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Shimizu T.,University of Tokyo | Shimizu T.,RIKEN | Miyamoto K.,University of Tokyo | Minami E.,National Institute of Agribiological science | And 6 more authors.
Bioscience, Biotechnology and Biochemistry | Year: 2013

Jasmonate plays key roles in plant growth and stress responses, as in defense against pathogen attack. Jasmonoyl-isoleucine (JA-Ile), a major active form of jasmonates, is thought to play a pivotal role in plant defense responses, but the involvement of JA-Ile in rice defense responses, including phytoalexin production, remains largely unknown. Here we found that OsJAR1 contributes mainly to stress-induced JA-Ile production by the use of an osjar1 Tos17 mutant. The osjar1 mutant was impaired in JA-induced expression of JA-responsive genes and phytoalexin production, and these defects were restored genetically. Endogenous JA-Ile was indispensable to the production of a flavonoid phytoalexin, sakuranetin, but not to that of diterpenoid phytoalexins in response to heavy metal stress and the rice blast fungus. The osjar1 mutant was also found to be more susceptible to the blast fungus than the parental wild type. These results suggest that JA-Ile production makes a contribution to rice defense responses with a great impact on stress-induced sakuranetin production.

Motohashi T.,Tokyo University of Agriculture | Nagamiya K.,Tokyo University of Agriculture | Prodhan S.H.,Tokyo University of Agriculture | Nakao K.,Tokyo University of Agriculture | And 12 more authors.
Asia-Pacific Journal of Molecular Biology and Biotechnology | Year: 2010

Saline stress is one of the major factors limiting crop production in the world. Production of salt tolerant crops is, therefore, a significant subject in agribiotechnology. We transformed a Japonica rice (Oryza sativa cv. Nipponbare) and Indica rices (O. sativa cvs. Kasalath and BR5) with a gene encoding catalase, katE, derived from Escherichia coli which decomposes H2O2, one of reactive oxygen species produced by saline stress, and acts as a quencher of damage by H2O2. Rice plants were transformed using Agrobacterium tumefaciens EHA101 carrying pIG121/Hm/katE. The presence of katE gene in transgenic plants was confirmed by PCR, Southern blot and the expression of katE gene was detected by RT-PCR. Catalase activities of katE transgenic T1 plants are about 1.5 to 2.5 fold higher level than those of non transgenic plants. Transgenic plants (T0, T1) of Nipponbare could grow even in 250mM NaCl solution for 14 days and seeds could be obtained when T1 transgenic plants were cultured throughout in 100mM NaCl solution. The transgenic plants of Kasalath and BR5 could grow in 100mM NaCl solution. Non-transformed plants of all cultivars did not grow in 50mM and higher concentrations of NaCl. Production of marker-free transgenic plants is required to get public acceptance. We used MAT Vector to produce marker-free salt tolerant Nipponbare. In MAT Vector System, selection markers are removed by recombinase and only katE remains. We succeeded to produce marker-free transgenic plants which could grow in 200mM NaCl solution. These findings reported here indicate the feasibility of producing salt tolerant transgenic plants to expand available lands for cultivation of crops on earth.

Nagano A.,Tokyo University of Agriculture and Technology | Nagano A.,Japan Medical Materials Corporation | Tanioka Y.,Tokyo University of Agriculture and Technology | Sakurai N.,Japan Medical Materials Corporation | And 6 more authors.
Acta Biomaterialia | Year: 2011

Genetically modified silk fibroin containing a poly-glutamic acid site, [(AGSGAG) 4E 8AS] 4, for mineralization was produced as fibers by transgenic silkworms through systematic transformation of the silkworms. The Ca binding activity and mineralization of the transgenic silk fibroin were examined in vitro, showing that this transgenic silk fibroin had relatively high Ca binding activity compared with native silk fibroin. Porous silk scaffolds were prepared with the transgenic and native silk fibroins. Healing of femoral epicondyle defects in rabbit femurs treated with the scaffolds was examined by observing changes in images of the defects using micro-computed tomography. Earlier mineralization and bone formation were observed with scaffolds of transgenic silk fibroin compared with those of native silk fibroin. Thus, this study shows the feasibility of using genetically modified silk fibroin from transgenic silkworms as a mineralization-accelerating material for bone repair. © 2010 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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