Population Structure of the Fusarium graminearum Species Complex from a Single Japanese Wheat Field Sampled in Two Consecutive Years.

The Fusarium graminearum species complex (Fg complex) that consists of at least 11 phylogenetically distinct species contains important Fusarium head blight (FHB) pathogens of wheat and barley worldwide. We obtained members of the Fg complex by sampling from a 500-m2 experimental wheat field in Kumamoto Prefecture, Japan in two consecutive years and assessed them for species identity and trichothecene chemotype. Haplotype diversity was estimated by using 11 variable numbers of tandem repeat (VNTR) markers. In addition to these two samples (group 03W in 2003 and group 04W in 2004), pathogen populations from seed that was harvested in Fukuoka Prefecture and planted in the experimental field in 2002 (group 02WSC) and pathogen populations from seed that was harvested in Nagasaki Prefecture and planted in 2003 (group 03WSC) were analyzed for this study. Forty-six isolates were collected in each group. Most isolates from wheat heads were classified as F. asiaticum; only four isolates were classified as F. graminearum sensu stricto (s. str.). Out of a total of 183 Fg complex strains, 80 isolates (44%) were of the NIV type, while 103 isolates (56%), including all four F. graminearum s. str. isolates, were of the 3ADON type. No 15ADON type isolate was detected in this study. Trichothecene chemotype compositions of 03W and 04W were nearly identical. High gene diversity of F. asiaticum was observed in all groups. Based on the observed low level of fixation index (FST) and high level of effective number of migrants (Nm), distinctive population subdivision of F. asiaticum was not inferred among the four groups. These results suggest that FHB in the experimental wheat field in both 2003 and 2004 was caused by a genetically similar population, which prevails in Kumamoto, Fukuoka, and Nagasaki prefectures.

Development of simple sequence repeat markers for Japanese isolates of Magnaporthe grisea.

We developed nine simple sequence repeat (SSR) markers useful for differentiating Japanese isolates of Magnaporthe grisea through a bioinformatic approach. Repeat sequences in the genome of M. grisea were identified by a Tandem Repeat Finding program. Length polymorphisms at 28 loci were examined, nine of which were selected on the basis of detected polymorphisms. These nine SSR markers showed a Nei's gene diversity ranging from 0.23 to 0.91 among 48 field isolates of two natural populations. These SSR markers are well suited for M. grisea epidemiology and population genetics.

Molecular characterization of the Fusarium graminearum species complex in Japan.

Members of the Fusarium graminearum species complex are important cereal pathogens worldwide and belong to one of at least nine phylogenetically distinct species. We examined 298 strains of the F. graminearum species complex collected from wheat or barley in Japan to determine the species and trichothecene chemotype. Phylogenetic analyses and species-diagnostic polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLPs) revealed the presence and differential distribution of F. graminearum sensu stricto (s. str.) and F. asiaticum in Japan. F. graminearum s. str. is predominant in the north, especially in the Hokkaido area, while F. asiaticum is predominant in southern regions. In the Tohoku area, these species co-occurred. Trichothecene chemotyping of all strains by multiplex PCR revealed significantly different chemotype compositions of these species. All 50 strains of F. graminearum s. str. were of a 15- or 3-acetyl deoxynivalenol type, while 173 (70%) out of 246 strains of F. asiaticum were of a nivalenol type. The possibility of gene flow between the two species was investigated by use of 15 PCR-RFLP markers developed in this study. However, no obvious hybrids were detected from 98 strains examined, including strains collected from regions where both species co-occur.

The phylogeny of Turnip mosaic virus; comparisons of 38 genomic sequences reveal a Eurasian origin and a recent 'emergence' in east Asia.

The genomes of a representative world-wide collection of 32 Turnip mosaic virus (TuMV) isolates were sequenced and these, together with six previously reported sequences, were analysed. At least one-fifth of the sequences were recombinant. In phylogenetic analyses, using genomic sequences of Japanese yam mosaic virus as an outgroup, the TuMV sequences that did not show clear recombination formed a monophyletic group with four well-supported lineages. These groupings correlated with differences in pathogenicity and provenance; the sister group to all others was of Eurasian B-strain isolates from nonbrassicas, and probably represents the ancestral TuMV population, and the most recently 'emerged' branch of the population was probably that of the BR-strain isolates found only in east Asia. Eight isolates, all from east Asia, were clear recombinants, probably the progeny of recent recombination events, whereas a similar number, from other parts of the world, were seemingly older recombinants. This difference indicates that the presence of clear recombinants in a subpopulation may be a molecular signature of a recent 'emergence'.

Ossification of the posterior longitudianl ligament of the cervical spine: subtotal vertebrectomy as a treatment.

If the ossification is localized in the central part of the intervertebral space, anterior decompression surgery of Cloward may be indicated. However, if most posterior ligamentous ossification covers the posterior surface of the vertebral body and the lateral sides, Cloward's method is not indicated. We have developed a method of anterior decompression and fusion surgery to clear the ossified area, resecting the vertebral body (subtotal vertebrectomy). The results were excellent in 3 of 4 patients with preoperative radiculopathy; there were 2 excellent and 16 good results in 22 patients with myelopathy. Of course laminectomy can produce some good effects, but the anterior obstruction removes through the anterior approach. Anterior decompression may be indicated when ossification is localized below the C3--4 intervertebral space, and when the spinal canal is not narrowed in the upper cervical region, even if ossification extends over the whole cervical spine. Laminectomy is advised when ossification involves all levels of the cervical spine, the upper cervical spine is narrowed or the sagittal dimension of the spinal canal is reduced more than 60%.