水稻纯合胚致死突变研究

Homologous Embryo Lethal Mutant in Rice

以ＥＭＳ的处理并结合组织培养技术成功地获得胚致死突变的纯合再生植株。该植株生长发育正常，除种子无发芽能力外，纯合突变体的一切性状均与亲本品种表现一致。观察到胚败育的各种表现：（１）仅具有一个球形胚。（２）完全没有胚器的分化。（３）仅具胚根的分化而无胚芽的分化。（４）胚芽分化不完全。（５）胚芽与胚根之间没有输导组织相连接或者输导组织发育不完全等等。（纯合突变体×正常品种）杂种当代的种子（Ｆ１）发芽正常，而由Ｆ１及Ｒ１植株上所产生的种子（Ｆ２及Ｒ２）约有３／４具发芽能力，而１／４无发芽能力。统计分析的结果表明胚致死突变受隐性单基因控制。据我们所知，获得胚致死突变纯合体的成熟植株，本研究乃是首例报告，至少在水稻上是如此。在以利用无融合生殖之固定杂种优势的“一系法”杂交水稻生产的设想中，胚致死突变可作为胚乳的提供者而加以利用。

y using suspension culture,in which the liquid medium contained the chemical mutagen ethyl methanesulfonate (EMS),four embryo-lethal mutants in indica rice were obtainedIn the R2 generation,homozygous embryo-lethal mutants were segregated and their seeds lost the ability for germinationThe calli were induced from the seeds of the mutant on MS medium with 2,4-D,and subsequently plantlets of the homozygous embryo-lethal (HEL) mutant were successfully regeneratedThese homozygous mutants grown up to mature stage and set seeds,except that their seeds did not germinateAll characters of the homozygous mutants were normal as wild typeAs we know,this is the first sample of embryo-lethal mutant which in homozygous state could grow up to mature stage at least in riceSeed germination in hybrid F1 (HEL mutant/normal rice) was normal and in hybrid F2 or R2,the segregation ratios in seed germination were in accord with 3 germination:1 non-germination,showing that the mutants were controlled by single recessive geneHistological and cytological studies revealed that the stages of embryo degeneration in different mutants were variousIn mutant EL 44-1 embryo degeneration at globular stage and double embryos in a embryo sac were observedIn mutant EL 44-2,the embryos only possessed ill-developed coleoptile,no in mutant 961,the matue embryos possessed root and coleorhiza only and showed no coleoptile and shootIn other cases,coleoptile developed well but no shoot differentiatedIn mutant EL 144,the embryos developed into mature stage,with shoot poorly differentiatedIn some cases,the embryo developed well in structure,vascular bundles or with ill-developed ones with out between their shoot and rootThe authors suggest that the mutants might be useful in hybrid rice production by one line method (fixing the heterosis) based on apomixis in the futureIn this system,the homozygous embryo-lethal mutants could provide endosperm to the apomictic embryo which might be produced from hetorozygous somatic tiesues of the hybrid rice