Fine mapping of a strong QTL of field resistance against rice blast, Pikahei-1t, from upland rice Kahei, utilizing a novel resistance evaluation system in the greenhouseReportar como inadecuado




Fine mapping of a strong QTL of field resistance against rice blast, Pikahei-1t, from upland rice Kahei, utilizing a novel resistance evaluation system in the greenhouse - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Theoretical and Applied Genetics

, Volume 117, Issue 6, pp 997–1008

First Online: 29 August 2008Received: 25 January 2008Accepted: 21 June 2008

Abstract

Field resistances FR against rice blast are highly evaluated by breeders for their durability, in contrast to the conspicuous but often less durable true resistances. However, lack of efficient systems for evaluation of resistance has delayed their practical application. Kahei, an upland domestic cv., is known for its very high FR against rice blast. We fine-mapped its highest quantitative trait loci QTL, qBFR4-1, using residual heterozygosity of recombinant inbred lines RILs and our semi-natural rice blast inoculation-evaluation system in the greenhouse, with comparable accuracy to the true resistance genes. This system enabled reproducible high-density infection, and consequently allowed quantification of the resistance level in individual plants. The target region was first narrowed down to about 1 Mb around at 32 Mb from the top of chromosome 4 in the Nipponbare genome, with the upland evaluation system assessing the F7 generation of Koshihikari lowland, FR: very weak × Kahei upland, FR: very strong RILs. Then, F9 plants 4,404—siblings of hetero F8 plants at the region—were inoculated with rice blast in a greenhouse using the novel inoculation system, and individual resistance levels were diagnosed for fine QTL analysis and graphical genotyping. Thus, the resistance gene was fine-mapped within 300 kb at 31.2–31.5 Mb on chromosome 4, and designated Pikahei-1t. By annotation analysis, seven resistance gene analog RGA ORFs of nucleotide-binding-site and leucine-rich-repeat NBS-LRR-type were found in the center of the region as the most likely candidate counterparts of the resistance gene. This is similar in structure to the recently reported Pik cluster region, suggesting that most of the other dominant QTLs of the FRs may have similar RGA structures.

Communicated by Q. Zhang.

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Autor: Xin Xu - H. Chen - T. Fujimura - S. Kawasaki

Fuente: https://link.springer.com/



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