Minor Variants of Orf1a, p33, and p23 Genes of VT Strain Citrus Tristeza Virus Isolates Show Symptomless Reactions on Sour Orange and Prevent Superinfection of Severe VT Isolates

The control of tristeza quick decline (QD) of citrus is based on the use of rootstocks that are tolerant or resistant to the Citrus tristeza virus (CTV), but some of them show bio-agronomic limits. The application of cross-protection (CP) has been insufficiently explored. The present study examined...

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Bibliographic Details
Published in:Viruses 2023-09, Vol.15 (10), p.2037
Main Authors: Licciardello, Grazia, Scuderi, Giuseppe, Russo, Marcella, Bazzano, Marina, Bar-Joseph, Moshe, Catara, Antonino F
Format: Article
Language:English
Subjects:
Asymptomatic
Citrus
Citrus fruits
Cross-protection
Diagnosis
Diseases and pests
Genes
Genetic aspects
Genetic relationship
genome sequencing
Genomes
Genotype & phenotype
Greenhouses
Infections
Inoculation
Mutation
quick decline
Rootstocks
Superinfection
superinfection exclusion
Trees
Virus diseases
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Summary:The control of tristeza quick decline (QD) of citrus is based on the use of rootstocks that are tolerant or resistant to the Citrus tristeza virus (CTV), but some of them show bio-agronomic limits. The application of cross-protection (CP) has been insufficiently explored. The present study examined the possibility of QD control by cross-protection (CP) following reports showing the dependence of the CP strategy on the close genetic relationships between the protective and challenging CTV isolates. Taking advantage of deep sequencing technologies, we located six naturally infected trees harboring no-seedling yellow (no-SY) and no QD decline (mild) VT isolates and used these for challenge inoculation with three QD VT isolates. Symptom monitoring showed that all six Sicilian mild no-SY isolates, based on their genomic relatedness and mild symptoms reactions, provide effective protection against the three severe local VT isolates. The differences between the six mild and three severe isolates were confined to just a few nucleotide variations conserved in eight positions of three CTV genes (p23, p33, and Orf1a). These results confirm that the superinfection exclusion (SIE mechanism) depends on close genetic relatedness between the protective and challenging severe VT strain isolates. Ten years of investigation suggest that CP could turn into an efficient strategy to contain CTV QD infections of sweet orange trees on SO rootstock.
ISSN:1999-4915
1999-4915
DOI:10.3390/v15102037