Sais-Beul Lee1, Yeon-Jae Hur1, Jun-Hyeon Cho1, Jong-Hee Lee1, Tae-Heon Kim1, Soo-Min Cho1, You-Chun Song1,Young-Su Seo2, Jungkwan Lee3, Tae-sung Kim4, Yong-Jin Park5, Myung-Kyu Oh1 and Dong-Soo Park1*
1National Institute of Crop Science, Milyang, Miryang 50424, Republic of Korea. 2Department of Microbiology, Pusan National University, Pusan 46241, Republic of Korea. 3Department of Applied Biology, Dong-A University, Pusan 49135, Republic of Korea. 4Department of Agriculture, Korea National Open University, Seoul 03087, Republic of Korea. 5Department of Plant Resources, Kongju National University, Yesan 32439, Republic of Korea.
* Correspondence: Dong-Soo Park
Abstract
Background
Bakanae or foot rot disease is a prominent disease of rice caused by Gibberella fujikuroi. This disease may infect rice plants from the pre-emergence stage to the mature stage. In recent years, raising rice seedlings in seed boxes for mechanical transplanting has increased the incidence of many seedling diseases; only a few rice varieties have been reported to exhibit resistance to bakanae disease. In this study, we attempted to identify quantitative trait loci (QTLs) conferring bakanae disease resistance from the highly resistant japonica variety Wonseadaesoo.
Results
A primary QTL study using the genotypes/phenotypes of the recombinant inbred lines (RILs) indicated that the locus qBK1 WD conferring resistance to bakanae disease from Wonseadaesoo was located in a 1.59 Mb interval delimited on the physical map between chr01_13542347 (13.54 Mb) and chr01_15132528 (15.13 Mb). The log of odds (LOD) score of qBK1 WD was 8.29, accounting for 20.2% of the total phenotypic variation. We further identified a gene pyramiding effect of two QTLs, qBKWD and previously developed qBK1. The mean proportion of healthy plant for 31 F4 RILs that had no resistance genes was 35.3%, which was similar to that of the susceptible check variety Ilpum. The proportion of healthy plants for the lines with only qBKWD or qBK1 was 66.1% and 55.5%, respectively, which was significantly higher than that of the lines without resistance genes and that of Ilpum. The mean proportion of the healthy plant for 15 F4 RILs harboring both qBKWD and qBK1 was 80.2%, which was significantly higher than that of the lines with only qBKWD or qBK1.
Conclusion
Introducing qBKWD or pyramiding the QTLs qBKWD and qBK1 could provide effective tools for breeding rice with bakanae disease resistance. To our knowledge, this is the first report on a gene pyramiding effect that provides higher resistance against bakanae disease.
Keywords : Rice, Bakanae, Gibberella fujikuroi, QTL mapping, Resistance, Gene pyramiding