[Genes encoding hevein-like antimicrobial peptides WAMPs: Expression in response to phytohormones and environmental factors].

We investigated the role of genes of hevein-like antimicrobial peptides of the WAMP family in the protection of wheat plants against biotic and abiotic stress. The semiquantitative RT-PCR method was used to examine the expression of wamp genes in wheat seedlings in response to infection by pathogens and exposure to phytohormones and ions of a heavy metal ion­cadmium. We discovered that wheat germ contamination by harmful fungi significantly increases expression of genes of the wamp family, and the primary transcript is wamp-2. We determined that salicylic acid, rather than methyl jasmonate, induces expression of genes of the wamp family. We showed that abiotic stress induced by cadmium ions inhibits expression of wamp genes in the roots with no effect on their expression in shoots. The results support the protective role of wamp genes in the response of wheat plants to infections by pathogens. In turn, the resistance to abiotic stress induced by cadmium ions does not appear to be associated with expression of genes of the wamp family.

[A single reverse mutation in the 126/183-kda replicase gene of the attenuated tomato strain V-69 of tobacco mosaic virus increases the virus pathogenicity].

To determine the roles of the mutations that were earlier found in the structure of the attenuated tomato strain V-69 of tobacco mosaic virus (TMV), the nucleotide sequences of genomic RNAs of its four pathogenic revertants have been identified and analyzed. The comparison of the structures of viral genomes has demonstrated that all revertants studied have a single reverse mutation at position 1654 relative to the parental TMV strain V-69. This reversion has been introduced into the plasmid construction harboring a full-length cDNA copy of the TMV strain V-69 RNA, and the infective transcripts synthesized in vitro have been tested on TMV-sensitive tomato and tobacco plants. The tests have confirmed that the single reversion at position 1654, which changes the amino acid residue at position 528 of the 126-kDa and 183-kDa proteins of the viral replicase is responsible for the increase in the pathogenicity of revertants compared to the TMV V-69 strain. The mutation at position 1654 of the viral genome may be supposed to be the main factor of the attenuation of TMV strain V-69.

[Construction of a full-length cDNA of tobacco mosaic virus strain V-69 genome]. / Poluchenie polnorazmernoikDNK-kopii genoma virusa tabachnoi mozaili shtamma V-69.

The genome of the tobacco mosaic virus (TMV) strain V-69 was sequenced by us earlier. The comparison of its nucleotide sequence with those of well-known attenuated strains (using published data) demonstrated considerable homology between strain V-69 and tomato strain L of TMV. In this study, full-length cDNA copy of TMV strain V-69 genomic RNA has been cloned in vector pBS(+) under the control of the T7 promoter and with an SmaI site at the 3'-terminus. The in vitro transcription of this construction with the use of phage T7 RNA polymerase in the presence of a cap analog (m7GpppG) has yielded an infectious RNA. This RNA has induced the same symptoms as those caused by TMV strain V-69 in infected indicator plants. Three point mutations inactivating one of two HindIII sites have been introduced into the cDNA. The absence of the HindIII site at position 1449 of the viral nucleotide sequence and the corresponding mutations serve as markers of the construction obtained. The full-length cDNA copy of the TMV strain V-69 RNA can be used both as a research tool and for constructing a vector for transit gene expression.