Biology subjects

Will, T.

Publications and source records attributed to Will, T..

4 recordsLinked to original sources

bioRxiv2024

Genetic diversity in vector populations influences the transmission efficiency of an important plant virus

The transmission efficiency of aphid-vectored plant viruses can differ between aphid populations. Intra-species diversity (genetic variation, endosymbionts) is a key determinant of aphid phenotype; however, the extent of which intra-species diversity contributes towards variation in virus transmission efficiency is unclear. Here, we use multiple populations of two key aphid species that vector barley yellow dwarf virus (BYDV) strain PAV (BYDV-PAV), the grain aphid (Sitobion avenae) and the bird cherry-oat aphid (Rhopalosiphum padi), and examine how diversity in vector populations influences virus transmission efficiency. We use Illumina sequencing to characterise genetic and endosymbiont variation in multiple S. avenae and R. padi populations and conduct BYDV-PAV transmission experiments to identify links between intra-species diversity in the vector and virus transmission efficiency. We observe limited variation in the transmission efficiency of S. avenae, with transmission efficiency consistently low for this species. However, for R. padi we observe a range of transmission efficiency and show that BYDV transmission efficiency is influenced by genetic diversity within the vector, identifying 542 SNPs that potentially contribute towards variable transmission efficiency in R. padi. Our results represent an important advancement in our understanding of the relationship between genetic diversity, vector-virus interactions, and virus transmission efficiency.

pathology↗

bioRxiv2023

High-resolution mapping of Ryd4Hb, a major resistance gene to Barley yellow dwarf virus from Hordeum bulbosum

Virus diseases are causing high yield losses in crops worldwide. The Barley yellow dwarf virus (BYDV) complex is responsible for one of the most widespread and economically important viral diseases of cereals. While no complete resistance gene has been uncovered in the primary genepool of barley, sources of resistance were identified in the wild relative Hordeum bulbosum, representing the secondary genepool of barley. One such locus, Ryd4Hb, has been previously introgressed into barley, and was allocated to chromosome 3H, but is tightly linked to a sublethality factor that prevents the incorporation and utilization of Ryd4Hb in barley varieties. To solve this problem, we fine-mapped Ryd4Hb and separated it from this negative factor. We narrowed the Ryd4Hb locus to a 66.5 kbp physical interval in the barley Morex reference genome. The region comprises one complete and one partial gene from the nucleotide-binding and leucine-rich repeat immune receptor family, typical of dominant virus resistance genes. The closest homolog to these two Ryd4Hb candidate genes is the wheat Sr35 stem rust resistance gene. In addition to the fine mapping, we reduced the sublethality factor interval to 600 kbp in barley. Aphid feeding experiments demonstrated that Ryd4Hb provides a direct resistance to BYDV rather than a resistance to its vector. The presented results, including the high-throughput molecular markers, will permit a more targeted selection of the resistance in breeding, enabling the use of Ryd4Hb in barley varieties. Key messageWe mapped Ryd4Hb in a 66.5 kpb interval in barley and dissociated it from a sublethality factor. These results will enable a targeted selection of the resistance in barley breeding.

plant biology↗

bioRxiv2022

Lack of self-medication by fungus infected Lasius platythorax ants in a multitrophic experiment

Ants live in dense colonies with low genetic diversity between nestmates, creating favourable conditions for the spread of diseases. Due to the constant pressure by infectious disease, ants have evolved different mechanisms to cope with it. One way to combat pathogens is via consumption of biologically active compounds, which can inhibit the growth of the microbes or eliminate them. Although ants are known to respond to pathogen infections by altering their foraging to incorporate reactive oxygen species (ROS) into their diet to successfully combat disease under laboratory conditions, it is still unknown how ants would self-medicate in the wild. By designing a multitrophic environment, we try for the first time to identify potential sources of medicinal compounds for ants to use against fungal infections under natural conditions to better understand how the behaviour is expressed in nature. We investigated whether a bean plant suffering from an infestation of Megoura viciae aphids would be a source of ROS which the ant could use for self-medication, and whether the ant Lasius platythorax changes its foraging behaviour on bean plants if exposed to infectious spores of the entomopathogenic fungus Beauveria bassiana. We found no clear evidence that the ants significantly change their foraging behaviour on extrafloral nectaries in response to the pathogen or that the nectar produced by aphid stressed plants contains ROS. The aphids contained ROS in levels which ants could potentially use, however Megoura viciae is considered unpalatable to ants and we saw no evidence of predation on the aphids. Our results mean that the combination of species of the ant - plant - aphid interactions which we studied does result in a detectable self-medication response in ants. Therefore, we suggest that alternative species of aphids as well as other natural sources of ROS should be studied for self-medication.

animal behavior and cognition↗

bioRxiv2019

Phloem-mediated spreading of SIGS-derived non-coding RNAs in Hordeum vulgare

Small (s)RNA molecules are crucial factors in the communication between hosts and their interacting pathogens/pests that can modulate both host defense and microbial virulence/pathogenicity known as cross-kingdom RNA interference (ckRNAi). Consistent with this, sRNAs and their double-stranded (ds)RNA precursors have been adopted to control plant diseases through exogenously applied RNA biopesticides, known as spray-induced gene silencing (SIGS). While RNA spray proved to be effective, the mechanisms underlying the transfer and uptake of SIGS-associated RNAs are inadequately understood. Moreover, the use of the SIGS-technology as a biopesticide will require the systemic spreading of dsRNA/siRNA signals. Our results strongly support the notion of phloem-mediated long-distance movement of SIGS-associated dsRNA and/or siRNA. These findings are significant contributions to our mechanistic understanding of RNA spray technology, as our previous data indicate that SIGS requires the processing of dsRNAs by the fungal RNAi machinery. In summary, our findings support the model that SIGS involves: (i) uptake of sprayed dsRNA by the plant (via stomata); (ii) transfer of apoplastic dsRNAs into the symplast (DCL processing into siRNAs); (iii) systemic translocation of siRNA or unprocessed dsRNA via the vascular system (phloem/xylem); (iv) uptake of apoplastic dsRNA or symplastic dsRNA/siRNA depending on the lifestyle/feeding behavior of the pathogen/pest.

plant biology↗