Characterization of citrus germplasm using simple sequence repeat (SSR) markers

Abstract

In the present study, 25 simple sequence repeat markers were used to detect molecular polymorphism among 30 citrus genotypes representing seedling selections, clonal selections, exotic and indigenous species. A total of 87 alleles were detected and the banding pattern resolved by each primer pair was in accordance with single locus variation. Out of 25 primer pairs, 20 were found polymorphic and produced alleles ranging between 2 to 6 with an average value of 3.95. The polymorphism information content ranged from 0.16 for DY263095 to 0.39 for DY289396. Out of 20 SSR markers, 10 SSRs amplified specific alleles among eight genotypes. The genetic similarity coefficient for all accessions ranged from 0.11- 0.85%. Cluster analysis separated the genotypes into two groups at 0.11% similarities. The first major group comprised four species (G-26, G-27, G-29 and G-30). The 2nd major group consisted of 26 genotypes. Results confirmed that seedling origin pummelo (G-1 to G-5) are not true pummelo possibly because of their hybrid origin. However, seedless clone (G-18) and early bearing clone (G-20) of Nagpur mandarin showed similarity (78% and 69%, respectively) with Nagpur mandarin. The dwarf cluster bearing probable citrus hybrid exhibited affinity with sweet lime and constituted a group with 54% similarity.