Identification of a new resistance gene Pi-Da(t) from Dacca6 against rice blast fungus (Magnaporthe oryzae) in Jin23B background

摘要

Rice blast, caused by the fungal pathogen Magnaporthe oryzae, severely threatens rice production worldwide. A new resistance gene, Pi-Da(t), was found in Dacca6, a local upland rice variety from the Philippines. It was mapped into a region between RM5529 and RM211 on chromosome 2, where no blast resistance gene has been reported, by bulk segregant analysis (BSA) in a BC1F2 population from a cross between Dacca6 and Jin23B. The presence of Pi-Da(t) in Jin23B background, an elite parental line preferred for its good grain quality and widely adopted in China's three-line hybrid rice breeding program over the past 20 years, was verified by BSA and graphical genotyping with additional eight BC1F2 bulks. This work presents an example of combining gene mapping work and gene introgression with BSA and graphical genotyping methods in a backcross (BC) breeding scheme. Both the resistant Jin23B line and the linked markers will provide useful information and materials for marker-assisted breeding against blast disease in rice.