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Homologous Embryo Lethal Mutant in Rice

1997; Science Press; Linguagem: Inglês

0379-4172

Ling Ding-hou,

Plant Taxonomy and Phylogenetics

y using suspension culture,in which the liquid medium contained the chemical mutagen ethyl methanesulfonate (EMS),four embryo-lethal mutants in indica rice were obtainedIn the R2 generation,homozygous embryo-lethal mutants were segregated and their seeds lost the ability for germinationThe 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 regeneratedThese homozygous mutants grown up to mature stage and set seeds,except that their seeds did not germinateAll characters of the homozygous mutants were normal as wild typeAs we know,this is the first sample of embryo-lethal mutant which in homozygous state could grow up to mature stage at least in riceSeed germination in hybrid F1 (HEL mutant/normal rice) was normal and in hybrid F2 or R2,the segregation ratios in seed germination were in accord with 3 germination:1 non-germination,showing that the mutants were controlled by single recessive geneHistological and cytological studies revealed that the stages of embryo degeneration in different mutants were variousIn mutant EL 44-1 embryo degeneration at globular stage and double embryos in a embryo sac were observedIn 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 shootIn other cases,coleoptile developed well but no shoot differentiatedIn mutant EL 144,the embryos developed into mature stage,with shoot poorly differentiatedIn some cases,the embryo developed well in structure,vascular bundles or with ill-developed ones with out between their shoot and rootThe authors suggest that the mutants might be useful in hybrid rice production by one line method (fixing the heterosis) based on apomixis in the futureIn 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