Journal of Taiwan Agricultural Research

Author:Ting-Chin Deng*, Chin-Hui Tsai, Yi-Ting Lin, and Chien-Ming Chou

Abstract:

    Zucchini yellow mosaic virus (ZYMV) had been comparatively detected by bioassay, indirect enzyme-linked immunosorbent assay (ELISA), western blot, and reverse transcription-PCR (RT-PCR). Accordingly, a standard operating procedure for detection of ZYMV carried by cucurbit seeds was set. The procedure includes sampling technique and statistical analysis mode for group test, specimen preparation for testing, acceptable methods for ZYMV detection, and formal expression of tested results. To practice the procedure, a seed lot of Cucurbit sp. for quarantine test was tested by ELISA and the proportion of positive was 0.47 ± 0.46% calculated by ‘Seedhealth’ program. ZYMV involved in these positively detected specimens were confirmed by the analysis of RT-PCR and the nucleotide sequencing of RT-PCR products. However, no seedlings from the same seed lot were infected by ZYMV when tested by growing-out test. All tested seeds collected from 9 local commercial cucumber cultivars were detected to be completely negative. Plants of various cucumber cultivars were inoculated with ZYMV, no virus was detected in fruit or seed derived from some resistant cultivars; whereas, ZYMV-infected fruits were harvested from symptomatic plants of susceptible cultivars. The incidence of ZYMV on fresh seeds in infected fruits was estimated to be 26%; even so, the virus became undetectable after dry preservation of the seeds for 15 d. The distribution of ZYMV on fruit of watermelon was observed, and the virus was found in fresh pedicle, fruit base, fruit peel, outer pulp, inner pulp and innermost pulp. Immature seeds contained more virus than that of mature seeds. Regularly, it’s easier to detect ZYMV in seeds of watermelon cv. ‘Tien-Mei-Zen’ than that of ‘Dark Belle’. The virus was still detectable in 60% of the ‘Tien-Mei-Zen’ seeds stored at 10℃ for 1 yr, but the seed transmission rate detected by growing out test was kept 0.

Key words:Standard operating procedure, Virus indexing, Cucumber, Watermelon, Pumpkin

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