Toshiyuki Nagata

A complex case of simple leaves: indeterminate leaves co-express ARP and KNOX1 genes

The mutually exclusive relationship between ARP and KNOX1 genes in the shoot apical meristem and leaf primordia in simple leaved plants such as Arabidopsis has been well characterized. Overlapping expression domains of these genes in leaf primordia have been described for many compound leaved plants such as Solanum lycopersicum and Cardamine hirsuta and are regarded as a characteristic of compound leaved plants. Here, we present several datasets illustrating the co-expression of ARP and KNOX1 genes in the shoot apical meristem, leaf primordia, and developing leaves in plants with simple leaves and simple primordia. Streptocarpus plants produce unequal cotyledons due to the continued activity of a basal meristem and produce foliar leaves termed “phyllomorphs” from the groove meristem in the acaulescent species Streptocarpus rexii and leaves from a shoot apical meristem in the caulescent Streptocarpus glandulosissimus. We demonstrate that the simple leaves in both species possess a greatly extended basal meristematic activity that persists over most of the leaf’s growth. The area of basal meristem activity coincides with the co-expression domain of ARP and KNOX1 genes. We suggest that the co-expression of ARP and KNOX1 genes is not exclusive to compound leaved plants but is associated with foci of meristematic activity in leaves.

Metal Ion Homeostasis Mediated by NRAMP Transporters in Plant Cells - Focused on Increased Resistance to Iron and Cadmium Ion

Toshio Sano1, Toshihiro Yoshihara1, Koichi Handa2, Masa H. Sato3, Toshiyuki Nagata1 and Seiichiro Hasezawa2,4 1Faculty of Bioscience and Applied Chemistry, Hosei University 2Graduate School of Frontier Sciences, The University of Tokyo 3Graduate School of Life and Environmental Sciences, Kyoto Prefectural University 4Advanced Measurement and Analysis, Japan Science and Technology Agency (JST) Japan

Gibberellin as a suppressor of lateral dominance and inducer of apical growth in the unifoliate Streptocarpus wendlandii (Gesneriaceae)

Abstract We report on the effects of exogenously applied hormones on the lateral and apical dominance that governs morphogenesis in the unifoliate Streptocarpus wendlandii. In this phenotype, lateral dominance is extreme as the plants only retain a macrocotyledon that develops into a leaf-like phyllomorph by means of a basal meristem and do not show apical growth. Gibberellin applications suppressed the basal meristem activity of the macrocotyledon resulting in an isocotylous seedling with two microcotyledons and caused the formation of a primary phyllomorph, which suggests that the groove meristem, a shoot apical meristem equivalent, is released from apical suppression by the basal meristem. Interestingly, uniconazol, a gibberellin biosynthesis inhibitor, also caused a reduction in basal meristem activity, but without primary phyllomorph formation, suggesting that some gibberellin is required for proper function of the basal meristem. Co-application of gibberellin and cytokinin resulted in two macrocotyledons also without phyllomorph formation, which is similar to previous results for cytokinin-only applications. Thus, cytokinin may act downstream in the regulatory pathway of the basal meristem. Our results suggest that the balance between gibberellin and cytokinin in the cotyledons appears thus as key factor in the regulation of lateral and apical dominance in Streptocarpus. Their interplay may well be the primary explanation for the great diversity in growth form exhibited in species of this genus. Our work shows that small imbalances of hormones in early stages of plant development can have major effects on the final phenotype.

Identification of Amino Acid Residues Essential for Onion Lachrymatory Factor Synthase Activity

Lachrymatory factor synthase (LFS), an enzyme essential for the synthesis of the onion lachrymatory factor (propanethial S-oxide), was identified in 2002. This was the first reported enzyme involved in the production of thioaldehyde S-oxides via an intra-molecular H+ substitution reaction, and we therefore attempted to identify the catalytic amino acid residues of LFS as the first step in elucidating the unique catalytic reaction mechanism of this enzyme. A comparison of the LFS cDNA sequences among lachrymatory Allium plants, a deletion analysis and site-directed mutagenesis enabled us to identify two amino acids (Arg71 and Glu88) that were indispensable to the LFS activity. Homology modeling was performed for LFS/23–169 on the basis of the template structure of a pyrabactin resistance 1-like protein (PYL) which had been selected from a BLASTP search on SWISS-MODEL against LFS/23–169. We identified in the modeled structure of LFS a pocket corresponding to the ligand-binding site in PYL, and Arg71 and Glu88 were located in this pocket.

