|HAJERI, SUBHAS - CENTRAL CALIFORNIA TRISTEZA ERADICATION AGENCY|
|Yokomi, Raymond - Ray|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 5/10/2022
Publication Date: N/A
Interpretive Summary: Citrus tristeza virus (CTV) causes the most economically important virus disease of citrus worldwide. CTV is graft transmissible and is spread in nature by aphid vectors. CTV strain diversity and complexity are described in the context of the different disease syndromes they produce. Antibodies made to the capsid protein are used in Enzyme-Linked Immunosorbent Assay (ELISA) for routine CTV diagnosis. Based on the phylogeny of the complete genomic sequences of CTV, its strains fall into eight broad genotypes. This has resulted in strain-specific diagnosis by various PCR methods. These diagnostic methods now allow rapid molecular characterization and strain differentiation of CTV and supplements biological characterization (virus indexing) which requires months to complete in a controlled environment greenhouse. CTV research has resulted in new knowledge now used to manage CTV diseases and development of new frontiers for plant disease management.
Technical Abstract: Citrus tristeza virus (CTV) is the most economically important virus disease of citrus in the world, having lost more than 100 million trees on sour orange rootstock. The virus primarily spreads by infected budwood and aphid species in a semi-persistent manner. CTV is a member of the Closterovirus genus in the family Closteroviridae and is the largest non-segmented plant RNA virus. Genetic variation between isolates is unevenly distributed along the CTV gRNA, the most conserved region being the 3’-UTR, with over 95% identity and the most variable being the 5’-UTR, with identity values as low as 44%. Based on phylogenetic analysis of the complete genomic sequences, CTV strains fall into broadly eight genotypes. CTV is a regulated Class-A plant pest and a monoclonal antibody (MCA13) is used in ELISA for preliminary screening for potentially severe as well as exotic strains of CTV to California.