Barley yellow dwarf Virus-GAV movement protein activating wheat TaATG6-Mediated antiviral autophagy pathway

Beyond movement: expanding functional landscape of luteovirus movement proteins

Viruses explore the potential multifunctional capacity of the proteins encoded in their compact genome to establish infection. P4 of luteoviruses has emerged as one such multifunctional protein. Expressed from an open reading frame (ORF) nested within coat protein ORF, it displays diverse subcellular localizations and interactions, reflecting its complex role in virus infection. In this review we explore how P4, constrained by overlapping ORFs, has evolved multiple functional motifs. We analyze these motifs' conservation across different barley yellow dwarf virus (BYDV) species and related poleroviruses. We also discuss how viral proteins cooperate to facilitate movement and localization of the virus throughout infection. We provide insights into potential future research directions and suggest strategies for developing potential antiviral-resistant approaches.

Catalase regulation during plant-virus-vector interaction

Plant-virus-host interaction is a complex process involving several players. A constant arms race between the hosts and viruses has led to their co-evolution. Reactive oxygen species (ROS) are important signaling molecules that regulate plant growth, development, and stress responses. Barley yellow dwarf virus (BYDV) has a wide host range and infects several plant species such as barley, rice, oats, wheat, etc. A recent study by Tian et al. (2024) has highlighted that the movement protein (MP) of BYDV is involved in manipulation of the host ROS pathway to promote viral multiplication as well as transmission. The findings display the multifaceted role of a viral protein that is otherwise involved in movement. The limited coding ability of viruses is compensated by their proteins having multiple roles in the modulation of several different host molecular pathways. This is one of the key reasons for viruses being successful pathogens despite their limited coding ability.

Barley yellow dwarf virus-GAV 17K protein disrupts thiamine biosynthesis to facilitate viral infection in plants

Thiamine functions as a crucial activator modulating plant health and broad-spectrum stress tolerances. However, the role of thiamine in regulating plant virus infection is largely unknown. Here, we report that the multifunctional 17K protein encoded by barley yellow dwarf virus-GAV (BYDV-GAV) interacted with barley pyrimidine synthase (HvTHIC), a key enzyme in thiamine biosynthesis. HvTHIC was found to be localized in chloroplast via an N-terminal 74-amino acid domain. However, the 17K-HvTHIC interaction restricted HvTHIC targeting to chloroplasts and triggered autophagy-mediated HvTHIC degradation. Upon BYDV-GAV infection, the expression of the HvTHIC gene was significantly induced, and this was accompanied by accumulation of thiamine and salicylic acid. Silencing of HvTHIC expression promoted BYDV-GAV accumulation. Transcriptomic analysis of HvTHIC silenced and non-silenced barley plants showed that the differentially expressed genes were mainly involved in plant-pathogen interaction, plant hormone signal induction, phenylpropanoid biosynthesis, starch and sucrose metabolism, photosynthesis-antenna protein, and MAPK signaling pathway. Thiamine treatment enhanced barley resistance to BYDV-GAV. Taken together, our findings reveal a molecular mechanism underlying how BYDV impedes thiamine biosynthesis to uphold viral infection in plants.