离子束诱变水稻多胚苗突变株的筛选及其多胚来源

以低能氮离子束为诱变源， 通过对同源四倍体水稻品系“IR36 4X”进行离子注入后在其第2代群体内筛选得到了1株具有多胚苗性状特征的突变株（IR36 双）， 对该突变株后代的多胚苗形态特征及其多胚来源进行了研究。 结果表明， 多胚苗突变株系“IR36 双”在双胚苗性状的表现形态上有其特异性， 在同一纯合株系的群体内双胚苗的苗位有非完全双苗和完全双苗两种类型。 非完全双苗包括单胚轴单胚根双苗和单胚根异胚轴双苗这两种类型； 完全双苗也可以进一步划分为正常双苗和异常双苗两种类型。 在多胚苗材料中， 单胚根单胚轴双苗所占的比例相对较大。 其多胚（额外胚）的来源主要有4种可能性， 即双套胚囊形成多胚、 多卵卵器形成多胚、 反足细胞团发育形成不定胚及胚乳细胞形成不定胚（胚乳细胞胚状体）。 由此可见， “IR36 双”植株表现双胚苗性状有其胚胎学根源。

Screen of Polyembryonic Mutant Rice Induced by Ion Beam Implantation and Initiation of Its Additional Embryo

In the present study, the autotetraploid rice IR36-4X was treated with ion implantation technique by nitrogen ion beams and a polyembryonic seedling mutant(named as the IR36-Shuang) was identified in M2 generation. The mutant line was systematically investigated about the location of seedling in polyembryonic seedling, and the cytological initiation of the additional embryo in the IR36-Shuang was observed and determined. The results are as follows: The location of seedling in the polyembryonic rice IR36-Shuang could be differentiated into 2 types: the uncomplete twin seedlings and the complete twin seedlings. There were 2 types in the uncomplete twin seedlings, i.e. the twin seedlings with single plumule axis and single radicle and the twin seedlings with single radicle and twin plumule axis. The complete twin seedlings also included 2 types, i.e. the normal twin seedlings and the abnormal twin seedlings. The double-embryo was observed during different embryo development stage of the IR36-Shuang. The additional embryo in the IR36-Shuang might arise from the double set of embryo sacs in single ovary, multi-egg-cell egg apparatus, antipodal cells or endosperm cells. The results revealed the practicability of ion beam implantation technique in creating new polyploidy idioplasm, which could provide a new approach for searching the material with apomixis.