Lignan production inDaphne odora cell cultures

Lignan production in callus and cell suspension cultures ofDaphne odora is reported for the first time. The cell suspension culture produced pinoresinol, lariciresinol, secoisolariciresinol, matairesinol, and wikstromol. The production of matairesinol in the cell suspension culture was much higher than that inDaphne odora stem tissues.Part of this report was presented at the 51th annual meeting of the Japan Wood Research Society, Tokyo, April 2001     

Stereochemistry of matairesinol formation by <Emphasis Type="Italic">Daphne</Emphasis> secoisolariciresinol dehydrogenase

Secoisolariciresinol dehydrogenase activity was detected for the first time from Daphne odora and Daphne genkwa (Thymelaeaceae), which are known to produce optically pure (+)-matairesinol. In sharp contrast, (–)-matairesinol was formed selectively over the (+)-antipode by the secoisolariciresinol dehydrogenase preparation from both D. odora callus and D. genkwa shoots.     

First report of ‘<Emphasis Type="Italic">Candidatus</Emphasis> Phytoplasma malaysianum’ associated with <Emphasis Type="Italic">Elaeocarpus</Emphasis> yellows of <Emphasis Type="Italic">Elaeocarpus zollingeri</Emphasis>

“Elaeocarpus yellows” (ELY) is a widely reported phytoplasma disease of Elaeocarpus zollingeri trees in Japan. The phytoplasma associated with ELY (ELY phytoplasma) had not been identified at the species level because its 16S rRNA sequence had yet to be reported. Here, we report the results of a sequence analysis based on 16S rRNA and secA gene sequences, which showed that the ELY phytoplasma is related to ‘Candidatus Phytoplasma malaysianum’. To our knowledge, this is the first report showing the occurrence of ‘Ca. P. malaysianum’ outside Malaysia and the infection of E. zollingeri by the phytoplasma.     

At5g54160 gene encodes <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> 5-hydroxyconiferaldehyde <Emphasis Type="Italic">O</Emphasis>-methyltransferase

The function of an Arabidopsis thaliana gene, At5g54160 annotated as a caffeic acid O-methyltransferase CAOMT gene was characterized. The recombinant enzyme of this gene (AtOMT1) catalyzed the O-methylation of phenylpropanoid and flavonoid substrates. The specificity constants (k _cat/K _m) for 5-hydroxyconiferaldehyde (5-HCAld) and quercetin were both 0.11 μM⁻¹·min⁻¹. On the other hand, lignins of At5g54160-knockout Arabidopsis mutants lacked syringyl units. In addition, we showed that the gene silencing also resulted in significant accumulation of caffeyl alcohol (CaAlc). These results strongly suggested that At5g54160 gene is involved in syringyl lignin synthesis for the methylation of both 5-hydroxyconiferaldehyde and 3,4-dihydroxyphenyl compound(s). Part of this work was presented at the Annual Meeting of Japan Society for Bioscience, Biotechnology, and Agrochemistry, March 24–27, 2007     

Profiling of phenylpropanoid monomers in developing xylem tissue of transgenic aspen (Populus tremuloides)

Here we describe alterations in the cinnamate/monolignol pathway in three transgenic aspen lines: one with downregulated expression of 4-coumarate:CoA ligase (4CL), one with upregulated expression of coniferaldehyde 5-hydroxylase (CAld5H), and a 4CL downregulated/CAld5H upregulated line. Compared with the wild type, the 4CL downregulated line showed significantly increased levels of p-hydroxycinnamic acids such as p-coumaric, ferulic, and sinapic acids. In contrast, the CAld5H upregulated line had increased content of p-coumaryl and 5-hydroxyconiferyl alcohols. In the 4CL downregulated line, it was likely that most hydroxycinnamic acids were glycosylated. These results strongly suggest that the downregulation of 4CL and upregulation of CAld5H disrupt the metabolic flow through the cinnamate/monolignol pathway and thus alter the amount and structure of its final product, lignin.     

Disease Resistance of Tissue-cultured Seedlings of Rhododendron after Treatment with Streptomyces sp. R-5

An endophytic actinomycete, Streptomyces sp. R-5, which had been isolated from a field-grown rhododendron plant, was used to protect rhododendron seedlings in tissue culture from Pestalotia disease caused by Pestalotiopsis sydowiana. R-5 had intense antagonistic activity against P. sydowiana without adversely affecting the seedlings in glass flasks. A suspension of R-5 was spread on the surface of the multiplication medium in glass flasks in which seedlings were growing. Ten days later, the 4th upper leaf of seedlings was inoculated with P. sydowiana and incubated for 14 days. In controls untreated with R-5, substrate mycelia of P. sydowiana grew on all leaves and stems above and below the 4th leaf within 2–3 days of inoculation. Such growth resulted in the wilting death of 54% of seedlings by 14 days. In contrast, only the inoculated leaves turned brown in ca. 90% of seedlings growing on medium treated with R-5. None of these seedlings died. Thus, treatment of the medium surface with R-5 efficiently protects the seedlings from infection by P. sydowiana. Scanning electron microscopy revealed that substrate mycelia of R-5 grew on and beneath the cuticle of leaves of the treated seedlings. Fluorescent microscopy showed that R-5 was also inside the leaves. Received 8 June 2001/ Accepted in revised form 4 July 2001     

Endemic infections of bovine viral diarrhea virus genotypes 1b and 2a isolated from cattle in Japan between 2014 and 2020

Bovine viral diarrhea virus (BVDV) is a causative agent of bovine viral diarrhea. In Japan, a previous study reported that subgenotype 1b viruses were predominant until 2014. Because there is little information regarding the recent epidemiological status of BVDV circulating in Japan, we performed genetic characterization of 909 BVDV isolates obtained between 2014 and 2020. We found that 657 and 252 isolates were classified as BVDV-1 and BVDV-2, respectively, and that they were further subdivided into 1a (35 isolates, 3.9%), 1b (588, 64.7%), 1c (34, 3.7%), and 2a (252, 27.7%). Phylogenetic analysis using entire E2 coding sequence revealed that a major domestic cluster in Japan among BVDV-1b and 2a viruses were unchanged from a previous study conducted from 2006 to 2014. These results provide updated information concerning the epidemic strain of BVDV in Japan, which would be helpful for appropriate vaccine selection.     

Changes in petiole hydraulic properties and leaf water flow in birch and oak saplings in a CO2-enriched atmosphere

Water relations in woody species are intimately related to xylem hydraulic properties. High CO(2) concentrations ([CO(2)]) generally decrease transpiration and stomatal conductance (g(s)), but there is little information about the effect of atmospheric [CO(2)] on xylem hydraulic properties. To determine the relationship between water flow and hydraulic structure at high [CO(2)], we investigated responses of sun and shade leaves of 4-year-old saplings of diffuse-porous Betula maximowicziana Regel and ring-porous Quercus mongolica Fisch. ex Ledeb. ssp. crispula (Blume) Menitsky grown on fertile brown forest soil or infertile volcanic ash soil and exposed to 500 micromol CO(2) mol(-1) for 3 years. Regardless of species and soil type, elevated [CO(2)] consistently decreased water flow (i.e., g(s) and leaf-specific hydraulic conductivity) and total vessel area of the petiole in sun leaves; however, it had no effect on these parameters in shade leaves, perhaps because g(s) of shade leaves was already low. Changes in water flow at elevated [CO(2)] were associated with changes in petiole hydraulic properties.