Pathology of oak-wisteria powdery mildew.

The relationship between oak and wisteria powdery mildew, the reason artificial infection of Wisteria sinensis was difficult, and the identity of the pathogen were investigated. Inoculations of detached leaves of Quercus robur with Erysiphe alphitoides from either W. sinensis or Q. robur were successful. Wisteria floribunda was completely and W. sinensis partially resistant. Isolates from wisteria and oak had similar pathogenicities and matching DNA profiles and hence not separable into formae speciales. Instead, oak mildew now includes wisteria and possibly Sorbaria as hosts. On non-host Brassica and cellulose acetate, conidial germ tube development ceased after formation of terminal appressoria. Only Q. robur supported visible lesions. W. sinensis supported fewer colony forming hyphae (CFH) per conidium and smaller hyphal appressoria. Failure to form visible lesions was due to prevention or termination of CFH and not to inhibition of conidial germination or to a host's hypersensitive reaction. Absorption of antifungal compounds via appressoria from maturing host tissue is discussed. The pathogen's DNA ITS region indicated an identification of Erysiphe alphitoides sensu lato, since some isolates did not completely match E. alphitoides sensu stricto. To rapidly indicate susceptibility, a microscopic examination of young leaves 48 h post inoculation is recommended.

Starmerella caucasica sp. nov., a novel anamorphic yeast species isolated from flowers in the Caucasus.

Taxonomic analysis of budding yeast strains isolated from flowers of Wisteria sinensis (Fabales, Fabaceae) abundantly visited by flying insects, mainly bees in city parks of Baku is described. The isolates forming slightly pink colonies and propagating by budding represent a hitherto unknown yeast species for which the name Starmerella caucasica is proposed. The sequences of the D1/D2 domains of the large subunit rRNA genes and the ITS1-5.8S-ITS2 regions were highly similar in the isolates and indicated a close relationship with Candida kuoi and Starmerella bombicola in the phylogenetic analysis. S. caucasica can be separated from these species by its growth on glucosamine and D-tryptophan, in vitamin-free medium and at 37°C, and its inability to grow on citrate, ethylamine, cadaverine and in media supplemented with 0.01% of cycloheximide. The type strain is 11-1071.1(T). It has been deposited in Centralbureau voor Schimmelcultures (Utrecht, the Netherlands) as CBS 12650(T), the National Collection of Agricultural and Industrial Microorganisms (Budapest, Hungary) as NCAIM Y.02030(T) and the Culture Collection of Yeasts (Bratislava, Slovakia) as CCY 90-1-1(T). The GenBank accession numbers for nucleotide sequences of S. caucasica are JX112043 (D1/D2 domain of the 26S rRNA gene) and JX112044 (ITS1-5.8S-ITS2). Mycobank: MB 800536.

Diversity of rhizobia associated with leguminous trees growing in South Korea.

This study was carried out to examine the diversity of 34 isolates collected from 11 species of leguminous trees growing in South Korea. Phylogenetic relationships between these 34 isolates and reference strains of the Azorhizobium, Bradyrhizobium, Mesorhizobium, Rhizobium and Ensifer/Sinorhizobium were analysed by using 16S rRNA gene sequences. Twenty-one isolates were related to Mesorhizobium, four isolates to Rhizobium, and nine isolates to Bradyrhizobium. But none of isolates were related to Sinorhizobium/Ensifer and Azorhizobium. Robinia pseudoacacia and Amorpha fruticosa were nodulated by various genotypes of rhizobia out of them, most of the isolates belonged to the genus Mesorhizobium. The isolates from Lespedeza bicolar belonged to diverse genera of Mesorhizobium, Rhizobium, and Bradyrhizobium. The isolates from Maackia amurensis and Lespedeza maximowiezii var. tomentella were phylogenetically related to the genera of Bradyrhizobium. PCR-based RAPD method and phylogenetic analysis of the 16S rRNA results revealed a high phylogenetic diversity of rhizobial strains nodulating leguminous trees in South Korea. Also, the relationships between host and bacterial phylogenies showed that only Robinia pseudoacacia, and Wisteria floribunda have significantly unique branch length than expected by chance based on phylogenetic tree.

Diverse rhizobia associated with woody legumes Wisteria sinensis, Cercis racemosa and Amorpha fruticosa grown in the temperate zone of China.

Fifty-nine bacterial isolates from root nodules of the woody legumes Wisteria sinensis, Cercis racemosa and Amorpha fruticosa grown in the central and eastern regions of China were characterized with phenotypic analysis, PCR-based 16S and 23S rRNA gene RFLP, Box PCR and 16S rRNA gene sequencing. Seven main phena were defined in numerical taxonomy, which corresponded to distinct groups within the genera Agrobacterium, Bradyrhizobium, Mesorhizobium and Rhizobium in 16S and 23S rRNA gene PCR-RFLP. The phylogenetic relationships of the 16S rRNA genes supported the grouping results of PCR-RFLP. Most of the isolates from Amorpha fruticosa were classified into two groups closely related to Mesorhizobium amorphae. Seventeen of the 21 isolates from Wisteria sinensis were identified as two groups related to Rhizobium and Agrobacterium. Six out of 10 isolates from Cercis racemosa were identified as a group related to Bradyrhizobium. Our results indicated that each of the investigated legumes nodulated mainly with one or two rhizobial groups, although isolates from different plants intermingled in some small bacterial groups. In addition, correlation between geographic origin and grouping results was found in the isolates from Amorpha fruticosa. These results revealed that the symbiotic bacteria might have been selected by both the legume hosts and the geographic factors.