Preliminary Identification of Maize Stripe Tenuivirus in Thailand

Maize stripe tenuivirus (MStV) and its planthopper vector, Peregrinus maidis, occur in many tropical and subtropical regions worldwide (2). However, MStV has not been reported from the southeastern Asia continent. In January 1990, five of 200 Sorghum bicolor plants growing in Hat Yai, Thailand, showed symptoms typical of MStV, i.e., chlorotic spots, streaks, and wide bands on the younger leaves. Colonies of P. maidis also were present in leaf whorls of both symptomatic and asymptomatic sorghum plants. In December 1991, two sweet corn plants (Zea mays cv. Thai Super Sweet Composite 1 DMR) growing in the same area showed similar symptoms and were infested with P. maidis. When examined by phase-contrast microscopy, sap from chlorotic leaf tissue of one sweet corn plant had needle-shaped crystals typical of MStV infection (1). Sap from asymptomatic sweet corn plants had no crystals. In April 1996. maize cv. Chieng Mai 90 with MSt-like symptoms and also infested by P. maidis was collected from Hat Yai. Leaves were freeze dried, sent to Ohio, and tested by F(ab')2 enzyme-linked immunosorbent assay (ELISA). Positive control samples were fresh or freeze-dried leaves of sweet corn infected with MStV from Australia, Costa Rica, Malawi, Mauritius. and the U.S. Leaves of asymptomatic glasshouse-grown sweet corn seedlings were negative controls. In the ELISAs, the OD values at A ₄₀₅ of the Thailand sample with MStV symptoms was 1.00, compared with 0.33 to 1.52 for the positive control samples and 0.00 to 0.02 for fresh or freeze-dried negative controls. The microscopic and serological results indicate the occurrence of MStV in Thailand. References: (1) O. E. Bradfute and J. H. Tsai. Phytopathology 80:715, 1990. (2) R. E. Gingery et al. J. Gen. Virol. 64:1765, 1983.