Wheat and barley are the most highly produced and consumed grains in the world. Various pathogens—viruses, bacteria, fungi, insect pests, and nematode parasites—are major threats to yield and economic losses. Strategies for the management of disease control mainly depend on resistance or tolerance breeding, chemical control, and biological control. The discoveries of RNA silencing mechanisms provide a transgenic approach for disease management. Host-induced gene silencing (HIGS) employing RNA silencing mechanisms and, specifically, silencing the targets of invading pathogens, has been successfully applied in crop disease prevention. Here, we cover recent studies that indicate that HIGS is a valuable tool to protect wheat and barley from diseases in an environmentally friendly way.

Positive-sense RNA viruses have a small genome with very limited coding capacity and are highly reliant on host factors to fulfill their infection. However, few host factors have been identified to participate in wheat yellow mosaic virus (WYMV) infection. Here, we demonstrate that wheat (Triticum aestivum) light-induced protein (TaLIP) interacts with the WYMV nuclear inclusion b protein (NIb). A bimolecular fluorescence complementation (BIFC) assay displayed that the subcellular distribution patterns of TaLIP were altered by NIb in Nicotiana benthamiana. Transcription of TaLIP was significantly decreased by WYMV infection and TaLIP-silencing wheat plants displayed more susceptibility to WYMV in comparison with the control plants, suggesting that knockdown of TaLIP impaired host resistance. Moreover, the transcription level of TaLIP was induced by exogenous abscisic acid (ABA) stimuli in wheat, while knockdown of TaLIP significantly repressed the expression of ABA-related genes such as wheat abscisic acid insensitive 5 (TaABI5), abscisic acid insensitive 8 (TaABI8), pyrabatin resistance 1-Llike (TaPYL1), and pyrabatin resistance 3-Llike (TaPYL3). Collectively, our results suggest that the interaction of NIb with TaLIP facilitated the virus infection possibly by disturbing the ABA signaling pathway in wheat.

Autophagy-related 8 (ATG8) protein has been reported to be involved in plant’s innate immune response, but it is not clear whether such genes play a similar role in cereal crops against obligate biotrophic fungal pathogens. Here, we reported an ATG8 gene from wheat (Triticum aestivum), designated TaATG8j. This gene has three copies located in chromosomes 2AS, 2BS, and 2DS. The transcriptions of all three copies were upregulated in plants of the wheat cultivar Suwon 11, inoculated with an avirulent race (CYR23) of Puccinia striiformis f. sp. tritici (Pst), the causal fungal pathogen of stripe rust. The transient expression of TaATG8j in Nicotiana benthamiana showed that TaATG8j proteins were distributed throughout the cytoplasm, but mainly in the nucleus and plasma membrane. The overexpression of TaATG8j in N. benthamiana slightly delayed the cell death caused by the mouse apoptotic protein BAX (BCL2-associated X protein). However, the expression of TaATG8j in yeast (Schizosaccharomyces pombe) induced cell death. The virus-induced gene silencing of all TaATG8j copies rendered Suwon 11 susceptible to the avirulent Pst race CYR23, accompanied by an increased fungal biomass and a decreased necrotic area per infection site. These results indicate that TaATG8j contributes to wheat resistance against stripe rust fungus by regulating cell death, providing information for the understanding of the mechanisms of wheat resistance to the stripe rust pathogen.

The small open reading frames (ORFs) embedded in lncRNA have been identified to encode biologically functional peptides in many species. However, the function of lncRNA‐encoded small peptides in the plant antiviral response remains unclear. In this study, an lncRNA Talnc54748 was identified, which encodes the small peptide ORF4. Transgenic Nicotiana benthamiana overexpressing ORF4 could enhance wheat yellow mosaic virus (WYMV) infection. RNA‐sequencing analysis revealed that many genes in plant hormone signalling and MAPK signalling pathways were reduced in ORF4 ‐overexpressing lines. The function of SAUR21 and MKK2 , involved in plant hormone signalling and MAPK signalling pathways, respectively, was investigated by virus‐induced gene silencing assay. Silencing SAUR21 or MKK2 in wheat and N. benthamiana enhanced WYMV infection. Transgenic overexpression of ORF4 not only enhanced the accumulation of tobacco mosaic virus (TMV) and tomato mosaic virus (ToMV), but also promoted Phytophthora capsici or Pseudomonas syringae pv. tomato DC3000 infection. Our results demonstrated that an lncRNA‐encoded small peptide plays an important role in plant immunity and provides new insights into the roles of this lncRNA‐encoded small peptide in the plant antiviral response.

In China, wheat yellow mosaic disease is mostly caused by wheat yellow mosaic virus (WYMV) and Chinese wheat mosaic virus (CWMV). If wheat is co-infected with these two viruses, it can cause severe yellow mosaic symptoms and yield losses. Early detection of viruses is crucial for preventing disease in the field. In this study, we optimized a sensitive, specific reverse transcription recombinase polymerase amplification (RT-RPA) detection method for two viruses, WYMV and CWMV. Two sets of primers were designed based on the capsid protein (CP)-encoding genes of the two viruses, and the reaction conditions were determined. The RT-RPA method, which amplified the target amplicon by a handheld reaction mixture for 20 min, was more sensitive than PCR-CP in the detection of WYMV. Finally, the RT-RPA method was performed on 110 randomly selected field samples, demonstrating its applicability to samples from different regions and specificity for co-infected samples. This study not only describes an improved method for detecting WYMV and CWMV using RT-RPA but also demonstrates the potential of this method, which could be applied under field conditions.