Original Papers

A lignan O-methyltransferase catalyzing the regioselective methylation of matairesinol in Carthamus tinctorius

Toshiaki Umezawa, Safendrri Komara Ragamustari, Tomoyuki Nakatsubo, Shohei Wada, Laigeng Li, Masaomi Yamamura, Norikazu Sakakibara, Takefumi Hattori, Shiro Suzuki, Vincent L. Chiang . . . . . . . 97[PDF]

Lignans are a group of plant phenolic compounds with various biological activities. O-Methylation is a critical step in biosynthesis of these compounds. However, little is known about the O-methyltransferase (OMT) enzymes that catalyze lignan O-methylation. Here, we report the first molecular cloning and characterization of a lignan OMT cDNA in Carthamus tinctorius seeds. The OMT catalyzes regioselective monomethylation of matairesinol to give rise to arctigenin, but not its regioisomer, isoarctigenin, and is designated as C. tinctorius matairesinol OMT (CtMROMT).

Over-expression of MAP3K4, an ABA-inducible Raf-like MAP3K that confers salt tolerance in Arabidopsis

Nariko Shitamichi, Daisuke Matsuoka, Daisuke Sasayama, Tomoyuki Furuya, Takashi Nanmori . . . . . . . 111[PDF]

Gene expression of an Arabidopsis MAPKKK, MAP3Kδ4, is induced by stress treatments, such as high salt, osmosis, drought and cold and the plant hormone, abscisic acid (ABA). ABA treatment also enhances the protein kinase activity of this enzyme. The ABA-mediated inhibition of seed germination was relieved in the transgenic Arabidopsis over-expressing MAP3Kδ4. The transgenic plant also exhibited enhanced tolerance to salt stress. These results suggest that MAP3Kδ4 plays an important role in ABA signaling and stress tolerance.

Identication of an S-RNase binding protein1 (SBP1) homolog of apple (Malus×domestica)

Mai F. Minamikawa, Daisuke Fujii, Hiroyuki Kakui, Nobuhiro Kotoda, Hidenori Sassa . . . . . . . 119[PDF]

S-RNase binding protein1 (SBP1) is reported to be involved in the S-RNase-based self-incompatibility (SI) response in Petunia (Solanaceae), however, SBP1-like protein has not yet been characterized outside Solanaceae. Here we isolated an apple (Malus × domestica) homolog of SBP1, MdSBP1, from pollen RNA by RT-PCR. The amino acid identities among SBP1 proteins of Solanaceae and Rosaceae were 64.0-68.2%. We detected an interaction between recombinant MdSBP1 protein and S-RNase of apple using a pull-down assay.

Application of the acetolactate synthase gene as a cisgenic selectable marker for Agrobacterium-mediated transformation in Chinese cabbage (Brassica rapa ssp. pekinensis)

Ken-ichi Konagaya, Mai Tsuda, Ayako Okuzaki, Sugihiro Ando, Yutaka Tabei . . . . . . . 125[PDF]

In the present study, we investigated the effects of selectable markers on Agrobacterium-mediated transformation in heading Chinese cabbage. By cloning a genomic DNA fragment containing regulatory and coding sequences of the acetolactate synthase (ALS) gene from Chinese cabbage and mutagenizing it to a herbicide-resistant form, we have succeeded in transforming the Chinese cabbage with a selectable cisgene marker. The transformation frequency was similar to frequencies reported using antibiotic-resistant selectable markers and the escape rate was low.

Establishment of Agrobacterium-mediated genetic transformation system in Dahlia

Yuko Otani, Dong Poh Chin, Masahiro Mii . . . . . . . 135[PDF]

Transgenic plants with hygromycin resistance and GUS expression were successfully obtained by inoculating mass of shoot primordia with Agrobacterium tumefaciens strain EHA101 (pIG121-Hm) in two cultivars of dahlia (Dahlia × pinnata), ‘Yamatohime’ and ‘Kokucho’. An efficient Agrobacterium-mediated transformation system thus established will be applied for wide range of dahlia cultivars to produce transgenic plants with useful genes.

Highly ecient system for plant regeneration from leaf and stem explants in Dahlia

Yuko Otani, Chuki Endo, Dong Poh Chin, Masahiro Mii . . . . . . . 141[PDF]

Protocol of plant regeneration from leaf and stem explants was established in dahlia (Dahlia × pinnata) ‘Yamatohime’ in in vitro culture. A tissue with numerous shoot primordial structures called ‘mass of shoot primordia’ (MSP) was successfully obtained through the nodular callus formation from the explants on MS medium containing 10 mg l-1 TDZ. The MSP showed high plant regeneration ability after transfer onto hormone-free MS medium, and the regenerated plants flowered normally.

Proteomic analysis of stress-related proteins in rice seeds during the desiccation phase of grain lling

Naoto Sano, Shunpei Masaki, Takanari Tanabata, Tetsuya Yamada, Tadashi Hirasawa, Motoki Kanekatsu . . . . . . . 147[PDF]

To understand the mechanism of desiccation tolerance in seeds, the fluctuation of stress-related proteins in developing rice seeds were analyzed by a real-time RT-PCR and proteomic approach. The proteomic analysis revealed that late embryogenesis abundant proteins, small heat shock proteins and antioxidative proteins are involved in acquisition of desiccation tolerance. In addition, the fluctuation in levels of mRNA encoding some stress-related proteins did not precisely reflect the change in levels of these proteins.

