Characterization of the QTL linked to tungro and green leafhopper resistance in rice (Oryza sativa L.) using advance backcross population
2016
Waing, F.P. | Pocsedio, A.E. | Fernando, T.C. | Alberto, R. T. | Waing, K.G.D. | Romero, G.O. | Tabanao, D.A.
Resistance to rice tungro virus (RTSV) and green leafhopper (GLH) found in the Indian landrace, ARC 11554, was previously localized on the short arm of rice chromosome 4 flanked by markers RM8213 and RM3471. This study aimed to infer the haplotype of the introgression region in backcross lines, determine the backcross line containing the resistance region that is most suitable for developing a mapping population, and narrow down the region of the putative chromosomal position of the resistance QTL using tightly linked molecular markers in an F2 mapping population. Fifty-five backcross line (11 BC sub 2 F sub 6 and 44 BC sub 4 F sub 4) in NSIC Rc138 backgrounds were used for haplotype characterization. Of the 55 lines, 22 backcross lines that resembled the donor region in chromosome 4 were selected for marker similarity analysis. Marker similarity ranged 81-96% among the BC sub 2 F sub 6 and 89-99% among BC sub 4 F sub 4 lines. Mapping population composed of 1,014 BC sub 5 F sub 2 were established from the cross between NSIC Rc138 and ARC138-4-5-5-2-30. The BC5 F2:3 lines were screened for tungro and GLH resistance. QTL detected for RTSV resistance accounted for 17.43% of the total phenotypic variance explained (PVE) and the GLH resistance QTL had a PVE of 19.19%. Two peaks were observed: one on the left side of RM8213 (RM335-RM16428) and a secondary peak on the right (RM16434-RM16497). The primary signal (peak LOD) was located in the RM16425-RM16427 region, the size of which is only 0.5 kb. This confirmed that the very strong resistance of ARC11554 is due to cosegregation of resistance genes conferring resistance to RTSV and GLH.
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