Fine Mapping Of A Novel Blast Resistance Gene Pimh(t) In An Elite Rice Restorer Line Minghui 63

Rice blast, caused by Magnaporthe grisea (Hebert) Barr, is one of the most serious and widespread diseases of rice worldwide. The exploitation and utilization of broad-spectrum or durable resistance genes is considered to be a very important and effective way for rice blast control.Minghui 63, a most famous hybrid rice restorer line, showed broad-spectrum resistance to rice blast in China. In this study, we conducted the genetic analysis and mapping of resistance genes in Minghui 63 for its blast resistance by inoculating F2 and F3 populations derived from a cross LTH x Minghui 63 with four differential isolates HD12,GDBR8,06/41/2 and 06N/10/2, which showed broad-spectrum virulence to 31 monogenic lines jointly developed by International Rice Research Institute (IRRI) and Japan. Some results obtained were as follows:1. The resistance of Minghui63 to isolates HD12 and GDBR8 could be controlled by one same dominant resistance gene, Pimh(t), and to isolates 06/41/2 and 06N/10/2 by two dominant resistance genes. Therefore, it could be concluded that the resistance donor Minghui 63 harbored at least two resistance genes effective to Magnaporthe grisea isolates.2. The Pimh(t) gene was mapped at the end of the long arm on chromosome 2, flanked by RM213 and RM3542 by using BSA-RCA (bulked-segregate analysis and recessive-class analysis) strategy and SSR markers. Due to its difference from the cloned Pib gene within the same chromosome interval, which confirmed by several kinds of experimental assay, such as blast inoculation, PCR amplification using Pib-specific primers, etc., we deduced that the gene Pimh(t) is a novel blast resistance gene.3. We further anchored the gene Pimh(t) within a 51kb interval, flanked by two markers AP91SR15 and AP20InDeL1 by exploiting new DNA markers. Based on the DNA sequence of Nipponbare, we predicted candidate genes of Pimh(t) by using several gene prediction programs.