An analysis of spontaneous deletion site in RNA2 of a new variant of Soil-borne wheat mosaic virus systemically infects plants at high temperatures.

摘要

Experiments were conducted to analyze the occurrence of deletion mutation in RNA2 of new variants of Soil-borne wheat mosaic virus (SBWMV) Japanese strain-JT isolate, which have the ability of replication and systemic infection of plants at higher temperature of 25 degrees C. Barley plants infected by SBWMV were grown in a growth cabinet of 17 degrees C for 1 month, followed by shifting temperature to 22 degrees C and finally to 25 degrees C, each for 1 month, respectively. New variants emerged with the ability of systemic infection of barley plants at 25 degrees C and spontaneous deletion mutation occurred in RNA2 by retaining same nucleotide positions of 5' and 3' terminal region of RT gene among individual plants. C-terminal region of RT protein which had already been shown to be restored in-frame, was truncated after out-frame deletion of RT gene leading to a stop codon (TGA, nt2497-2499) suggesting that C-terminal region of RT protein is not necessarily translated after deletion of nucleotide positions 867-2445 downstream of the capsid protein gene. The virus maintains 3'-terminal of RT gene due to act as a promoter for transcription of p19 subgenomic RNA, which is required for systemic infection of plants.