MAPPING OF BLAST RESISTANCE GENE(S) FROM A DOUBLED HAPLOID DERIVATIVE OF RICE GENOTYPE ‘TETEP
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Date
2017-07
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CSKHPKV, Palampur
Abstract
Genetic analysis of an F2 population of cross HPU741 x TDH251 indicated that the blast resistance in TDH251 was controlled by a single dominant gene tentatively designated as Pi-67(t). Based on the linkage analysis of an F2 population of cross HPU741 x TDH251, the resistance gene was fine mapped to a 0.4 cM interval flanked by marker YL87/155 on the telomeric side and RRS8 on the centromeric side on the short arm of chromosome 12. By projecting the sequences of flanking markers on the reference sequence of cv. Nipponbare, a 2.03 Mb region extending from position 10608763 to 12630735 b near the centromere of rice chromosome 12 was delineated as the region of blast resistance locus. The Pi-67(t) gene is inferred to be embedded in a highly recombination suppressed region as the physical/genetic (P/G) distance ratio in the interval defined by markers YL87/155 and RRS8 is 5025kb/cM, which is nearly 20 times higher than the average P/G ratio of 260-280 Kb/cM estimated in rice. A total of 106 predicted genes were identified in Pi-67(t) region by surveying the equivalent genomic region of cv. Nipponbare in Rice Annotation Project database (RAP-db) (http://rapdbbeta.dna.affrc.go.jp). Out of these, Os12g0281600 encoding Nucleotide-binding site and leucine-rich repeat (NBS-LRR) protein was short listed as a potential candidate for the blast resistance gene identified from TDH251. The Pi-67(t) linked markers identified during this study can be exploited in marker-assisted breeding programmes for its speedy and precise mobilization into blast susceptible varieties. The physical localization of Pi-67(t) and identification of a NBS-LRR gene Os12g0281600 as a potential R-gene candidate has set the stage for cloning and functional characterization of this resistance gene.
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