The development of plastids in the albicate parts of variegated leaves of Liriope platyphylla f. variegata hort. was investigated and compared with that of the normal plastids, which made the subject of the previous study (Murakami 1962). The fine structure of the proplastid of albicate plastid in its earliest stage of development is similar to that of the normal part. During the course of the proplastid development, prolamellar bodies consisting of vesicular elements and primordial lamellae are formed. The arrangement of the vesicles, however, is less regular in the prolamellar body of albicate plastids as compared with that of the normal plastids. The lamellae were found to be formed by coalescence of the vesicles of the prolamellar body. The formation of lamellae in albicate plastids is, however, less abundant and ceases at a relatively early stage of development. This seems to arise from the irregular arrangement of the vesicles in prolamellar body. The author wishes to extend his heartful thanks to Ass. Prof. R. Ueda for his kind guidance throughout this work. Thanks are also due to Prof. K. Hayashi of Tokyo University of Education, and Prof. A. Takamiya of University of Tokyo for their interest and valuable suggestions.
The normal and the abnormal stomata on the leaf of Pteridium aquilinunt var. latiusculum were studied. The normal stoma on the diploid or the tetraploid plant is formed as follows: a stomatal initial appears in the dermatogen; dividing once or twice it gives rise to a stomatal mother cell; a stomatal mother cell divides into a pair of cells; they develop into a pair of guard cells differentiated typically. The persistent stomatal mother cell is rarely observable on all diploid and tetraploid plants. It remains undivided, circularly or elliptically shaped, and not thick-walled. The epidermized stoma is rarely observable on the tetraploid plants. In this type a stomatal mother cell divides into a pair of cells but they develop erratically into the epidermis-like cells. They are not raised above the level of the epidermis. Each cell of the epidermized stoma has the wavelike shape, no thick wall and no pore between two cells. The existence of the poreless multicellular stoma is restricted to three of the tetraploid plants. This interesting stoma is characterized by the following features: it is constructed out of many cells (three to more than ten) caused by the further divisions of two cells originating from a stomatal mother cell; guard cells are not differentially thick-walled; no pore is formed; guard cells are stained not so well with Lugol solution; the chloroplast number is variable and sometimes very few; not a normal stoma in structure and function is formed on these three plants. The tetraploid plants bearing this stoma exhibit many other deviations from the normal morphology and physiology. However, such deviations are not specific to three plants but appear on the other tetraploid plants. Also the causes of the occurrence of these anomalous stomata were discussed. The writer wishes to express his cordial thanks to Profs. Drs. M. Kumazawa and I. Harada of Nagoya University for their guidance and encouragement.
1. A colorimetric method to determine the activity of TTC reduction in tissue slices of bean embryo was established. 2. The reduction proceeded at constant rate under aerobic condition as well as under anaerobic condition. 3. The reduction rate increased with reaction temperature till 50°C. The pH of surrounding medium influenced the reaction rate slightly. 4. Plasmolysis with sugar solutions depressed the reaction, whereas urea favoured it at high concentration. Deplasmolysis prior to the reaction stimulated the reduction. 5. Plasmolysis with inorganic salt solutions influenced the reduction in different degrees. At the plasmolysing concentrations, anions affected the reaction in the order of the lyotropic series. No serious order was observed among cations. 6. Relationship between the activity of the reaction and site of the enzymes in the cytoplasm and its colloidal state was discussed.
