QTL analysis of the qBK1, a major QTL for bakanae disease resistance in rice

Bakanae disease is one of the most serious and oldest problems of rice production, which was first described in 1828 in Japan (Ito and Kimura 1931). This disease may infect rice plants from the pre-emergence stage to the mature stage, with severe infection of rice seeds resulting poor germination or withering (Iqbal et al. 2011). Under favorable environmental conditions, infected plants have the capacity to produce numerous conidia that subsequently infect proximate healthy plants, resulting in major yield loss (Ou 1985). One hundred sixty nine NILs, YR28297 (BC6F4) generated by five backcrosses of Shingwang with the genetic background of susceptible japonica variety, Ilpum were used for QTL analysis. Rice bakanae disease pathogen, CF283, was mainly used in this study and inoculation and evaluation of bakanae disease was performed with the method of the large-scale screening method developed by Kim et al. (2014). A major QTL for resistance against bakanae disease on chromosome 1 was identified using SSR marker, RM9, which explaining 65 % of the total phenotype variation. The major QTL designated as qBK1 and mapped to a 4.4 Mbp region between RM24 (19.30 Mb) and RM11295 (23.72 Mb). The results of this study are expected to provide useful information toward developing resistant rice lines to this detrimental fungal disease.