A method of determining the presence or absence of a yam mosaic virus other than YMO6 in a plant of the genus Yamosa resistant to the virulent strain of yam mosaic virus inoculated with the yamo mosaic virus attenuated strain YMO6
<；P>；PROBLEM TO BE SOLVED: To make a new JYMV attenuated strain YMO6 preventing the affection of Japanese yam mosaic virus strong poison strain and enabling the production of stable Japanese yam by a low temperature treatment, and to provide a Japanese yam exhibiting a cross protection against the JYMV strong poison strain from the Japanese yam infected with the YMO6, and to analyze the genome of YMO6 to enable determination of the presence or absence of Japanese yam mosaic virus infection except the YMO6. <；P>；SOLUTION: A plant having Japanese yam mosaic virus attenuated strain YMO6 having a RNA represented by a specific base sequence in a Dioscorea plant, and resistant to Japanese yam mosaic virus strong poison strain can be made. The infection of the resistant plant can be determined by IC-RT-PCR-RFLP-analyzing a mutation in the NIb to CP region of Japanese yam mosaic virus attenuated strain YMO6 gene and using a restriction enzyme HaeIII. <；P>；COPYRIGHT: (C)2010,JPO&INPIT
