Abstract: A semidwarfing rice mutant hya1，  genetically  unstable  in plant height was obtained through  space mutagenesis of Texianzhan 13. Compared to the wild type, hya1 mutant was featured by  semidwarfness,   fewer  tillers, slim culms, reduced grain number  per panicle, low seed setting rate and low germination rate. Segregation of plant height in  selfed progenies of the mutant  was observed. Normal plants of selfed progenies, however, showed genetic stability. Plant height of F1 hybrid and F2 progenies generated from the cross  between hya1 mutant and Texianzhan 13 did not follow Mendelian inheritance. Furthermore, selfedprogenies of the  mutant  had  abnormal chromosome numbers (e.g. 2n=22, 23, 25 and 36 instead of 2n= 24). In addition, there were some pollen mother cells of hya1  with 11 bivalents at the diakinesis stage of meiosis. Realtime quantitative PCR analysis of normal and semidwarf plants from selfed progenies of  the mutant along with Texianzhan 13 showed equal copy number of chromosome in normal and wild type plants while the copy number of chromosome 8 and 11   differed in hya1and semidwarf plants from the selfed progenies. It    suggested  that hya1 mutant is a new aneuploid in which abnormal phenotype and genetic instability are caused by  abnormal chromosome number and/or varying copy number of certain chromosomes.

Key words: rice, hya1mutant, aneuploid, semidwarf

摘要： 通过空间诱变得到半矮秆突变体hya1，该突变体半矮秆性状遗传稳定性丧失。与其野生型特籼占13相比，hya1株高显著降低、分蘖少、茎秆细弱、每穗粒数减少、结实率降低、发芽率降低。单株收获半矮株hya1自交种子，对半矮生性状进行连续选择，发现该性状无法纯合稳定，自交群体株高长期分离（半矮秆和野生型）；分离群体中的野生型个体自交，其株高性状稳定。利用hya1与特籼占13配制杂交组合，其F1及F2株高表型不符合孟德尔分离规律。hya1自交收获种子根尖细胞染色体数目出现了2n=22、23、24、25、36的变异，且在减数分裂终变期发现了二价体数目为11的异常花粉母细胞。荧光定量结果表明， hya1自交后代野生型个体12条染色体的基因拷贝数与对照接近，而半矮秆个体在第8和第11染色体上的基因拷贝数与对照存在显著差异。综合以上结果，推断hya1为水稻新型非整倍体材料，其染色体数目异常导致表型异常和遗传不稳定性，对其深入研究有助于了解水稻减数分裂分子调控机理。

关键词: 水稻, hya1突变体, 非整倍体, 半矮秆