Characterization of a new Anulavirus isolated from Amazon lily plants.

A quasi-spherical virus was isolated from a cultivated Amazon lily plant (Eucharis grandiflora) that could be mechanically transmitted to healthy E. grandiflora plants, subsequently producing mild mosaic or mottle symptoms on the leaves. The purified virus consisted of three quasi-spherical particles about 20 nm wide and 70, 40 and 30 nm in length, containing three segmented genomes of 3,169, 2,507 and 2,530 nucleotides, respectively. Sequence analysis showed that the newly isolated virus is related to pelargonium zonate spot virus, a member of the genus Anulavirus. We propose that the virus should be designated as Amazon lily mild mottle virus (ALiMMV).

Complete nucleotide sequence of the new potexvirus "Alstroemeria virus X". Brief report.

A flexuous virus was isolated in Japan from an alstroemeria plant showing mosaic symptoms. The virus had a broad host range but had systemically latent infectivity in alstroemeria. The virus was assigned to the genus Potexvirus based on morphology and physical properties and on an analysis of the complete nucleotide sequence. The genomic RNA of the virus was 7,009 nucleotides in length, excluding the 3'-terminal poly (A) tail. It contained five open reading frames (ORFs), which was consistent with other members of the genus Potexvirus. Although nucleotide sequences of the ORFs differ from previously reported potexviruses, a phylogenetic analysis placed it phylogenetically close to Narcissus mosaic virus and Scallion virus X. Therefore, we propose that this virus should be designated as Alstroemeria virus X (AlsVX).

Nucleotide sequence of the coat protein genes of alstroemeria mosaic virus and amazon lily mosaic virus, a tentative species of genus potyvirus.

The nucleotide sequences of the 3' terminal region of the genomes of Alstroemeria mosaic virus (AlsMV) and the Amazon lily mosaic virus (ALiMV) have been determined. These sequences contain the complete coding region of the viral coat protein (CP) gene followed by a 3'-untranslated region (3'-UTR). AlsMV and ALiMV share 74.9% identity in the amino acid sequence of the CP, and 55.6% identity in the nucleotide sequence of the 3'-UTR. Phylogenetic analysis of these CP genes and 3'-UTRs in relation to those of 79 potyvirus species revealed that AlsMV and ALiMV should be assigned to the Potato virus Y (PVY) subgroup. AlsMV and ALiMV were concluded to have arisen independently within the PVY subgroup.

Pea Tissue Necrosis Induced by Cucumber mosaic virus Alone or Together with Watermelon mosaic virus.

Necrotic diseases of the stems, petioles, and leaves of pea plants (Pisum sativumL.), leading to wilting and death, occur in the Wakayama and Mie Prefectures of Japan. Based on host range, symptomatology, electron microscopy, and serological relationships, Watermelon mosaic virus (WMV) and three Cucumber mosaic virus (CMV) isolates (PE2, PE3A, and PB1) were isolated from diseased plants in the Wakayama Prefecture. In the Mie Prefecture, CMV (PEAN) also was isolated from pea plants with similar symptoms. Single infection with CMV (PB1 or PEAN) caused stem necrosis and eventual death of pea plants. Similar symptoms developed after double infection with WMV and PE2 or PE3A, whereas single infection with PE2 and PE3A induced symptomless infection in pea plants. We concluded either CMV alone or synergistic effects of mixed infection with CMV and WMV induced pea plant stem necrosis.

Transformation of pBR322-Derived Plasmids in PhytopathogenicPseudomonas avenae and Enhanced Transformation in ItsProline-Auxotrophic Mutant

Efficient transformation of pBR322 and its derivedplasmids, which have been widely used as cloning vectors in Escherichiacoli, was observed in Pseudomonas avenae (K1), the pathogen ofleaf blight disease in cereals. Moreover, there was a 10- to 50-foldtransformation efficiency (1.3-3.0 x 10(6)/&mgr;g DNA) in theproline-auxotrophic mutant (Pr47), whose virulence to rice seedlingsdecreased. Similar enhancement of the frequency of transfer by mobilizationof RSF1010, a broad host range plasmid, was observed in the recipient Pr47strain in mating with donor Pseudomonas syringae. The plasmidsharbored in these strains were maintained very stably after subcultures.Thus, a highly efficient transformation system with pBR322-derived plasmidsused as a vector and Pseudomonas as a host bacterium was developed.

Effect of protectants in L-drying on the conformation and infectivity of rice dwarf phytoreovirus.

Purified rice dwarf phytoreovirus preparations, after rehydration following drying without freezing (L-drying) and sucrose density gradient centrifugation, sedimented to the same position as untreated controls. Upon storage at 65 degrees C, virion conformation in L-dried preparations supplemented with 1% sucrose was maintained better than without additives. Moreover, during storage for 6 years at -70 degrees C, infectivity of L-dried preparations from crude extracts of infected rice plants containing 5% sucrose was higher than controls based on the number of count of infected foci on cell monolayers and transmission to rice seedlings by leafhopper of the vector Nephotettix cincticeps, which had been injected with such extracts.

Nucleotide sequence of segment S9 of the rice dwarf virus genome.

The complete nucleotide sequence of genome segment S9, which was reported as the ninth largest among the 12 genome segments of rice dwarf virus, was determined. The segment was 1,305 bp long and coded for a protein composed of 351 amino acids (Mr 38,930). The terminal sequences of the segment were found to consist of an imperfect 14 base pair inverted repeat located at positions 2-15 and 1289-1302, which is similar to that identified in other reoviruses.