The detailed cytogenetical studies have been undertaken in 25 members of genus Citrus, for the first time to determine the chromosomal basis of speciation. Inversion heterozygosity has been observed in C. penvisculata. This is the first record of inversion heterozygosity in genus Citrus. Cytomixis is being reported for the first time in this genus. Binucleate PMCs have been observed in some species, their significance in evolution of polyploid forms has been discussed. C. limonia var. Italian round shows inversion bridges, while the other variety, I. oblong does not show any bridge and fragment configuration. This clearly shows the role of inversion in evolution of new forms in Citrus. C. sinensis var. Malta shows occasional breakdown of first division spindle leading to formation of restitution nucleus. The double division of chromosomes have also been observed in Malta. The high pollen sterility (86%) in Marsh grape fruit is genic because fairly regular bivalent formation has been observed. C. Assamensis is a translocation heterozygote showing trivalents, quadrivalents and sexivalent at meiosis. Inversion bridges have also been observed in this case. This, presumably, is the first record of translocation heterozygosity in genus Citrus. A univalent bridge has been observed at anaphase I. The origin of this species has been discussed. The somatic chromosomes in Citrus species vary between 3.5μ and 1μ. Karyotypes differ in different species. The importance of mitotic anomalies, in the production of bud variants, has been emphasized. The inversion heterozygosity has been observed in 8 out of 25 members of genus Citrus. The univalent chromosomes occur in 17 out of 25 members. The pollen sterility in Citrus species varies between 86% (Marsh grape fruit) and 3% (C. rugulosa). The structural hybridity and presence of univalent chromosomes appear to be the main cause of pollen sterility. The evolution in genus Citrus has been discussed in detail. The polyploidy has not played any significant role in evolution. The structural changes, gene mutations and hybridization appear to have dominated the evolutionary history of genus Citrus. The breakdown of meiosis and its significance, with regard to the origin and evolution of nucellar embryony, has been emphasized.
Fertile hybrids with an interchange complex of six chromosomes from crosses between C. corymbosa and either C. tinctoria or C. multicolor yielded progeny with bivalents in the F2 and F3 generations. Two lines from the former hybrid had a “new” genome simulating the one in C. multicolor. Of the three lines from the latter hybrid, one had a “new” genome simulating the one in C. heterophylla and the others had a genome corresponding to the one in one or the other parental species. Chromosome associations in hybrids involving the lines from each interspecific hybrid and either a parental or a non-parental species were the same as those previously observed when these species were hybridized with species having a genome corresponding to the one in each line. The fertility or sterility of hybrids involving each line agreed with expectations based on previous observations on interspecific hybrids. Certain morphological observations on the lines from the interspecific observations were in accord with those made in species whose genomes were presumably present in each line. The line from C. corymbosa×C. multicolor which simulated the latter species in having its genome and the long flowerpedicel associated with this species included a large number of morphological characters from C. corymbosa. The origin of “new” genomes from the two interspecific hybrids has not yet been explained. Furthermore, it is not yet possible to determine if the genomes from these interspecific hybrids are structurally identical either with those being simulated or with those corresponding to a parental species.
The roots of Phaseolus vulgaris were selected for study. The following subcellular components of the meristematic cells were described and discussed: cytoplasmic membrane; plasmodesmata, mitochondria, proplastids, Golgi-apparatus, endoplasmic reticulum, lipid bodies and nucleus.
Les effets létaux embryonnaires dus à l'hypoploïdie et à l'hyperploïdie de chromosomes ont été étudiés en utilisant des souches de translocation, y compris une souche d'XXY avec deux translocations et une souche de translocation mutuelle entre les chromosomes II et III lesquelles ont été trouvées dans notre laboratoire. L'effet létal dû au défaut du chromosome X est représenté aux stades initials, celui dû à l'hypoploïdie pour un bras du chromosome II ou III aux stades moyens et celui dû à l'hyperploïdie pour un bras du même chromosome peut-être aux stades finals au cours du développment embryonnaire. Il y a quelques souches, mutantes géniques ou avec une petite déficience, dans lesquelles les effets létaux sont manifestés analogiquement à ceux dus à l'hypoploïdie et à l'hyperploïdie de chromosomes.
Karyotype of both Labeo gonius and Labeo dero is characterised by the presence of 54 rod shaped chromosomes. The primary and secondary spermatocytes have 27 rounded chromosomes of approximately the same size. In a number of cyprinids a varying number of V-shaped chromosomes have been reported, in addition to rods. Considering each V-shaped chromosome equivalent to two rods in which centric fusion has taken place, it is suggested that originally the cyprinids had 54 rods, a karyotype very much like the one described here in Labeo species.