Survey and detection of virus and viroid diseases from chrysanthemum in Thailand

I am Salit Supakitthanakorn, a Ph.D. candidate from the Division of Plant Pathology, Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Thailand, under the supervision of Asst. Prof. Dr. On-Uma Ruangwong. My current research is working on the diagnosis and development of molecular techniques for detection of virus and viroid diseases in chrysanthemum. In Thailand, chrysanthemum plants (Chrysanthemum × morifolium) have been cultivated for many decades. The main cultivation areas are in the northern region. However, notwithstanding that chrysanthemum plants are widely grown, data on virus and viroid diseases are absent. In 2019, our laboratory surveyed chrysanthemum fields and found virus- and viroid-like symptoms on chrysanthemum leaves along with vector insects of plant viruses. Therefore, we decided to examine and identify disease-causing viruses and viroids in chrysanthemum. From the literature, we found approximately 10 viruses and 2 viroids that infect chrysanthemum including: Chrysanthemum virus B (CVB), Cucumber mosaic virus (CMV), Chrysanthemum stem necrosis virus (CSNV), Impatiens necrotic spot virus (INSV), Tobacco mosaic virus (TMV), Tomato aspermy virus (TAV), Tomato spotted wilt virus (TSWV), Turnip mosaic virus (TuMV), Zucchini yellow mosaic virus (ZYMV), Chrysanthemum chlorotic mottle viroid (CChMVd) and Chrysanthemum stunt viroid (CSVd). These viruses and viroids were detected using RT-PCR. Moreover, triple-antibody sandwich (TAS)-ELISA was used to detect the DNA virus, Tomato yellow leaf curl New Delhi virus (ToLCNDV), using the monoclonal antibody. The results of our virus and viroid detection from 223 chrysanthemum samples revealed three viruses (CVB, TMV and TuMV) and two viroids (CChMVd and CSVd). The nucleotide sequences of the detected viruses and viroids were analyzed. We confirmed the sequences with isolates deposited in GenBank. Among the detected pathogens, CVB had the highest incidence. Furthermore, according to our results, the incidence of virus and viroid diseases in chrysanthemum of Thailand was lower by 10% compared to that reported in literature. Moreover, viral particles were observed under transmission electron microscope (TEM) and found that CVB had flexuous rod particles; TMV had rigid rod particles; and TuMV had filamentous particles. This study provides viral detection results along with associated symptoms observed on chrysanthemum cultivated in northern Thailand. To our knowledge, this is the first detection of virus and viroid diseases from chrysanthemum in Thailand.

Salit Supakitthanakorn won the ISHS Young Minds Award for the best oral presentation at the XV International Symposium on Virus Diseases of Ornamental Plants, which was held virtually in USA and Singapore in December 2021.

Salit Supakitthanakorn, Division of Plant Pathology, Department of Entomology and Plant Pathology, Faculty of Agriculture, Chiang Mai University, Chiang Mai 50200, Thailand, e-mail: salit.supakitthanakorn@gmail.com

The article is available in Chronica Horticulturae