New Endosperm Mutations Induced by Chemical Mutagens in Rice Oryza sativa L.

Abstract

Various kinds of mutations for endosperm or embryo character were induced in rice by treatment with three kinds of chemical mutagens, ethyl methanesulfonate (EMS), ethylene imine (EI) and N-methyl-N-nitrosourea (MNU). MNU induced few mutations in the treatment of dry seeds, but considerably more through the treatment of fertilized egg cells. The frequency of endosperm mutations was lower than that of chlorophyll mutations. The white core mutation was induced most frequently among mutations for endosperm or embryo character. Each of the mutants, except for floury mutant CM 2055, was controlled by a single recessive gene. Dull mutants were intermediate between waxy and non-waxy rice in the degrees of translucence and of staining by I-KI solution. The degrees of them were different among lines, although they were almost the same within a line. The phenotypic manifestations of white core and floury mutants were caused by the loose packing of round compound starch granules in their endosperm cells. From the analogy of grain features of rice with maize, the glassy and the floury types of wrinkled mutation were named as 'sugary' and 'shrunken', respectively. In addition to various endosperm mutations, a mutation for embryo character, 'giant embryo', was induced.