Plant Pathology Science

Geminiviruses (Geminiviridae family) with small circular ssDNA genome are encoding just four to seven proteins on virion and complementary-sense strands of their genomes. To have a progressive infection, they are dependent mostly on host cellular machineries and interact with wide range of different host plants factors and processes. Geminiviruses alter the cell cycle in infected plants and they can support replication of viral DNA. They change host gene expression patterns, inhibit cell death pathways, alter macromolecule trafficking and interfere with protein modification to redirect or suppress host defenses and hormones signaling. Geminiviruses encode gene silencing suppressors to interfere with post-transcriptional gene silencing and alter plant DNA methylation and microRNA (miRNA) pathways, often causing developmental abnormalities. Here, the geminiviruses are discussed as one of the most destructive plant viruses and their proteins interactions with host cell factors and pathways are described.

Plant viruses cause major losses to agricultural crops worldwide. Plants react to the virus infections via several defense mechanisms, such as ubiquitination. Ubiquitin (Ub) and ubiquitin proteasome system (UPS) play key role in the function modification and degradation of proteins in plants. Ub attachment to the cellular proteins alters the stability, the cellular establishment or activity of the target protein. The key role of UPS has been revealed in defense mechanisms and other plant processes. Viruses as obligate intracellular parasites have evolved mechanisms to interfere UPS. In some cases, it has been shown that viral proteins were targeted by this system. Ubiquitination plays an important role in plant–virus interaction which can lead to plant resistance or pathogenicity in the host plant. Therefore, further understanding of UPS and its role in plant-virus interaction can develop novel methods to increase resistance to viral infections in plants.

Yellow mosaic, caused by the Barley Yellow Mosaic Virus (BaYMV), which is transmitted by the fungal-like organism Polymyxa graminis, is one of the most significant viral diseases affecting barley worldwide. To conduct serological and molecular surveillance of this virus in barley fields across Khorasan Razavi Province, northeastern Iran, a total of 86 leaf samples were collected in late winter of 2022. These samples were either randomly selected or exhibited symptoms such as mosaic patterns, chlorosis, and vein clearing. Upon transfer to the laboratory, the samples were analyzed using serological ELISA tests and molecular reverse transcription polymerase chain reaction (RT-PCR) assays. Using BaYMV-specific primers, an 800 base pair fragment corresponding to the viral coat protein was successfully amplified. Among the RT-PCR-positive isolates, the amplified DNA fragment from the Bajestan isolate was extracted from the gel and sequenced. The obtained sequence was verified using the BLAST program and subjected to phylogenetic analysis alongside other BaYMV coat protein sequences available in the NCBI GenBank database, using DNAMAN-7 and Vector NTI software. The sequenced fragment of the Bajestan isolate shared the highest nucleotide (94.79%) and amino acid (90.59%) similarity with a corresponding fragment from a European isolate. This study represents the first report of BaYMV occurrence in Bajestan County, Khorasan Razavi Province, Iran.