Genetic diversity and population structure study of drumstick (Moringa oleifera Lam.) using morphological and SSR markers

Genetic diversity assessment is prerequisite for future crop improvement programme therefore in the present study, morphological and molecular diversity among the 12 Indian drumstick (Moringa oleifera Lam.) populations were assessed. A total of 300 genotypes belonging to 12 populations of drumstick (M. oleifera Lam.) were collected from northern (Himachal Pradesh) and southern (Tamil Nadu) parts of India. Under field condition 14 qualitative and 11 quantitative morphological characters were recorded to assess the diversity at morphological level. Correlation studies showed significant correlation between the quantitative characters. At molecular level, 19 SSR primers that produced clear and reproducible bands were selected for diversity study. A total of 35 bands were amplified of which 29 (82.86%) were polymorphic with an average of 1.84 bands per primer. Polymorphic information content (PIC) value for SSR primers ranged from 0.01 for primer MO64 to 0.37 for primer MO1 with an average of 0.15. The gene diversity ranged from 0.01 to 0.49 with an average of 0.18. Cluster analysis based on morphological characters (qualitative and quantitative) divided populations into two groups whereas; SSR makers divided it into three groups. Population MO9 (PKM1) form Periyakulum, Tamil Nadu was ungrouped based on quantitative characters. Principal coordinate analysis (PCoA) with SSR markers showed that large diversity existed in Indian drumsticks collection. The percentage of variation explained by the first 3 axes was 31.69% (axis1 - 14.35%, axis2 - 9.39% and axis3 - 7.95%). Analysis of molecular variance (AMOVA) indicated that 2% diversity was attributed to differences among regions, 3% at the level of populations and 95% contributed by the genotypes within the populations. Model based population structure were tested using K values from 1 to 20, but there was no clear population structure, therefore Ln(PD) derived Δk was plotted against the K to determine the number of populations. Based on population structure analysis five clear populations were obtained instead of 12 natural populations. Cluster analysis and structure based population study showed that, no geographical isolation exists between genotypes collected from northern and southern part of India. Principal coordinate analysis showed large genetic diversity exists in Indian drumstick collection which can be utilised for crop improvement programme particularly traits related to oil yield.