Development of genetically modified chrysanthemums resistant to Chrysanthemum stunt viroid using sense and antisense RNAs

Chrysanthemums are one of the most popular flowers. Of known several pathogens causing serious diseases in chrysanthemums, Chrysanthemum stunt viroid (CSVd) is regarded as an important pathogen for chrysanthemums. To control CSVd, it is desirable to generate genetically modified (GM) chrysanthemums resistant to CSVd. In this study, we developed GM chrysanthemum by introducing sense and antisense RNA sequences of CSVd into a commercial chrysanthemum cultivar. A total of 39 GM chrysanthemum lines using four different constructs carrying sense or antisense RNAs were generated by Agrobacterium-mediated transformation. RT-PCR confirmed the expression of introduced RNA sequences in GM and was performed to identify GM lines resistant to CSVd. As a result, nine lines out of 16 tested GM chrysanthemum lines showed very strong resistance against CSVd infection. Phenotype analyses showed that GM plants have grown well as compared to WT plants after CSVd infection. Taken together, this is the first study which develops GM chrysanthemums resistant to CSVd using sense and antisense RNAs of CSVd.