Eizo Maeda

Bio: Eizo Maeda is an academic researcher from Nagoya University. The author has contributed to research in topics: Callus & Kinetin. The author has an hindex of 19, co-authored 131 publications receiving 1450 citations. Previous affiliations of Eizo Maeda include Tokyo University of Agriculture.

Regulation of somatic embryogenesis in long-term callus cultures of sugarcane (Saccharum officinarum L.)

Abstract: summary Embryogenically competent callus was induced from in vitro grown Saccharum officinarum L. (NCo 310) plantlets by plating young leaf segments on MS basal medium supplemented with 30 μM dicamba for 21 d in darkness, and subsequently transferring to a medium (EFDM) on which embryos could form and develop. Embryogenic response was improved if the EFDM was supplemented with 1 or 5 μM dicamba, casein hydrolysate (1 g 1−1), and 6% maltose or 6–9% corn syrup. Calli maintained their embryogenic competence for up to 16 months under these conditions, and with alternate weekly subcultures on to fresh media containing 20 μM and 30 μM dicamba in the dark, embryogenic callus proliferation could be further increased. Additional improvements in embryogenic competence were optimized to over 40 months when primary callus was alternately precultured at weekly intervals either with 10-5 M ABA or 5% sorbitol and then transferred to a medium containing 20 or 30 μM dicamba during maintenance. In general, medium plant growth regulator and nutritional cues, especially dicamha concentration, maltose/corn syrup levels and ABA/sorbitol preconditioning, were observed to influence critically both embryogenic callus proliferation and the frequency of somatic embryogenesis. The data are discussed within the context that these treatments can be successfully manipulated to enhance long-term embryogenic competence and high-frequency somatic embryogenesis in sugarcane.

Somatic embryogenesis and plant regeneration in Carica papaya L. tissue culture derived from root explants.

Abstract: The regeneration potential of shoot tip, stem, leaf, cotyledon and root explants of two papaya cultivars (Carica papaya cv. 'Solo' and cv. 'Sunrise') were studed. Callus induction of these two cultivars of papaya showed that the shoot tips and stems are most suitable for forming callus, while leaves, cotyledons and roots are comparatively difficult to induce callus. Callus induction also varied with the varities. Somatic embryogenesis was obtained from 3-month-old root cultures. A medium containing half strength of MS inorganic salts, 160 mg/l adenine sulfate, 1.0 mg/1 NAA, 0.5 mg/1 kinetin and 1.0 mg/1 GA3 was optimal for embryogenesis. The callus maintained high regenerative capacity after two years of culture on this medium. Plants derived from somatic embryos were obtained under green-house conditions.

Shoot Differentiation in Callus of Oryza sativa L.

Abstract: Summary Cyto-histological differentiation, which leads to the formation of adventitious shoots in loci on the periphery of Oryza sativa callus was studied in relation to changes in the external morphology of the tissue The first histological event observed immediately after transfer to the shoot-forming medium was the induction of tissue in which the cells were radially arranged At a more advanced stage, procambium and vascular tissue, stratified outermost cell layer, trichomes, tiny protuberances and chloroplasts appeared in the callus periphery In the latter stage, many leaf primordium-like structures were directly initiated on the callus surface Shoot apices eventually arose from the areas which contained the leaf primordium-like structures

Callus Formation and Isolation of Single Cells from Rice Seedlings

Abstract: 1. This experiment was designed to elucidate the course and the rate of callus production in rice seedlings and to study the single cells isolated from the callus under sterile conditions. Nutrition used here contained 10 μM 2, 4-D, 10 μM NAA, 10 μM kinetin, 5g/1 yeast extract and the basal medium of the modified Murashige and Skoog's (Table 1). 2. Vigorous callus formation was not induced by NAA but 2, 4-D (Fig. 1). Nutritional requirements for the development of callus resulted in the use of yeast extract (Table 2). When the small pieces excised from rice callus were subcultured or rice seeds were cultured for prolonged periods, they developed a huge callus producing a lot of roots with root hairs (Figs. 3 and 4). The fresh weight of rice seedlings with callus increased about 20 fold in 50 days; namely, a seed of 30 mg developed to a lump of callus of 600 mg or more during the incubation period (Fig. 15). From detailed observations on the process of callus formation, it was ascertained that the callus is induced not only from the scutellum or coleoriza but also from the basal regions of the coleoptiles, leaf tissues and root apicles (Figs 5 to 12). 3. Many single cells were freely separated from the callus in suspension culture by rotating the tubes in which the callus and the medium were contained at 1 rpm. The cells were stained with Delafield's hematoxylin, neutral red or methylene blue. The size and form of the cells were observed microscopically. The length and the width of the single cells (means of 100 cells) were 41.1 and 18.8μ, respectively (Table 3). The single cells were of various forms; round, rectangular, crooked and very long. Protuberances similar to budding in unicellular organisms were observed in the single cells. Many pairs of divided cells suggested that longitudinal division occured in the single cells (Figs 13 and 14). 4. The callus and the single cells separated from rice seedlings will provide a system that is of interest in genetical and cell physiological studies on rice plants.

Loss of function of a rice brassinosteroid insensitive1 homolog prevents internode elongation and bending of the lamina joint.

