Marcos Giovanni Celli

Rice yellow mottle virus (RYMV) is one of the most devastating viral pathogens affecting rice cultivation in Africa. The eukaryotic translation initiation factor 4G isoform eIFiso4G1 plays a pivotal role in rice susceptibility to the virus. Naturally occurring resistance alleles impair infection but are predominantly found in the African cultivated species Oryza glaberrima , whose use in breeding programs is limited by interspecific sterility barriers with the widely grown O. sativa . Here, we used CRISPR/Cas9 to generate knockout (KO) mutations in eIFiso4G1 as well as insertion-deletion (Indel) variants within the region involved in interaction with the viral protein VPg. KO mutations conferred high resistance to RYMV. No resistance-breaking events were observed, suggesting that this resistance may be more durable than that conferred by naturally occurring alleles. However, complete gene KO slightly affected plant growth. Lines carrying Indel mutations in the VPg-interacting region displayed variable resistance levels, with some variants conferring high resistance without compromising plant development. Structural modeling of the eIFiso4G1 variants and their complexes with VPg provided mechanistic insights into how specific Indels modulate the resistance phenotype.

This study reports the first record of Frankliniella zucchini Nakahara & Monteiro (Thysanoptera: Thripidae) in Argentina. This thrips, previously confirmed as the only vector for Zucchini Lethal Chlorosis Virus (ZLCV), was identified on squash crops (Cucurbita maxima Duch.) in the northeastern subtropical region of Argentina, infected with ZLCV, the causal agent of lethal chlorosis of zucchini squash. In addition, the present study presents the morphological characteristics distinguishing F. zucchini from the morphologically similar Frankliniella gemina Bagnall, along with factors that may influence the potential spread of this ZLCV-bearing thrips to other favorable regions. Currently, the primary factor limiting its global spread appears to be the restricted host range of F. zucchini.

Rice yellow mottle virus (RYMV) is one of the most devastating viral pathogens affecting rice cultivation in Africa. The eukaryotic translation initiation factor 4G isoform eIFiso4G1 plays a pivotal role in rice susceptibility to the virus. Naturally occuring resistance alleles impair infection but are predominantly found in the African cultivated species Oryza glaberrima, whose use in breeding programs is limited by interspecific sterility barriers with the widely grown O. sativa. Here, we used CRISPR-Cas9 to generate knockout (KO) mutations in eIFiso4G1 as well as insertion-deletion (Indel) variants within the region involved in interaction with the viral protein VPg. KO mutations conferred high resistance to RYMV. No resistance-breaking events were observed, suggesting that this resistance may be more durable than that conferred by naturally occuring alleles. However, complete gene KO slightly affected plant growth. Lines carrying Indel mutations in the VPg-interacting region displayed variable resistance levels, with some variants conferring high resistance without compromising plant development. Structural modeling of the eIFiso4G1 variants and their complexes with VPg provided mechanistic insights into how specific Indels modulate the resistance phenotype.

While rice necrosis mosaic virus (RNMV) has only been described in Asia, we identified this virus on a rice plant from Argentina using a viral metagenomic approach. We further confirmed this result by RT-PCR and small-RNA Illumina sequencing to obtain the near-complete genome and to confirm actual infection by RNMV.

The first rice virus detected in Argentina was Rice stripe necrosis virus (RSNV), a benyvirus known to cause "entorchamiento" due to its characteristic symptom of leaf crinkling. As part of this st...

The rice stripe necrosis virus (RSNV) has been reported to infect rice in several countries in Africa and South America, but limited genomic data are currently publicly available. Here, eleven RSNV genomes were entirely sequenced, including the first corpus of RSNV genomes of African isolates. The genetic variability was differently distributed along the two genomic segments. The segment RNA1, within which clusters of polymorphisms were identified, showed a higher nucleotidic variability than did the beet necrotic yellow vein virus (BNYVV) RNA1 segment. The diversity patterns of both viruses were similar in the RNA2 segment, except for an in-frame insertion of 243 nucleotides located in the RSNV tgbp1 gene. Recombination events were detected into RNA1 and RNA2 segments, in particular in the two most divergent RSNV isolates from Colombia and Sierra Leone. In contrast to BNYVV, the RSNV molecular diversity had a geographical structure with two main RSNV lineages distributed in America and in Africa. Our data on the genetic diversity of RSNV revealed unexpected differences with BNYVV suggesting a complex evolutionary history of the genus Benyvirus.

Virus species of the genus Orthotospovirus are among the most economically important plant pathogens in the world because they cause severe crop losses; mainly, in ornamental and horticultural crop...