MOLECULAR DIVERSITY IN SELECTED LANDRACES RESISTANCE TO BLAST PATHOGEN (PYRICULARIA GRISEA COOKE EX SACC.) OF PEARL MILLET (PENNISETUM GLAUCUM (L.) R. BR.) GERMPLASM FROM NORTHERN NIGERIA

Abstract

Germplasm collection and sourcing for resistant genotypes among the available landraces through characterization and quantification of genetic diversity is essential for introgression in plant breeding programs. Therefore, study on molecular diversity of pearl millet (Pennisetum glaucum) landraces was carried out to characterize the crop accessions for resistance to blast pathogen as well as identify elite accession(s) for the crop improvement. Thirty five (35) pearl millet germplasm were collected from the major cultivated states in Nigeria and were screened for blast resistant genotypes on the field using a Randomized Complete Block Design (RCBD). Selected potentially resistant accessions for blast resistant were further confirmed under screen house condition and evaluated for genetic diversity using random amplified polymorphic DNA-PCR. Out of the 35 accessions screened for blast, 14 were potentially resistant to blast disease (with disease score of  3.9 on 1-9 scale). Further nursery screening of the potentially resistant accessions to blast showed that NS-YEL-02 was the most highly resistant followed by NG-ZB-01 with severity disease score of 0.00 and 0.33, respectively. Molecular diversity of selected 14 resistant and 2 susceptible accessions using random amplified polymorphic DNA showed no specific marker for resistant and susceptible accession to the disease. A total of fifty nine (59) amplified fragment bands with 10 DNA primers was generated, of which 53 (89.83%) were polymorphic and 6 (10.17%) were monomorphic. Genetic similarity among the accessions varied from 0.18 to 1.44 with an average gene diversity value of 0.74. Clustered dendrogram of the 16 accessions revealed two major cluster groups; two susceptible (KD-CK-01 and NGB501) accessions with similarity coefficient 1.14, and 14 resistant accessions. Clustering of the selected landraces base on resistance and susceptibility by RAPD techniques, indicate its possibility for indirect selection of blast resistant genotypes for the crop. The high resistance and clustering of NS-YEL-02 singly in a group by the makers indicate the uniqueness and its prospect for selection, as elite parent accessions in blast disease resistance breeding programs of pearl millet.