Phenotypic And Moleculer Characterization Of Recombinant Inbred Groundnut Lines For Resistance To Groundnut Rosette Disease

ABSTRACT

Groundnut rosette disease is the most constraint to the production of groundnut causing annual economic loss of US $156 millions in sub-Saharan African countries. The present study evaluated 220 (F5) Recombinant inbred lines (RIL) derived from 12991 X ICGV 86124 resistant and susceptible parents respectively, for resistance to groundnut rosette disease so as to identify resistant Recombinant Inbred Lines (RIL) and markers linked to Groundnut Rosette Disease resistance. The RIL were planted at Sokoine University of Agriculture (SUA) and screening was done by inoculating mechanically all the RILs at seedling stage using rosette virus inoculum prepared from susceptible groundnut plants obtained at SUA. Scoring for rosette disease was done, using a scale of 1-5, 1 being highly resistant and 5 highly susceptible. Forty-two RILs were highly resistant, 109 RILs were moderately resistant while 60 RILs were classified as Susceptible. Chi-square test (X2 = 3.30, P≤ 0.25) for this phenotype demonstrated that the resistance was qualitatively controlled. DNA samples from 15 most resistant recombinant inbred lines were pooled to form resistant bulk while DNA samples from 15 most susceptible RILs were pooled to form susceptible bulk. Then the bulks along with the two parents were screened with 30 SSR primer pairs. A total of 10 markers amplified 63 alleles of which 59 alleles were polymorphic while four alleles were monomorphic. The number of alleles per marker ranged from four to eight with the average of six alleles. Five SSR Markers, tc7a02180, pm 36290, tc7h11400, tc9f04295 and t11a02280 amplified DNA fragments in only resistant parent and some of the resistant bulks and produced no amplification in susceptible parent and some of the susceptible bulks. The Polymorphic Information content (PIC) values ranged from 0.32 to 0.52. The identified marker can be used during selection of resistance to rosette disease plants/progenies.