FLEXIBLE AND DIGESTIBLE WOOD CAUSED BY VIRAL-INDUCED ALTERATION OF CELL WALL COMPOSITION

ABSTRACT: Woody plant material represents a vast renewable resource that has the potential to produce biofuels and other bio-based products with favourable net CO2 emissions1,2. Its potential has been demonstrated in a recent study that generated novel structural materials from flexible mouldable wood3. The study of viral infection in plants has largely focussed on detrimental symptoms, such as leaf yellowing or cell death that result in reduced crop yields. Apple rubbery wood (ARW) disease is the result of a viral infection that causes woody stems to exhibit increased flexibility4. While ARW disease is associated with the presence of an RNA virus5 (ARWV), the mechanism underlying the development of its unique symptoms is not known. We demonstrate that ARWV symptoms arise from reduced lignification within the secondary cell wall of xylem fibres, while the mid-lamellae region and xylem ray cells are largely unaffected, and results in increased wood digestibility. Gene expression and proteomic data from symptomatic xylem clearly show the downregulation of phenylalanine ammonia lyase (PAL), the enzyme catalysing the first committed step in the phenylpropanoid pathway leading 2 to lignin biosynthesis. PAL downregulation is the likely cause of the decreased lignification, which is consistent with a large increase in soluble phenolics, including the lignin precursor phenylalanine, seen in symptomatic xylem. ARWV-infection results in the accumulation of many host-derived viral activated small interfering RNAs (vasiRNAs). PAL-derived vasiRNAs are among the most abundant vasiRNAs in symptomatic xylem and are likely the cause of reduced PAL activity. Apparently, the mechanism used by the virus to alter lignin exhibits similarities to the RNAi strategy that has been used to alter lignin in genetically modified trees to generate comparable improvements in wood properties6–8. CRISPR technology was recently used to increase yields in maize by introducing the naturally occurring waxy mutation into maize9. A similar biomimetic approach for biomass improvement based upon our understanding of ARWV symptoms offers a promising route to improve wood properties and provides important context for the genetic manipulation of trees.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Malus Domestica

TISSUE(S): Xylem

SUBMITTER: Manoj Kumar  

LAB HEAD: Simon Turner

PROVIDER: PXD032356 | Pride | 2022-06-26

REPOSITORIES: Pride