PROBLEM TO BE SOLVED: To obtain the subject new genome containing a base sequence specific to the genome of an Amorphophalus konjak mosaic virus(KMV) or its cDNA, and useful for the control and gene diagnosis of a disease caused by KMV, and the formation of a KMV-resisting breed of a plant, etc. SOLUTION: A new polynucleotide having a nucleotide sequence specific to the genome of an Amorphophalus konjak mosaic virus(KMV) or its cDNA and containing a part or the whole of the nucleotide sequence expressed by the formula. The nucleotide is useful for the control of a disease caused by KMV and a gene diagnosis of KMV, and further for the formation of a KMV- resisting breed of a plant, etc., by introducing it into a plant. The polynucleotide is obtained by collecting leaves of Amorphophalus konjak affected by KMV, separating virus particles by an ordinary method from the leaves, isolating an RNA from the particles, preparing a cDNA library using the RNA, screening the library with a probe consisting of a part of the DNA of KMV and recovering the cDNA from a clone in which a positive signal is detected.
