In order to study the phylogeny of Aegilops mutica in the genera of Triticum and Aegilops, variations in chloroplast and mitochondrial DNA regions were investigated by polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) analysis. Nine lines, each of Ae. mutica and Ae. speltoides, were studied together with nine other Triticum and Aegilops species, including T. aestivum. By analyzing 9.7-kb chloroplast and 13.1-kb mitochondrial DNA regions, a total of 268 bands were detected, of which 176 (65.7%) showed variation within and/or between species. The level of intraspecific variation of Ae. mutica was lower than that of Ae. speltoides. The low level of the intraspecific variation of Ae. mutica was contrary to the expectation from previous studies on morphological and cytolo-gical characters. In the phylogenetic trees based on SSCP, Ae. mutica, Ae. speltoides and the other four species of the section Sitopsis (the subsection Emarginata) were separated into three different clusters. In addition, T. aestivum was included in the cluster of Ae. speltoides in the phylogenetic trees. This result suggests that Ae. speltoides is the cytoplasmic donor of common wheat.

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Plasmons (= cytoplasms) of eight Triticum species (ten accessions) and 24 Aegilops species (36 accessions) have been introduced by repeated backcrosses to 12 genotypes of hexaploid, common wheat. At transfer problems such as crossing barrier, preferential transmission of a gametocidal or parthenogenesis-inducing chromosome, and mistagging of the material occurred, all of which hindered the plasmon transfer program. Of the 552 genotype-plasmon combinations produced, 532 (96.4%) had reached the B₁₀ or a later backcross generation, 15 (2.7%) the B₇~B₉ generation, and the remaining 5 (0.9%) the B₄~B₆ generation by summer, 1996. Pollen and selfed seed fertilities were observed in plants of all the field-grown lines in the 1992 - 1993 winter crop season, and backcrossed and selfed seed fertilities of plants grown in a greenhouse under a long day condition (17-h light) were assessed in the five latest backcross generations. Selfed seed fertility was found to be a better parameter of male fertility than was pollen fertility. Female fertility, as estimated from the backcrossed seed fertility, was about three times more tolerant to genetic stress caused by the alien plasmon transfer than was male fertility evaluated from both the pollen and selfed seed fertilities. The plasmons studied could be classified into 14 fertility spectrum groups. Most, excluding 15 plasmons belonging to the B, D, D², S, and S^b plasmon types, were considered the male sterile plasmon to common wheat.

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The inheritance of in vitro shoot regeneration ability in rice seed-callus was studied with the cross combinations between a high and a low regeneration ability cultivar. The mature rice seeds were cultured on 1/2 concentration of MS basal medium containing 3 mg/1 2,4-dichlorophenoxyacetic acid (2,4-D), 5 g/1 yeast extract, 30 g/1 sucrose and ll g/1 agar for callus formation. The formed calli were transferred onto a medium composed of 1/4 concentration of MS plus 1/4 concentration of N₆, supplemented with 2.5 mg/l 1-naphthaleneacetic acid (NAA), 8 mg/1 kinetin, 30 g/1 sucrose and 3 g/1 gelrite for regeneration. The high regeneration ability cultivars Aikoku and Sen-ichi with regeneration rate of more than 85%, and the low regeneration ability cultivar Moritawase with regeneration rate of no more than 2% were used as cross parents. In F₁ progenies, the regeneration ability appeared similar to their high regeneration ability parents, and there was no difference between reciprocal crosses. F₂ and BC₁ populations showed two distinct patterns of regeneration ability, the high and low regeneration ability plants fitted the 3:1 and 1:1 ratio respectively. The results indicate that the difference of regeneration ability between the high and low parents in this study is controlled by a single dominant gene. The F₂ population of Aikoku × Sen-ichi did not show segregation, suggesting that the dominant gene in these two cutivars is the same allele.

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Activation of aniline by plant extracts was studied by a chromosomal damage induction assay in Chinese hamster ovary (CHO) cells in vitro. Extracts from roots of Vicia faba activated aniline and the activation caused increases in chromosomal aberrations (CAs) and endoreduplicated cells (ERCs), but did not cause sister-chromatid exchanges (SCEs). Extracts from Pisum sativum and Lactuca sativa, however, did not activate aniline. All C-hydroxylated metabolites of aniline, o-aminophenol, m-aminophenol and p-aminophenol, induced not only CAs but also SCEs in CHO cells. These results show that the pathway for aniline activation by Vicia extracts is by means other than the C-hydroxylation.

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The entropy evolution rate introduced by Ohya (Ohya, 1989) is one of the measures to classify gene sequences such as DNA sequences or amino acid sequences and to construct phylogenetic trees. The efficiency of this measure for the construction of phylogenetic trees with DNA sequences is examined in this paper. Taking model trees with branches of given evolutionary rates, we generated sequences with 1000 nucleotides along the branches of each model. Computer simulation was performed 100 times for each model. The entropy evolution rate was found to give the correct toplogy of tree more often than other methods when the evolutionary rate of a lineage (branch) was higher than 0.5 par site.

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MtDNAs from BY-2 cells and rice root were analyzed by random amplified polymorphic DNA (RAPD) assay and Southern hybridization analysis. A number of differences were observed in the RAPD patterns amplified from mtDNAs sampled at different phases of the BY-2 cell culture. RAPD fragments also varied with the template DNAs derived from various areas of rice root tip. When a RAPD fragment was hybridized to restriction fragments of whole DNAs, isolated from the distal area of the apical meristem and differentiated elongation zone of a root, two distinct stoichiometric differences were observed in the hybridization signals. This suggests that the organization of mt-genome in prototypic cells in the root apical meristem differs from that found in the differentiated cells.

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