Molecular genetic analysis of a Tos17-tagged mutant line related to root morphology in rice [Oryza sativa]
2005
Iwao Mushika, J.(Kagawa Univ., Miki (Japan). Faculty of Agriculture) | Yuo, T. | Taketa, S. | Miyao, A. | Hirochika, H. | Ichii, M.
Although plant roots are one of the most important organs for crop cultivation, root studies lag behind due to various difficulties. The objective of the present study was to isolate genes related to root morphology using 'mutant panel', rice retrotransposon Tos l7-insertion mutant lines. First, we grew 5,568 R1 lines regenerated from tissue culture of Oryza sativa L. cv. Nipponbare in water culture, and screened the lines which segregated root mutants at the seedling stage. Then, 56 root mutant lines that were confirmed by the progeny test, were analyzed by genomic Southern hybridization using Tos 17 as a probe. As a result of linkage analysis, we obtained one Tos 17-tagged mutant line, NC6949. The phenotype of this mutant line was as follows: dwarf, narrow leaves and reduced numbers of crown roots and lateral roots. In this line, Tos 17 was inserted in the third exon of the putative alliinase gene on the short arm of chromosome l and the presence of this insertion cosegregated with the mutant phenotype. We designated the gene tagged by Tos l7, as OSAlll (Qlyza sativa alliinase 1). In a complementary experiment in which a 6 kb genomic fragment containing alliinase/ORFs and its putative promoter region was introduced into the osalll mutant, the root morphology in the transgenic plant was rescued. Based on these observations, it was concluded that the abnormal root morphology of the osalll mutant obtained in this study was caused by knock out of the OsAlll gene. In the rice genome, at least 3 other alliinase-1ike gene sequences are present and form a multigene family, but their expression patterns were different suggesting that OsAlll was functionally differentiated from the others.
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