Identification of DNA markers linked to partial resistance for blast disease in rice across four locations

One hundred and fourteen doubled haploid plants of IR64/Azucena population were used to identify QTL controlling partial resistance to rice blast disease. The plants were scored for leaf and neck blast reaction in three locations in South India and at IRRI (Philippines). Seedlings were evaluated in nursery for leaf blast and in field for neck blast reaction. The RFLP marker data consisting of 175 DNA markers was used for mapping of QTL (MAPMAKE/QTL, LOD>2.50). Among the several QTL were identified, the major QTL flanked by RG958-RZ816 on chromosome 12 was common in two locations, IRRI, Philippines and Ponnampet, India with a range LOD score of 2.44-8.87, and 10.8% - 27.4% variation. Another QTL on chromosome 5 linked to RZ649-RZ225 markers was identified for leaf blast resistance in Ponnampet location (LOD=2.67, 16.5% variation) and for neck blast resistance in Mudigere location in India (LOD=2.42, 11.1% variation). A major QTL on chromosome 9 linked to Amy3ABC-RG667 markers was identified for neck blast resistance in Bangalore (LOD=2.03, 8.5% variation). The occurence of common QTL could be due to pleiotropic effect of QTL. The tightly linked markers will be fine mapped and used in MAS and in developing isogenic lines.