four molecular markers (RAPD, ISSR, SRAP and SCoT). Further, the potential of six accessions to induce callus was studied under in vitro conditions on MS and B5 basal media supplemented with various combinations between 2,4-D and kinetin. Our findings showed that combining 87 primers, including 42, 15, 7 and 23 primers of RAPD, ISSR, SCoT and SRAP, respectively, facilitated detecting the relationship among the assessed cumin accessions. A total number of 765 bands were analyzed, among which only 74 bands were polymorphic. The polymorphism was low (9.67%) and varied among and within markers. The SCoT markers exposed the highest average values of polymorphism information content (0.06), resolving power (0.91) and diversity index (0.08), while ISSR induced the highest expected heterozygosity (0.06) and marker index (0.08). The UPGMA dendrogram based on data from all the molecular markers separated the genotypes into three main clusters, with a partial geographic-based relationship among the genotypes. Out of the six accessions evaluated for callus induction in vitro, five were potent to induce callus, with a frequency ranging from 90.4 to 97.5% and no significant differences among the five accessions tested using ANOVA. Two medium combinations showed superior results: MS amended with 2,4-D (4.44 mg/L) + Kin (0.22 mg/L) and B5 with 2,4-D (8.88 mg/L) + Kin (0.22 mg/L). Statistically significant variations in the relative growth rate of the produced callus were detected among accessions, where EG-4 accessions induced the highest values, followed by EG-5. All medium combinations, including 2,4-D alone, exhibited significant superiority compared with those including both 2,4-D and Kin. Our findings exposed low variability among the studied cumin accessions, implying the real need for more effort to assess wider populations from different geographic regions together with the need for reliable diversification programs.