Determination of genetic diversity in some Tunisian citrus varieties using molecular markers

Citrus is one of the most important fruit plants consumed all over the world. Tunisia is well known for its Citrus fruits production which have a big importance in agricultural and medicinal sector. In this study, genetic variation among 36 Citrus genotypes of which 8 were developed in Tunisia were determined using two molecular markers: ISSR and SCOT. The 10 ISSR primers generated a total of 270 clear and reproducible bands (ranged between 250 and 3888 bp), of which 268 were polymorphic (99.2%). On the other hand, 10 SCOT primers amplified a total of 240 reproducible bands (ranged between (150 and 3357 bp), of which 228 were polymorphic (95%). Average polymorphism information content was calculated as 0.249 for ISSR, and 0.27 for SCOT primers. The highest pairwise genetic similarity obtained from ISSR analysis was between Powell and Novalina (0.545) and lowest pairwise genetic similarity was between Aforer and Panacher (0.102). Whereas SCOT analysis indicated that the genetically most close varieties were Orange Lane Late and Novalina (0.615), and least close varieties were Eureka and Tomatera (0.169). Additionally, UPGMA dendrograms revealed the different levels of sub clustering that separated varieties according to the respective Citrus group and allowed for the discrimination of all the genotypes. The results of this study showed that genetic diversity and relationships among Citrus varieties could be successfully determined by ISSR and SCOT markers for breeding programs. Keywords: Citrus, Genetic variation, Molecular markers, SCOT, ISSR