Linkage analysis and characterization of QTL on chromosome 8 controlling nitrogen utilization under low NH₄⁺ condition in rice (Oryza sative L.)

Abstract

Nitrogen utilization of rice is determined by several factors, such as uptake, assimilation and other various steps. Morphology of rice root dramatically changes according to the supply of different ammonium concentration. Chromosome segment substitution lines (CSSLs) developed between Koshihikari and Kasalath were employed for mapping QTLs controlling root length. A QTL stimulating root length under low NH₄⁺ condition was detected on chromosome 8. A CSSL, SL-225, which has a Kasalath segment on a long arm of chromosome 8, and Koshihikari were hydroponically grown under various concentration of NH₄⁺ (5-500 μM). Root length of the SL-225 was significantly longer than Koshihikari under all concentration tested, and the elongated root reduced the uptake of NH₄⁺ at 50 μM NH₄⁺. Backcrossed progenies derived from SL-225 were used for the high resolution linkage analysis. The QTL was narrowed down at approximately 40 kb-region on chromosome 8.