Abstract: Brassinosteroids (BRs) are plant growth–promoting natural products required for plant growth and development. Physiological studies have demonstrated that exogenous BR, alone or in combination with auxin, enhance bending of the lamina joint of rice. However, little is known about the function of endogenous BR in rice or other grass species. We report here the phenotypical and molecular characterization of a rice dwarf mutant, d61, that is less sensitive to BR compared to the wild type. We cloned a rice gene, OsBRI1, with extensive sequence similarity to that of the Arabidopsis BRI gene, which encodes a putative BR receptor kinase. Linkage analysis showed that the OsBRI1 gene is closely linked to the d61 locus. Single nucleotide substitutions found at different sites of the d61 alleles would give rise to amino acid changes in the corresponding polypeptides. Furthermore, introduction of the entire OsBRI1 coding region, including the 5′ and 3′ flanking sequences, into d61 plants complemented the mutation to display the wild-type phenotype. Transgenic plants carrying the antisense strand of the OsBRI1 transcript showed similar or even more severe phenotypes than those of the d61 mutants. Our results show that OsBRI1 functions in various growth and developmental processes in rice, including (1) internode elongation, by inducing the formation of the intercalary meristem and the longitudinal elongation of internode cells; (2) bending of the lamina joint; and (3) skotomorphogenesis.

Rice Plant Development: from Zygote to Spikelet

Abstract: Rice is becoming a model plant in monocotyledons and a model cereal crop. For better understanding of the rice plant, it is essential to elucidate the developmental programs of the life cycle. To date, several attempts have been made in rice to categorize the developmental processes of some organs into substages. These studies are based exclusively on the morphological and anatomical viewpoints. Recent advancement in genetics and molecular biology has given us new aspects of developmental processes. In this review, we first describe the phasic development of the rice plant, and then describe in detail the developmental courses of major organs, leaf, root and spikelet, and specific organs/tissues. Also, for the facility of future studies, we propose a staging system for each organ.

Erect leaves caused by brassinosteroid deficiency increase biomass production and grain yield in rice.

Abstract: New cultivars with very erect leaves, which increase light capture for photosynthesis and nitrogen storage for grain filling, may have increased grain yields. Here we show that the erect leaf phenotype of a rice brassinosteroid-deficient mutant, osdwarf4-1, is associated with enhanced grain yields under conditions of dense planting, even without extra fertilizer. Molecular and biochemical studies reveal that two different cytochrome P450s, CYP90B2/OsDWARF4 and CYP724B1/D11, function redundantly in C-22 hydroxylation, the rate-limiting step of brassinosteroid biosynthesis. Therefore, despite the central role of brassinosteroids in plant growth and development, mutation of OsDWARF4 alone causes only limited defects in brassinosteroid biosynthesis and plant morphology. These results suggest that regulated genetic modulation of brassinosteroid biosynthesis can improve crops without the negative environmental effects of fertilizers.

Progress in Botany

Abstract: Biodiversity is a challenging field of research. Approaches are manifold and mostly cover few aspects of the total wealth of phenomena only. The mapping of the vascular plants and the inventory of Basidiomycota in Bavaria are projects to be mentioned in this context as one part of the commitment of the author. In the following article the author describes further activities during his lifework in regard A. Bresinsky (*) Institute of Botany of University of Regensburg, D-93040, Regensburg, Germany e-mail: abresinsky@t-online.de U. Lüttge et al. (eds.), Progress in Botany, Progress in Botany 75, DOI 10.1007/978-3-642-38797-5_1, © Springer-Verlag Berlin Heidelberg 2014 3 to ant–plant interactions resulting in dispersal and distribution of plants, and moreover, in respect to speciation and to evolution of high ranked taxa within the fungi, discussed mainly in relation to the genus Pleurotus and the order Boletales. In fungi the investigations include breeding systems, isolation barriers, polyploidy, pigment patterns and DNA phylogeny. The pigment patterning in Boletales correlates well with the phylogeny as revealed by DNA analysis of selected gene sections.

Developing Cell and Tissue Culture Systems for the Improvement of Cereal and Grass Crops

Abstract: Summary Recent advances in cell culture and molecular biology of higher plants, which are key components of plant biotechnology, have demonstrated the considerable power and potential of these technologies in the genetic modification and improvement of plants that can not be accomplished by conventional genetic methods. This has stimulated a great deal of interest and activity in university as well as corporate research laboratories. Nevertheless, the fact remains that most of the success achieved so far has been with model plant species and the transfer of these new technologies to major crop species that are the principal targets of biotechnology has either been slow and difficult, or is non-existent. In order to have any meaningful impact on agriculture the developing biotechnology must be equally and readily applicable to important crop species. The cereals and grasses, which constitute the most important group of crop plants, have until recently been found to be very recalcitrant to cell culture techniques. This article describes the advances made in cell culture of important members of this group of crop species. It highlights the success achieved in establishing totipotent callus and cell suspension cultures, and reports the development of protoplast culture systems yielding somatic embryos and plants and the recent recovery of somatic hybrid cell lines and genetically transformed cell lines. The importance of the age and physiological state of the explant, and the relative genetic stability of embryogenic cultures and regenerated plants is discussed.