水稻半矮秆基因iga-1的鉴定及精细定位

在前期通过空间诱变获得半矮秆隐性突变基因iga-1的基础上，进一步对iga-1进行鉴定。农艺性状调查表明携带iga-1的矮秆株系CHA-2、CHA-2N与原种特籼占13相比存在明显变异。节间长度测量显示CHA-2、CHA-2N节间比例正常，属dn型。外源GA₃处理、内源GA₃测定和α-淀粉酶活性检测揭示iga-1与GA₃调控无关。利用CHA-2与粳稻品种02428杂交获得的F₂群体将iga-1定位在水稻第5染色体两个InDel标记DL18和DL19间32.01 kb的物理距离内。该区域有5个阅读框架，其中包括赤霉素信号传导调控基因D1。序列分析表明CHA-2、CHA-2N和特籼占13在D1位点上基因组序列不存在差异，推测D1并非iga-1的候选基因。比较水稻第5染色体上其他矮秆基因发现iga-1可能与半矮秆基因sd-7来自同一位点。

Identification and Fine Mapping of a Semidwarf Gene iga-1 in Rice

A semidwarf gene iga-1 of rice (Oryza sativa L.) by mutagenesis of outer space treatment from Texianzhan 13 was identified. The dwarf lines CHA-2 and CHA-2N which carried iga-1 showed great variation in agronomic traits. On the basis of the internode length of CHA-2 and CHA-2N, the mutant belongs to the dn type of dwarfing. GA₃ treatment, endo-GA₃ measurement and α-amylase activity analysis in endosperm showed that iga-1 is independent of gibberellin acid. Using a large F₂ population derived from a cross between the CHA-2 and an japonica rice variety, 02428, the iga-1 gene was fine mapped into a 32.01 kb physical distance between two InDel markers, DL18 and DL19 on chromosome 5, where five open reading frames were predicted, one of which was the rice gibberellin-insensitive dwarf mutant gene D1. Sequence analysis showed that no variation in D1 locus was detected among CHA-2, CHA-2N and Texianzhan 13. Thus, D1 can not be the candidate gene of iga-1. Comparing the other dwarf genes on chromosome 5 showed that iga-1 is possibly allelic to the semidwarf gene sd-7.