Walter Chitarra | PubMed Health

PubMed2026

Complete genome sequence of a novel alternavirus infecting Fusarium falciforme.

We present the complete genome sequence of a novel alternavirus, tentatively named "Fusarium falciforme alternavirus 1 (FfAV1)", isolated from Fusarium falciforme. The host, F. falciforme strain Fod375, was isolated from a soil sample in Spain in 2012 and was found to be infected with a virus containing a tetra-segmented double-stranded (ds) RNA genome. The genome segments, designated as dsRNA1 (3529 bp), dsRNA2 (2641 bp), dsRNA3 (2459 bp), and dsRNA4 (1471 bp), each possess a single open reading frame (ORF). The protein predicted from dsRNA1 contains the typical domains of an RNA-dependent RNA polymerase (RdRP) homologous to those of previously reported alternaviruses, while the protein predicted from dsRNA3 shows homology to alternavirus capsid proteins. The proteins encoded by dsRNA2 and dsRNA4 are of unknown function. All predicted proteins exhibited the highest sequence identity with their counterparts in Hebei alternavirus and Marquandomyces marquandii alternavirus 1. Phylogenetic analysis supported the placement of this FfAV1 isolate within the genus Alternavirus. Considering these results, we propose that FfAV1, along with the two closely related unassigned alternaviruses, represents a new species within the genus.

Genome, Viral↗

PubMed2024

CRISPR/Cas9-driven double modification of grapevine MLO6-7 imparts powdery mildew resistance, while editing of NPR3 augments powdery and downy mildew tolerance.

The implementation of genome editing strategies in grapevine is the easiest way to improve sustainability and resilience while preserving the original genotype. Among others, the Mildew Locus-O (MLO) genes have already been reported as good candidates to develop powdery mildew-immune plants. A never-explored grapevine target is NPR3, a negative regulator of the systemic acquired resistance. We report the exploitation of a cisgenic approach with the Cre-lox recombinase technology to generate grapevine-edited plants with the potential to be transgene-free while preserving their original genetic background. The characterization of three edited lines for each target demonstrated immunity development against Erysiphe necator in MLO6-7-edited plants. Concomitantly, a significant improvement of resilience, associated with increased leaf thickness and specific biochemical responses, was observed in defective NPR3 lines against E. necator and Plasmopara viticola. Transcriptomic analysis revealed that both MLO6-7 and NPR3 defective lines modulated their gene expression profiles, pointing to distinct though partially overlapping responses. Furthermore, targeted metabolite analysis highlighted an overaccumulation of stilbenes coupled with an improved oxidative scavenging potential in both editing targets, likely protecting the MLO6-7 mutants from detrimental pleiotropic effects. Finally, the Cre-loxP approach allowed the recovery of one MLO6-7 edited plant with the complete removal of transgene. Taken together, our achievements provide a comprehensive understanding of the molecular and biochemical adjustments occurring in double MLO-defective grape plants. In parallel, the potential of NPR3 mutants for multiple purposes has been demonstrated, raising new questions on its wide role in orchestrating biotic stress responses.

Vitis↗