An Unusual Xylotheque with Plant Illustrations from Early Meiji Japan

An Unusual Xylotheque with Plant Illustrations from Early Meiji Japan. Two unusual wood collections, reported previously in the collections of the Botanical Museum at Berlin-Dahlem and the Royal Botanic Gardens, Kew, take the form of framed plant illustrations painted on boards made from the wood of the species illustrated. We present new finds of very similar wood collections in the Economic Botany Collection of the Harvard University Herbaria, a private collection in the U.K. (Loudon collection), and at the Koishikawa Botanical Garden of the University of Tokyo. A stamp on the reverse of the boards links all five collections to Chikusai Kato, an artist working at Tokyo University (now the University of Tokyo) in early Meiji Japan, under the direction of the preeminent nineteenth century Japanese botanist Keisuke Ito. New evidence from contemporary historical accounts indicates that more than 100 boards were ordered in June 1878 by Hiroyuki Katō, the first president of Tokyo University, most likely to support the early teaching of Western-influenced botanical science in Japan. However, while the boards had clear value for teaching, especially about useful plants, their unusual fusion of Western and Japanese influences also made them desirable craft objects that were collected and given as gifts during the early Meiji era.明治初期に日本で作られた特異な植物図版について　これまでベルリン・ダーレムの植物博物館とイギリス王立キュー植物園に知られていた植物図版は、枠付きの木製の板の上に描かれており、その板はその植物の材を用いられていることで大変特徴的である。最近、同様な植物図版がハーバート大学植物標本館、ロンドン個人コレクション(Loudon氏蔵)と東京大学附属小石川植物園にも見出された。裏面の篆刻印から、これらの植物図版は東京大学創立初期の1878年に当時の著名な植物学者伊藤圭介教授の指導の下に、そこで働いていた植物画家加藤竹斎によって描かれ、制作されたことが分かる。当時の資料などから新たに分かったことは、当初作成された100枚余の植物図版は初代東京大学総長(当時は総理といった)によって、近代的植物科学の教育手段として購入されたと推定される。しかしながら、これら図版は有用植物の教育手段として優れているが、同時に西洋と日本の画法の融合したユニークな図版であることから工芸品としてもみなされ、明治初期には収集されたり、また、贈答品としても用いられていたことが分かった。

A Journey with Plant Cell Division: Reflection at My Halfway Stop

I have studied various aspects of plant cell division for more than 40 years, and here I try to illustrate some foci among them. First, establishment of the induction of cell division in freshly isolated protoplasts from leaves is described, as this is important not only for biotechnology, but also for the cell cycle transition from G0 to S phase, whose importance has not been fully understood yet. The role of plant hormones, auxin and cytokinin, on this process has not been fully elucidated. Secondly, establishment of a model plant cell system of tobacco BY-2 cells and the high level of cell cycle synchrony achieved using this system is also an important theme for me. However, I will not go into details, but instead refer to the two recently published monographs edited by myself (Nagata T, Hasezawa S, Inze D, Biotechnology in agriculture and forestry, vol. 53, Tobacco BY-2 Cells. Springer, Berlin, 2004; Nagata T, Matsuoka K, Inze D, Biotechnology in agriculture and forestry, vol. 58. Tobacco BY-2 cells. From cellular dynamics to omics, Springer, Berlin, 2006). Further, habituation, discovered by Gautheret (Bull Soc Chim Biol 24:13–47, 1942), will be described, and I will describe how recently we have identified key molecules that may play an important role in this process. Finally, I will try to illustrate aspects of heterophylly from our studies on Ludwigia arcuata (Onagraceae). Although heterophylly is thought to be mostly related to cell elongation in leaves and induced by environmental cues, we found that in L. arcuata, it is closely associated with cell division. This system offers an opportunity to understand the role of cell division upon leaf shape determination as affected by environmental cues. Thus, as my scientific issues are always associated with cell division, their aspects and background stories will be described in this chapter.

03-P089 A simple leaf with compound gene expression: Indeterminate leaves co-express ARP and KNOX genes

03-P089 A simple leaf with compound gene expression: Indeterminate leaves co-express ARP and KNOX genes Kanae Nishii, Michael Moeller, Catherine Kidner, Alberto Spada, Raffaella Mantegazza, Hao-Chun Hsu, Toshiyuki Nagata, Chun-Neng Wang 1 National Taiwan University, Taipei, Taiwan 2 Royal Botanic Garden Edinburgh, Edinburgh, United Kingdom 3 Milan University, Milan, Italy 4 Hosei University, Tokyo, Japan