QTL x N-level interaction for plant height in rice (Oriza Sativa L.)

Quantitative trait loci (QTLs) for plant height in rice were mapped onto the molecular marker linkage map of a double-haploid (DH) population derived from a cross between IR64 and Azucena under low and high N levels, in both nutrient solution and soil culture experiments. Two QTLs, one on chromosome 1 and the other on chromosome 8, were detected at high N levels in soil and/or nutrient solution culture experiments. A total of 8 QTLs were identified at low N level in the soil and/or nutrient solution culture experiments, which located on chromosomes 1, 2, 3, 4, 5 and 6, respectively. The QTL flanked by the molecular markers RZ730 similar to RZ801 on chromosome 1 was identified in all experimental conditions. This position corresponds to sd-1, a semi-dwarfing gene. The QTLs on chromosomes 2, 3, 4, 5 and 6 were only detected at low N level and the QTL on chromosome 8 was only detected at high N level in the nutrient solution culture experiment. Based on the differing responses to low N stress between two parents and the QTLxN-level interaction observed in this study, it is suggested that the expression of several QTLs associated with plant height could be induced by low N stress.