STUDIES ON GENETIC REGULATIONS OF RICE INTERNODES FORMATION AND ELONGATION

水稻茎秆由一些伸长的节间组成，研究这些节间伸长的遗传规律对于水稻抗倒伏育种和株型改良具有重要意义。本项目试图检测和分离一些影响秆节间形成和伸长的矮秆或相关基因。本研究的主要结果如下：（1）筛选并检测了大量影响茎伸长和/或伸长节间分布格局的矮秆或相关突变体。（2）利用分子标记（d50、Ssi 1、ssi 2、d 61和d11）对部分突变体进行了表型分析和染色体定位。（3）利用分子克隆技术成功地分离到了dwatf（d1、d 6、d18、d 61和gid 1）和slr 1基因。（4）其中d 6为OSH 15基因的功能缺失突变（Oryza sativa homeobox 15），属于knotted 1-type homeobox基因家族的成员，其他的是与植物激素赤霉素的生物合成或信号转导相关的基因中的功能丧失突变（d1，d18，gid 1）或油菜素类固醇（d 61）等基因，对这些基因在茎节间形成和伸长中的功能和互作关系的研究正在进行中。

Rice culm is consisting of some elongated intemodes and to dear the genetic regulation of these intemodes elongation is important for breeding of lodging resistance and improvement of plant shape in rice cutivars. Then, in this project, we tried to detect and isolate some dwarf or related genes that affect culm internodes formation and elongation. Our research results are as follows :( 1 ) We screened and detected so many dwarf or related mutants affecting culm elongation and/or elongated internodes distribution patterns.( 2 ) We characterized phenotype of some mutants and mapped these mutant genes on the chromosome by useing some molecular markers (d50, Ssi1, ssi2, d61and d11).( 3 ) We succeeded to isolate some dwatf (d1, d6, d18, d61 and gid1) or slender (slr1) genes by molecular cloning.( 4 ) Among of them, d6 was identified as a loss-of-function mutation in OSH15(Oryza sativa homeobox15), a member of the knotted1-type homeobox gene family, and the others were as loss-of-function mutation in the genes related to biosynthesis or signal transduction of the plant hormones, gibberellin(d1, d18, gid1) or brassinosteroid (d61).Further studies on these genes function and interaction in the culm internodes formation and elongation ate in progress.