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A viroid disease causing chlorosis of leaves and dwarfism was found on commercial tomato plants in Hiroshima Prefecture, Japan. Grafting of stems from infected plants onto healthy plants resulted in the same symptoms on the healthy plants. Small RNAs were isolated from infected plant tissue and caused identical symptoms by 3-4 week after mechanical inoculation of tomato seedlings. Nucleotide sequencing indicated that the causal pathogen was Tomato chlorotic dwarf viroid (TCDVd) sharing 98% nucleotide sequence identity with that of a Canadian isolate reported previously. This description is the first of TCDVd infection of tomato plants in Japan.

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The chrysanthemum stunt viroid (CSVd) is a small, single-stranded, infectious RNA forming a circular secondary structure, which belongs to the Pospiviroidae family and mainly infects certain species and cultivars of Compositae and Solanaceae. The effects on cultivated chrysanthemum are severe, including stunting of plant height, reduced flower size, and flower color bleaching. However, the expression of the symptoms depends on the chrysanthemum cultivars. CSVd is known to be readily transmitted by sap, but the infection rate and incubation period were observed to differ according to the varieties. Some CSVd-resistant cultivars have also been reported and the resistance is heritable in crosses between a CSVd-resistant chrysanthemum cultivar and CSVd-susceptible cultivars.

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