Construction of Infectious cDNA Clone of a Chrysanthemum stunt viroid Korean Isolate

Abstract

Chrysanthemum stunt viroid (CSVd), a noncoding infectious RNA molecule, causes seriously economic losses of chrysanthemum for 3 or 4 years after its first infection. Monomeric cDNA clones of CSVd isolate SK1 (CSVd-SK1) were constructed in the plasmids pGEM-T easy vector and pUC19 vector. Linear positive-sense transcripts synthesized in vitro from the full-length monomeric cDNA clones of CSVd-SK1 could infect systemically tomato seedlings and chrysanthemum plants, suggesting that the linear CSVd RNA transcribed from the cDNA clones could be replicated as efficiently as circular CSVd in host species. However, direct inoculation of plasmid cDNA clones containing full-length monomeric cDNA of CSVd-SK1 failed to infect tomato and chrysanthemum and linear negative-sense transcripts from the plasmid DNAs were not infectious in the two plant species. The cDNA sequences of progeny viroid in systemically infected tomato and chrysanthemum showed a few substitutions at a specific nucleotide position, but there were no deletions and insertions in the sequences of the CSVd progeny from tomato and chrysanthemum plants.

Sequence variability ofChrysanthemum stunt viroidin different chrysanthemum cultivars

“…Interestingly, the consensus CSVd genome sequences as well as v1 were identical to the previously identified CSVd SK1 genome ( Yoon et al, 2014 ). In addition, v2 and v3 displayed only one nucleotide and three nucleotide substitutions compared with CSVd SK1.…”

Peer Review #2 of "Sequence variability of Chrysanthemum stunt viroid in different chrysanthemum cultivars (v0.1)"

“…The advantage of this phylogenetic tree is that it can show the dominant CSVd variant as well as its sister variants derived from the dominant CSVd variant. For example, among the 24 CSVd variants in Group A, v1 was the dominant CSVd genome, while the other 23 variants were derived from v1.Interestingly, the consensus CSVd genome sequences as well as v1 were identical to the previously identified CSVd SK1 genome(Yoon et al 2014). In addition, v2 and v3 displayed only one nucleotide and three nucleotide substitutions compared with CSVd SK1.…”

“…In this study, we examined genetic variations of the CSVd genome in single chrysanthemum Manuscript to be reviewed construction of an infectious clone for CSVd (Yoon et al 2014). Therefore, the majority of CSVdinfected chrysanthemum plants in this study might be symptomatic, and the potential risk of CSVd in chrysanthemum production in Korea might be very high.…”

Viroid‐derived small RNA induces early flowering in tomato plants by RNA silencing

“…However, it should be noted that tomato plants are annuals and early flowering is not as obvious as in chrysanthemum plants. This is mainly because chrysanthemum plants are perennials and, after 3–4 years of CSVd infection, they flower at least 2 weeks earlier than do healthy plants (Yoon et al, ). As presented in Fig.…”

“…Often, viroid infection induces early flowering in plants, as reported previously in chrysanthemums infected with the chrysanthemum stunt viroid (CSVd) (Hosokawa et al, ). The infection of chrysanthemum by CSVd causes serious economic losses for 3 or 4 years after the initial infection by changing the flowering time, and also causes other symptoms, such as stunting and flower colour bleaching (Yoon et al, ). Infected plants bloom earlier than normal plants of the same cultivar, and this effect increases with time (https://www.eppo.int/QUARANTINE/virus/Chrysanthemum_stunt/CSVD00_ds.pdf).…”