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Pathological categorization of the stem‐pitting and mild strains Citrus tristeza virus in Taiwan and their genomic analysis
Author(s) -
Lin ChunYi,
Chen YingHua,
Wu MengLing,
Su HongJi,
Hung TingHsuan
Publication year - 2018
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/jph.12704
Subject(s) - citrus tristeza virus , biology , cultivar , strain (injury) , closterovirus , horticulture , virology , plant virus , virus , anatomy
Citrus tristeza virus ( CTV ), the causal agent of tristeza disease, causes the devastating diseases worldwide. In Taiwan, complex cultivars and long‐term infection by CTV result in more than 90% of infected citrus trees, but local strain identification and classification are still incomplete. Here, six CTV strains were categorized by grafting onto eight citrus cultivars and the pathological characteristics of the stem‐pitting mild strains were identified. After 6 months of inoculation, the pummelo stem‐pitting severe strain ( CTV ‐Pum/ SP /T1) only caused severe symptoms in Wentan pummelo (WP) and the mild strain ( CTV ‐Pum/M/T5) was symptomless in every cultivar; the sweet orange (SO) stem‐pitting severe strain ( CTV ‐SwO/ SP /T7) affected SO, WP and Ponkan mandarin (PM), and the mild strain ( CTV ‐SwO/M/T51) caused no symptoms in SO except for WP; the mandarin stem‐pitting severe strain ( CTV ‐Man/ SP /T46) caused severe impacts in PM, WP and Eureka lemon, whereas the mild strain ( CTV ‐Man/M/T2) only caused severe stem‐pitting in WP. The full‐length sequencing of both pummelo stem‐pitting strains and phylogenetic analysis revealed that CTV ‐Pum/ SP /T1 and CTV ‐Pum/M/T5 were related to the HA 18‐9 and HA 16‐5 strains from Hawaii, respectively. Moreover, recombination analysis revealed that TCT repeat sequences existed at open reading frame 1a in both the CTV ‐Pum/ SP /T1 and the T36 strains from the United States, indicating that the possible evolution relationship between two regions. Furthermore, improved universal and specific primer pairs were designed for more specific, sensitive detection to meet the needs for quarantine and early prevention. The understanding of strain pathogenicity and genomic analysis provided further characterization of each strain and enabled practical challenge inoculation against CTV disease.