This study was carried out to investigate the developmental changes and the origin of primary and secondary rays in relation to secondary growth of Robinia pseudoacacia, Albizzia julibrissin, Diospyros kaki and Castanea crenata. Primary rays were highly uniseriate and mainly of vertical elongated cells. They were the products of repeated divisions of short cells in the procambium. The first secondary rays arose in the fasciular region at a distance of 500-1000μ from the pith and originated by dividing off the sides or ends of fusiform initials. In R. pseudoacacia ray height increased in the late wood of the first growth ring, and then kept constant after a gradually decreasing in the second growth ring. While in A. julibrissin, D. kaki and C. crenata, ray height remained constant through the secondary growth after marked decrease in the first growth ring. Ray width gradually increased in all samples, however, the number of rays per unit area decreased with exception of D. kaki. The ratio of rays to axial systems gradually increased in R. pseudoacacia, A. julibrissin, and D. kaki. But in C. crenata the height and ratio of rays remained constant throughout the secondary growth.

View full abstract

Genes of the KNOX gene family have the homeo domain and have been revealed to be related to the organogenesis in plants. Based on the results of mRNA and protein in situ hybridization and mutant analyses, the genes closely related to the maize knotted-1 gene were reported to be involved in the shoot differentiation and the compound leaf formation. Redundancy of the genes in the family are observed and it may show the evolutionary dynamics of the gene family. Recent studies on the KNOX genes are reviewed.

View full abstract

Phylogenetic trees are indispensable to understand the evolution of particular characters such as morphological ones. These days, molecular data or information on nucleotide sequences can easily give us reliable phylogentic trees. Therefore, discussion on morphological evolution should be based on molecular phylogenetic trees.Moreover, to reobserve morphological characteres from an evolutionary point of view based on molecular phylogenetic trees can help us to see them in different ways. Thus, molecular phylogentic trees can be useful for the sudies on morphological characters, themselves.

View full abstract

I showed two models for growth strategies of plants growing unpredictable environments. In the first model, I analyzed the evolutionarily stable sapling growth waiting for future gap formation under closed canopy. In the second model, I analyzed the optimal resource allocation strategies to ramets(daughter plants), rhizomes(or other horizontal stems, such as stolons)and seeds for plants growing in a spatially varying environment.

View full abstract

There have been many studies of the structure of the shoot apex and leaf initiation and development in the past.The shoot apex has generally an important role for formation of terrestrial parts of the plant body, and the leaf is the photosynthetic organ. Therefore, we can easily understand the reason that many studies have been done on those problems in the past.The author studied on some problems of the structure of the shoot apex and the leaf initiation and development of Ginkgo leaf, marginal meristem of the leaf, and vein endings of the leaf, etc. The aim of the present article is to review on these problems.

View full abstract

The localization of DNA in the condensed interphase chromosomes and of DNA in the nucleoids of chloroplasts and mitochondria in cells of Euglena was studied by immunoelectron microscopy. Small colloidal gold(5-6nm in diameter)was conjugated with anti-mouse IgM antibodies. Deposits of gold particles on the interphase chromosomes that coincided with the localization of DNA followed threads that corresponded to the chromatin fibers. The threads were50-80nm in diameter. The localization of gold deposits on chromosomes that had been sectioned in various directions suggested that the chromatin fibers coiled around the surface of chromosomes, with a wide central axial region of the chromosomes remaining free of DNA. The structure of the nucleoids in chloroplasts and in mitochondria was very different from those previously observed by conventional electron microscopy. Nucleoids in chloroplasts appeared to be composed of twisted threads50-70nm in diameter. Mostnucleoids in mitochondria were spherical or ovoid, 70-130nm in diameter. Nucleoids both in chloroplasts and in mitochondria contained cores with which DNA threads were in tight contact.

View full abstract

Cells of Euglena contain a light-harvesting chlorophyll a/b complex associated with photosystem II. In Euglena, the formation of the26.5kDa principal light-harvesting chlorophyll a/b binding protein of photosystem II(LHCP II)has a number of unusual features. The precursors to LHCP II are large polyproteins containing multiple copies of LHCP II, and photocontrol of their formation is largely translational. Under conditions favoring LHCP II accumulation in the thylakoids, a reaction with anti-LHCP II antibody can be observed in the Golgi by immunogold electron microscopy. The timing of the immunoreaction in the Golgi in synchronous cells and in cells undergoing normal light-induced chloroplast development suggests that the nascent LHCP II passes through the Golgi on the way to the thylakoids. The compartmentalized osmiophilic structure(COS)also shows an immunoreation. These observations, and others discussed in this paper, suggest that light permits translation of polyprotein LHCP II precursors on cytoplasmic ribosomes of the rough endoplasmic reticulum(ER)and that these pass through the ER to the Golgi where, presumably, further modifications take place. Since an LHCP II immunoreaction is found in Golgi vesicles, these may transport the nascent LHCP II to the plastid and facilitate its uptake.

View full abstract

The appearance of the techniques of developmental genetics is one of the most powerful strategies in efforts to understand the mechanisms of complex biological phenomena, such as leaf morphogenesis. However, developmental genetic analysis alone is insufficient for detailed characterization of the mechanisms that control such morphogenesis. Thus, physiological, biochemical, and biophysical methods must also be applied to the analysis of morphogenetic pathways. An overview of past and potential future studies of leaf morphogenesis is presented.

View full abstract

The sequential mold-cast technique was employed to examine the development of abaxial epidermis, including stomatal complex and multicellular trichomes, of Vigna radiata(Leguminosae). Sequential impressions were made of the abaxial surface of the first foliage leaf at daily intervals to follow leaf development. Casts were made by filling molds with epoxy adhesive, which was polymerized at 60°C for 1hr. Hardened casts were sputtercoated with gold, and viewed with SEM. When very young, the abaxial leaf-epidermis is thoroughly covered with dense wax deposits, which make trichomes and developing stomata invisible from the surface. As the leaf grow, the wax deposits on the epidermis appears to be reduced in amount. Trichome production has finished by the time when the leaf begins to unfold, while stomata are continuously produced until relatively late stage of leaf development.

View full abstract