Abstract:

The recombinant inbred line (RIL) populations derived from Zhenshan 97B/Miyang 46（ZS97B/MY46） and their genetic linkage maps were employed to map QTLs controlling tolerance to high Al³⁺ stress by using paper culture of rice seedlings with two concentrations of Al³⁺ stress (20 mg/L and 30 mg/L). After 20 days of treatment, the relative root length (%) and relative seedling height (%) were measured as index for tolerance to high Al³⁺ stress. The results showed that two QTLs with main effects were detected based on relative root length, i.e. qRAC(r)2 and qRAC(r)11. The former detected in both treatments explained 12.92% and 16.15% of the total phenotypic variation. The positive additive effects came from the female parent, Zhengshan 97B, showing high potential tolerance to high Al³⁺ stress. Two main effect QTLs were also detected on chromosome 11 by relative seedling height, i.e. qRAC(s)11-2(20 mg/L Al³⁺) and qRAC(s)11-1 (30 mg/L Al³⁺). Epistasis analysis showed that the variation explained by epistasis QTLs was higher than that explained by the main effect QTLs, indicating that the QTLs displayed their effects through different ways of interaction. Based on relative root length, a total of eight pairs of epistasis including 15 QTLs were detected on six chromosomes (chromosome 1, 2, 3, 5, 6 and 10). Based on relative seedling height, a total of six pairs of epistasis were detected on 9 chromosomes (chromosome 1, 2, 3, 5, 6, 7, 8, 9 and 12). All the epistasis QTLs were not located at same loci where the main effect QTLs resided.

Key words: Rice, RIL population, QTLs mapping, Main effect, Epistasis effects, Tolerance to high Al³⁺ stress