Genetic diversity of some thornless blackberry genotypes using ISSR molecular markers

Abstract

Genetic diversity in blackberries is crucial for improving quality and yield. This study evaluates thornless blackberry genotypes using 26 morphological traits and 19 inter simple sequence repeats (ISSR) markers to assess diversity and genetic relationships. A total of 28 blackberry genotypes, including both thorny and thornless types, were analyzed. Fourteen ISSR primers were selected from a pool of 19 based on their capacity to generate polymorphic bands. The findings highlight the efficiency of ISSR markers in distinguishing thorny and thornless blackberry genotypes at the subgenus level, effectively differentiating chimera-derived thornless samples. A total of 406 bands were produced, of which 402 were polymorphic. The average percentage of polymorphic bands for each primer in this experiment was 98.98%, and the highest polymorphic information content (PIC) was associated with ISSR 16, which had a value of 0.35. The findings highlight the efficiency of ISSR markers in distinguishing thorny and thornless blackberry genotypes at the main genotype groups: the first linked to initial thornless generations of Rubus laciniatus, and the second comprising crosses related to the Merton cultivar. Overall, significant genetic diversity among blackberry cultivars suggests valuable applications in breeding and improvement programs.