No detection of seed transmission of citrus tatter leaf virus in 'Meyer' lemon

摘要

Citrus tatter leaf virus (CTLV), a strain of apple stem grooving virus, is a virus of citrus that is of commercial importance for trifoliate orange (Poncirus trifoliata) and trifoliate hybrid rootstocks. Bud-union crease is a CTLV-induced incompatibly symptom observed with these rootstocks and citrus scions which results in stunted tree growth. CTLV is a regulated pathogen for most citrus budwood certification programs worldwide. Due to the requisite virus testing, commercially supplied scion budwood would therefore seldom be a point of contamination. However, citrus rootstocks are primarily propagated by seed and the potential for seed transmission of CTLV in citrus is unclear and remains a potential source of infection. A single, unconfirmed report of seed transmission of CTLV in 'Eureka' lemon (Citrus x limon) exists, and although this report was not of a rootstock cultivar, it does point to the risk of seed transmission in citrus and close relatives in the family Rutaceae. CTLV-positive 'Meyer' lemon (C. x limon) trees in an experimental plot in the Eastern Cape Province of South Africa presented an opportunity to again test seed transmission in citrus. Seed was obtained from the infected 'Meyer' lemon trees, and 1164 seedlings were grown in an insect-secure greenhouse and screened for CTLV in pooled batches by conventional and real-time RT-PCR. No positive samples were detected and results indicated a lack of virus seed transmission in 'Meyer' lemon. Findings of this study are therefore not supportive of CTLV seed transmission in citrus.