This study was performed to understand the divergence of catalase genes in the course of the evolution of higher plants. A comparison of exon-intron structures of plant catalase genes suggested that consecutive duplication of the primordial gene followed by differential loss of introns occurred to formthree diverse isozyme genes after the evolutionary divergence of monocots from dicots. In monocots, three ancestral isozyme genes were formed before the divergence of ancestral rice and maize. Intron-2 of the Oryza sativa CatAcatalase gene is similar in nucleotide sequence to p-SINE1, a retroposon, and seems to have been added to the ancestral genome of rice. Polymerase chain reaction (PCR) analyses of Oryza and related species revealed that all theOryza species with an AA genome have the CatA ortholog with the p-SINE1-likeintron, whereas other Oryza species have the CatA ortholog without the intron, and that the intron was already present in the common ancestor of Oryza and Leersia perrieri. Tourist-CatA, a transposable element in the 5\u27-flanking region of CatA and its orthologs, was found to be distributed in all fourOryza species complexes in the Oryzeae tribe. The AA genome Oryza species except for O. longistaminata contain the full-length Tourist-CatA. O. longistaminata and the species in the O. officinalis, O. meyeriana and O. ridleyicomplexes contain a partial element. It is proposed that partial deletion of the Tourist-CatA occurred in the ancestor of O. longistaminata and the species in the O. officinalis, O. meyeriana and O. ridleyi complexes after theevolutionary divergence of the ancestor of the AA genome Oryza species, except for O. longistaminata, from the common ancestor of Oryza species. The evolutionary pathway of Oryza species was thus inferred from the phylogeneticanalyses of CatA and its orthologs using the p-SINE1-like intron and Tourist-CatA.Thesis (Ph. D. in Science)--University of Tsukuba, (B), no. 1604, 2000.3.24Includes bibliographical references (p. 45-52)Studies on genetic divergence of catalase genes in plants ~ 岩本, 政
