Abstract
BackgroundBakanae disease is an important fungal disease caused by Gibberella fujikuroi. Incidence of rice bakanae disease creates serious problems in the foremost rice growing countries, and no rice variety has been found to be completely resistant to this disease. However, breeding rice varieties resistant to bakanae disease may be a cost-saving solution preferable to the application of fungicides. In this study, we aimed to determine the exact position and the candidate gene for qBK1, a major resistant quantitative trait locus (QTLs) for bakanae disease.ResultsThe genotypes/phenotypes of recombinants selected from backcrossed recombinant inbred lines of two rice varieties, Shingwang (resistant) and Ilpum (susceptible), indicated that the locus qBK1, conferring resistance to bakanae disease in Shingwang, was delimited to a 35-kb interval delimited by InDel 18 (23.637 Mbp) and InDel 19–14 (23.672 Mbp). Sequence analysis of this 35-kb region revealed four candidate genes, LOC_Os01g41770, LOC_Os01g41780, LOC_Os01g41790, and LOC_Os01g41800. There were many non-synonymous SNPs in LOC_Os01g41770 and the transcript of LOC_Os01g41790 was early terminated in Shingwang, whereas there were no differences in both LOC_Os01g41780 and LOC_Os01g41800 sequences between Ilpum and Shingwang. Expression profiling of the four candidate genes showed the up-regulation of LOC_Os01g41770, LOC_Os01g41780, and LOC_Os01g41790 in Ilpum and of LOC_Os01g41800 in Shingwang after inoculation of G. fujikuroi.ConclusionUtilization of marker-assisted selection (MAS) with a precise molecular marker on qBK1 could provide an effective tool for breeding rice varieties resistant to bakanae disease. To our knowledge, this is the first report on fine mapping and candidate gene approaches for identifying the gene for qBK1.
Highlights
Bakanae disease is an important fungal disease caused by Gibberella fujikuroi
In our previous study (Hur et al 2015), we identified a major quantitative trait locus (QTLs), qBK1, from the Korean indica variety Shingwang. qBK1 is located within a 520-kb region of chromosome 1 between the simple sequence repeat (SSR) markers RM8144 (23.20 Mb) and RM11295 (23.72 Mb) with RM9 (23.32 Mb) as the peak marker
Fine mapping of qBK1 We previously identified qBK1 in the 520 kb region between RM8144 and RM 11295 on chromosome 1 (Hur et al 2015)
Summary
Bakanae disease is an important fungal disease caused by Gibberella fujikuroi. Incidence of rice bakanae disease creates serious problems in the foremost rice growing countries, and no rice variety has been found to be completely resistant to this disease. Bakanae disease (from the Japanese “foolish seedling”), caused by the fungus Gibberella fujikuroi, was first described in 1828 in Japan (Ito and Kimura 1931). It is one of the most serious and widespread problems of rice growing countries in Asia and Africa, and in North America and Italy (Ou 1985; Pra et al 2010). The typical symptoms are abnormal elongation, including tall, lanky tillers, pale green flag leaves, dried-up leaves, and infertile panicles (Ou 1985; Mew and Gonzales 2002) Seeds contaminated with this fungus provide initial foci for secondary infection. The cultivation of resistant varieties would be a more economic and effective way to control this disease
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