An intergeneric hybrid between Er. orientale and Ae. squarrosa was reported. The spike shape of the F1 was intermediate between the parents but the spikelets showed the characters of Eremopyrum. In the majority of cells no chromosome pairing was observed. Average chromosome pairing was 0.1II+20.8I. This shows that the genomes of Er. orientale are quite different from the D-genome of Ae. squarrosa.
The effects of nitrosoguanidine on Bacillus subtilis were studied. Lethal damage produced by nitrosoguanidine was repairable in the sense that the repair was inhibited by acriflavine. Mutation was induced more efficiently at the initial period of the treatment when the killing effect was not high. The repairable damage seems to have little connection to the potent mutagenic action of nitrosoguanidine. It was also found that less amount of DNA could be isolated from nitrosoguanidine-treated cells, and the genetic linkage was lowered in the DNA isolated from treated cells, as compared with DNA isolated from untreated cells. It was postulated from these results that nitrosoguanidine would produce some unknown damage on DNA or on some other cellular components which would then act to induce mutation at very high efficiency.
The length at maturity of various organs and other agronomic characters were measured in 33 mutant lines radiation-induced from a rice variety, Norin 8, which were selected for high fertility and yield. Principal components were extracted from the genetic correlations of organ length. The first component showed an “isometric” phase of variation (general size), in which various organs varied proportionally in length. The second vector showed a variation in the relative length of organs (“allometry”). In this phase of variation, the organs in a stem sequentially increased or decreased in relative length from the top to the base, bringing about the contrast between “upper- elongation” and “lower-elongation” types. In the same manner as in our previous work on F3 lines, the α (“panicle-number” vs. “panicle-length” type, the former having more but smaller panicles and leaves than the latter) and the β (“internode-length” vs. “internode-number” type, the former having fewer but longer internodes and more erect leaves than the latter) variations in plant type were obtained from the mutant lines, when the data for panicle number and mean internode length were adjusted by the score for general size. The α and β plant-type scores were correlated with the scores showing general size and differential relative size of organs, respectively. Possibly, variations in agronomic characters of cereal crops may be largely conditioned by such an isometric and an allometric factor, the former involving the size-number relationship of stems, and the latter representing sequential change in the relative length of organs in a stem.
Between-line variations in the final size, the time at which half of the final size was attained (t1/2), and the growth rate at t1/2, were studied for the panicle and first to fourth (from the top) internodes. Materials used were 23 mutant lines radiation-induced from a rice variety, Norin 8, which were selected for high fertility and yield. For each of the above three values, principal components were extracted from correlations between the five organs, and the “genetic vectors” showing genetic contributions of the components to the respective organs were computed. In the final size, as reported in our previous paper, two latent phases of genetic variation were distinguished, one showing the general size (isometry), and the other showing an allometric pattern that brought about the variation between “upper-elongation” and “lower-elongation” types. Variations in the growth rate of organs similarly comprised an isometric and an allometric phase. Lines with a generally high growth rate had a large general size at maturity. In the allometric phase, lines whose panicle and third internode elongated relatively slowly had a relatively high growth rate for the first and second internodes. Such lines tended to be the “upper-elongation” types at maturity. As the panicle and third internode elongate some days before the elongation of first and second internodes that results in heading, the allometric pattern of growth rate suggests that the lines vary in the rhythm of development. This was proved by an observation of the change of relative growth rate in the period from panicle elongation to heading. It was suggested that genes modify the rhythm of development and bring about the size variations observed at maturity.
1. Four kinds of quadruple monosomics and one kind of quintuple monosomics were produced by a systematic procedure in a variety Chinese Spring of common wheat, Triticum aestivum ssp. vulgare. 2. Quadruple monosomics (17II+4I) were selected in the progeny of the cross between triple monosomics (18II+3I) and a nullisomic, which lacks the fourth pair of chromosomes. The quadruple monosomics were pollinated with pollen grains of a nullisomic, which lacks the fifth pair of chromosomes, and in their F1's quintuple monosomics (16II+5I) were selected. 3. Quadruple monosomics were more or less smaller in size, and reduced in vigor with somewhat later maturity, but they were fertile in both sexes. Quintuple monosomics were still inferior to the quadruple monosomics in their various characters, though they retained reproductive ability. 4. Crosses between quadruple monosomics (_??_) and normal plants (_??_) were made to maintain the quadruple monosomic strains; F1's obtained had 38 to 42 chromosomes. The 38-chromosome plants appeared at a frequency of 21.2 per cent, and showed the 17II+4I chromosome configuration at meiotic metaphase I, which indicated that they were quadruple monosomics. 5. The present results indicated that the female gametes with the least chromosome number in expectation participate at a high frequency in fertilization in every kind of hypoaneuploids, so far produced in hexaploid wheat.
The author has analyzed data on the annual increase in stature of the same individual throughout the school years to observe the manifestation of genes controlling stature. 1. The correlation coefficient r'i•j between the height at maturation and at various ages during growth becomes gradually higher with the decreasing difference in age; but the variation of r'i•j-curve follows that of nth degree, and is not additive or of linear increase, for the correlation momentarily decreases with the onset of the adolescent spurt (Figs. 1 and 2). In all of the 9 samples, the corresponding r'i•j-curves show much the same tendency. 2. A strong negative correlation (r=-0.81--0.97) is seen between r'i•j and the national average of the growth of stature per year by age. And, the smallest r'i•j corresponds to the maximum period of the maximum growth rate. 3. The strong correlation is found in Yoshida's data (1944) between parent-child correlation of the stature of children by age and r'i•j (r=0.79-0.88). In Takiguchi's data (1945) also, a similar tendency is seen in r'i•j (Figs. 1 and 2) as for the correlation of stature between mature elder brothers and 15-19 year old younger brothers, but because of the absence of data on brothers younger than 14 years, it is not certain whether a perfect concordance may be found or not. 4. The variation in parent-child or intersib correlation is regarded as one of the factors that contributed to the difference of these values in past reports. 5. A negative correlation (ri•jp) is usually found between statures in growth period and yearly growth by age, during the most rapid period of growth: 10-13 in males and 9-12 years in females. 6. These facts suggest that the manifestation of genes controlling stature at the completion of growth differs with age (and sex), and that this manifestation is modified by other factors at spurt. 7. Compared at the same age, a strong and regular correlation may be found between cotwins, both identical and fraternal, and for all ages. Otuki's report (1956) of the parent-child correlation of stature compared at the same age also has presented no variation by age. Therefore, it is suggested that the pattern of the growth of stature is under the control of genes, and that these genes may be considered to be fairly independent of those controlling the stature at the completion of the stature. 8. For the study of the influences of consanguineous marriage or of radiation upon stature, a through observation throughout the whole growth period is desirable.