Genetic diversity analysis of gamma irradiated mutant lines of banana (Musa X paradisiaca L.) cv. lakatan using microsatellite markers

Twenty three microsatellite markers were used to determine the variation at DNA level in 92 gamma irradiated Lakatan plants. Seven out of 23 primers revealed genetic variation both within and among groups of the irradiated mutant lines. The irradiated plants which were grouped according to gamma dosage namely, population A (5 Gy), population B (20 Gy), population C (25 Gy) and population D (30 Gy), were compared with the non irradiated or the Control. The allele distribution, pattern and frequency of the four populations of the irradiated plants differed with the Control. Population A generated alleles ranging from 0 to 3 with the highest average number of alleles at 1.94 in marker mMaCIR25. Population C had the least number of alleles at 1.10 while population D and B had 1.58 and 1.88. The other six polymorphic markers also amplified varying number of alleles. The highest PIC [polymorphism information content] value (0.85) was noted for mMaCIR25 which made it appropriate to be used as a marker in banana diversity analysis. The said primer having the highest PIC values across populations can efficiently discriminate variation in irradiated lines. Similarly, high PIC values of 0.82, 0.71 and 0.82 were noted for mMaSTMS15, pMaCIR348b and pMaCIR108, respectively. PIC value of 0.52 was noted for mMa1-6 while 0.58 was calculated for pMaCIR1113. The primer pMaCIR332a had the lowest PIC value of 0.46. Percent similarity was determined to evaluate allele diversity among populations. The highest percent similarity was between populations B and C at 78.5% while the lowest were populations A and D at 56.8%. UPGMA-SAHN cluster analysis generated nine clusters forming three clusters from Population A, one cluster for B, two clusters from C and two clusters for D. The Control was a separate cluster apart from gamma irradiated lines. The variability was likewise manifested in the agronomic traits as well as the disease reactions of the mutant lines.