A mutant RM109 of rice (Oryza sativa L.) exhibiting altered lateral root initiation and gravitropism

摘要

Following treatment of seeds with NaN3, a large population of rice (Oryza sativa cv. Oochikara) M2 seedlings was screened to select mutants resistant to exogenously applied 2,4-D. A resistant line, RM109, was identified, and its resistance to 2,4-Dwas controlled by a dominant single gene. Its seedlings had altered lateral root production, root gravitropism and several root hairs, but no significant difference was observed between RM109 and the wild type in plant height, number of roots and seminalroot length. The pericycle cell number in the root of RM109 mutant was 70-80% of that of the wild type, indicating that the deficient lateral root production was mainly based on irregular cell division. No difference in number of amyloplasts was found between the two. However, amyloplast size in columella cells of RM109 root cap was 50-60% that of the wild type. This suggests that the root of the mutant was agravitropic.