부산대학교 도서관

The root is the sole organ taking up water andnutrients from soils. Hence, root system architecture (RSA)is important for enhancing high-level and stable rice(Oryza sativa L.) production. However, the geneticimprovement of RSA has received less attention than yieldand yield components. Here, we aimed to identify andcharacterize quantitative trait loci (QTLs) for RSA bydetermining the maximum root length (MRL) of seedlingsgrown hydroponically under various concentrations ofNH4?. We used a total of 280 introgression lines (ILs) withan Indica-type variety IR64 genetic background, consistingof ten sibling ILs groups, to detect the QTLs. Greatervariation of MRL was found in three sibling ILs groups. Intotal, five QTLs were detected by single marker analyses:two each on chromosomes 5 and 6 and one on chromosome7. Among them, the most effective QTL was detected on asegment derived from IR69093-41-2-3-2 (YP5), which waslocalized to the long-arm of chromosome 6. The QTL,designated as qRL6.4-YP5, concerned in root elongation. MRL and total root length of a near-isogenic line (NIL) forqRL6.4-YP5 were significantly (15.2–24.6 %) higher thanthose of IR64 over a wide range of NH4? concentrations. Root number and weight of the NIL were the same as thoseof IR64. These results indicated that qRL6.4-YP5 was aconstitutive QTL for root length in response to change innitrogen concentrations. To enhance yield potential byimproving RSA, qRL6.4-YP5 might help to improve rootdevelopment in rice molecular breeding programs withmarker-assisted selection.