Characterization of 5-Hydroxyconiferaldehyde O-Methyltransferase in Oryza sativa

Taichi Koshiba, Norie Hirose, Mai Mukai, Masaomi Yamamura, Takefumi Hattori, Shiro Suzuki, Masahiro Sakamoto, Toshiaki Umezawa . . . . . . . 157[PDF]

There is a substantial difference among caffeic acid O-methyltransferases (CAOMTs) from different gramineous plants with respect to substrate preference. We characterized reactions catalyzed by an Oryza sativa CAOMT (OsCOMT1) and a chemotype of transgenic O. sativa in which the OsCOMT1 was downregulated, and found indications that OsCOMT1 was in fact a 5-hydroxyconiferaldehyde OMT (OsCAldOMT1).

ATL54, a RING-H2 domain protein selected by a gene co-expression network analysis, is associated with secondary cell wall formation in Arabidopsis

Soichiro Noda, Yoshinori Takahashi, Yuta Tsurumaki, Masaomi Yamamura, Nobuyuki Nishikubo, Masatoshi Yamaguchi, Nozomu Sakurai, Takefumi Hattori, Hideyuki Suzuki, Taku Demura, Daisuke Shibata, Shiro Suzuki, Toshiaki Umezawa . . . . . . . 169[PDF]

We found that Arabidopsis thaliana ATL54 was co-expressed with the genes that encode several transcription factors and enzymes involved in secondary wall formation. A recombinant ATL54 protein showed ubiquitin ligase activity. The expression levels of several secondary wall biosynthetic genes and Xylem Cysteine Peptidasel in inflorescence stems were altered by ATL54 knock-out and overexpression. Our results suggest that ATL54 is an E3 ubiquitin ligase involved in secondary wall biosynthesis and programmed cell death during xylogenesis.

Short Communication

Hybrid lethality with programmed cell death results from reciprocal interspecic crosses between Nicotiana nudicaulis Watson and N. tabacum L.

Hongshuo Liu, Misato Hoshio, Yusuke Masaki, Yojiro Mori, Wataru Marubashi . . . . . . . 179[PDF]

Hybrid seedlings from reciprocal interspecific crosses between Nicotiana nudicaulis and N. tabacum were not viable when cultured at 28℃ and did not exhibit any symptoms of lethality at 34℃. Therefore, hybrid lethality associated with these crosses was due to the interaction of coexisting heterologous genomes and not to a cytoplasmic effect. Furthermore, hybrid lethality of N. nudicaulis × N. tabacum seedlings is accompanied by apoptotic cell death.


Comparison of indole derivatives as potential intermediates of auxin biosynthesis in Arabidopsis

Yosuke Ishida, Ayako Nakamura, Yuka Mitani, Masashi Suzuki, Kazuo Soeno, Tadao Asami, Yukihisa Shimada . . . . . . . 185[PDF]

Biosynthesis pathways and intermediates of the most abundant auxin, indole-3-acetic acid (IAA), have not been completely understood. We examined 11 indole derivatives whether they are indeed IAA intermediates by measuring their effects on recovery from auxin-deficiency conditions caused by an IAA biosynthesis inhibitor, L-aminooxyphenylpropionic acid. The results provide information on which compounds are reliable intermediates of IAA biosynthesis pathways in Arabidopsis.

High-level gene expression in dierentiating xylem of tobacco driven by a 2.0 kb Poplar COMT2 promoter and a 4×35S enhancer

Enying Liu, Shaobing Peng, Quanzi Li, Ying-Hsuan Sun, Vincent L. Chiang, Ronald R. Sedero . . . . . . . 191[PDF]

Promoter constructs with high levels of xylem specific expression are needed to obtain efficient expression of candidate genes, microRNAs (miRNAs) and artificial microRNAs (amiRNAs) for the genetic modification of wood properties. The gene for caffeic acid O-methytransferase (PtrCOMT2) has the second most abundant transcript level of all the genes in monolignol biosynthesis in Populus trichocarpa and a high level of specificity in differentiating xylem. To characterize the PtrCOMT2 promoter, we cloned a short (2.0 kb) and a long (3.3 kb) promoter segment and compared their expression using GUS as a reporter gene in the differentiating xylem of Nicotiana tabacum. Both the 2.0kb and the 3.3kb promoter segments showed high specificity for differentiating xylem in this heterologous system.

Cationic peroxidase related to basal resistance of Betula platyphylla var. japonica plantlet No. 8 against canker-rot fungus Inonotus obliquus strain IO-U1

Yuya Takashima, Miho Suzuki, Futoshi Ishiguri, Kazuya Iizuka, Nobuo Yoshizawa, Shinso Yokota . . . . . . . 199[PDF]

This study investigated the time-course changes of the in situ peroxidase (POD) distribution and expression of POD isozymes in Betula platyphylla var. japonica plantlet No.8 infected with a canker-rot fungus, Inonotus obliquus strain IO-U1. The obtained results suggest that cationic POD isozymes are related to the basal resistance in B. platyphylla var. japonica plantlet No.8 against infection with I. obliquus strain IO-U1.