Articles
Pathogenic characterization of a VT no-SY variant of Citrus tristeza virus repressing the replication of a homologous SY isolate in sour orange seedlings
Article number
1448_74
Pages
591 – 602
Language
English
Abstract
The use of sour orange (SO) as rootstock was prevalent in Italy until the outbreak of Citrus tristeza virus (CTV) VT isolates.
Few of them induce seedling yellow (SY) on SO and others no (no-SY). VT no-SY isolates share 99% homology at genomic level with VT SY variants, showing only minor variations on Orf1a, p23, and p33 genes, and repress the super-infection of SY isolates.
With the aim to investigate the mechanism of cross-protection we have studied a set of SO seedlings pre-inoculated with a no-SY isolate (M39D) and challenged after 11 months with an SY isolate (P7). Different approaches were included based on biological indexing, virus genome reconstruction, real-time RT-PCR high-resolution melting (HRM) assay and transcriptomic analysis.
The viral genome reconstruction and the HRM assay, designed on the G/A mutation of the p23 gene, evidenced a blockage of the SY isolate infection process in plants pre-inoculated with the no-SY isolate.
A mechanism confirmed at biological level by back inoculation of SO seedlings with bark tissues taken from superinfected plants.
Transcriptome analysis based on RNA-seq showed more than 3,000 differentially expressed transcripts (DETs) in plants inoculated with the P7 SY isolate versus uninoculated plants.
On the contrary, the plants inoculated with the M39D and those superinfected with the P7 showed only 16 and 58 DETs, respectively.
These data indicate that the reduction of SY symptoms is associated with the reduction in the number of up- and downregulated genes and that the M39D isolate induces in SO a plant immune response distinct and less severe than the homologous aggressive isolate.
Few of them induce seedling yellow (SY) on SO and others no (no-SY). VT no-SY isolates share 99% homology at genomic level with VT SY variants, showing only minor variations on Orf1a, p23, and p33 genes, and repress the super-infection of SY isolates.
With the aim to investigate the mechanism of cross-protection we have studied a set of SO seedlings pre-inoculated with a no-SY isolate (M39D) and challenged after 11 months with an SY isolate (P7). Different approaches were included based on biological indexing, virus genome reconstruction, real-time RT-PCR high-resolution melting (HRM) assay and transcriptomic analysis.
The viral genome reconstruction and the HRM assay, designed on the G/A mutation of the p23 gene, evidenced a blockage of the SY isolate infection process in plants pre-inoculated with the no-SY isolate.
A mechanism confirmed at biological level by back inoculation of SO seedlings with bark tissues taken from superinfected plants.
Transcriptome analysis based on RNA-seq showed more than 3,000 differentially expressed transcripts (DETs) in plants inoculated with the P7 SY isolate versus uninoculated plants.
On the contrary, the plants inoculated with the M39D and those superinfected with the P7 showed only 16 and 58 DETs, respectively.
These data indicate that the reduction of SY symptoms is associated with the reduction in the number of up- and downregulated genes and that the M39D isolate induces in SO a plant immune response distinct and less severe than the homologous aggressive isolate.
Publication
Authors
G. Licciardello, D. Puglisi, G. Lopatriello, V. Grosso, M. Caruso, M. Bazzano, G. Scuderi, M. Russo, A.F. Catara, P. Caruso, M. Rossato, C. Licciardello
Keywords
cross-protection, superinfection exclusion, RNA-seq, high resolution melting, nucleotide polymorphism, seedling yellows
Groups involved
Online Articles (103)