Abstract:

【Objective】 To understand and provide a theoretical basis for the molecular mechanism of plant height in rice, QTLs controlling plant height and its component factors were detected and compared with the genes involved in gibberellin and brassinosteroid biosynthesis and transduction. 【Method】 The QTLs affecting plant height and its component factors were analyzed by employing 126 recombinant inbred lines (RILs) derived from a cross between two japonica rice cultivars, Shennong 265 and Lijiangxintuanheigu, and then compared them with the genes involved in gibberellin and brassinosteroid biosynthesis and transduction. 【Result】 Plant height and its component factors showed a continuous normal distribution in the RILs population. The plant height showed a high positive correlation with its component factors. The correlation between adjacent plant height components was positively significant while the significance of the correlation between non-adjacent plant height components was less or even negative. Further result indicated that the plant height was mainly affected by the length of I internode and IV internode from top. A total of 21 QTLs controlling plant height and its components were identified on chromosomes 1, 2, 3, 5, 6, 7, 8, 9, 11 and 12, respectively. QPH9b (EP1, DEP1 or qPE9-1) on chromosome 9 plays a very important role in affecting plant height through controlling the I internode and II internode length from top. Its molecular function was different from the other genes controlling plant height identified previously. So, it would provide a novel mechanism for plant height. 【Conclusion】 Comparison between 21 QTLs and genes controlling gibberellin and brassinosteroid biosynthesis and transduction indicated that the genetic basis of plant height is extremely complex in this RILs population.

Key words: japanica rice, plant height, internode length, quantitative trait locus, gibberellin, brassinosteroid