Abstract
Rice plants mainly utilize an NH4+ as a major nitrogen source at the natural habitat. Toward identification of regulatory genes involved in NH4+ uptake and assimilation, backcross inbred lines between Nipponbare (japonica rice) and Kasalath (an indica rice) were employed to detect quantitative trait loci (QTLs) for plant growth under various concentration of NH4+. Germinated seedlings were grown in water alone till the endosperm had been thoroughly utilized. Then the seedlings were hydroponically grown in a green house supplied with 0.005, 0.05, 1, 25 or 40 mM NH4+ for a week. A total of 31 QTLs were detected for differences between pre- and post-NH4+ treatment in length and dry weight of both shoot and root. Most of these QTLs were distinctly detected at low or high NH4+ application. These data suggest that individual gene plays an important role to support plant growth in a specific range of NH4+ concentration.
