title: Digestion of chrysanthemum stunt viroid by leaf extracts of Capsicum chinense indicates strong RNA-digesting activity.
abstract: CSVd could not infect Nicotiana benthamiana when the plants were pretreated with crude leaf extract of Capsicum chinense 'Sy-2'. C. chinense leaves were revealed to contain strong RNA-digesting activity. Several studies have identified active antiviral and antiviroid agents in plants. Capsicum plants are known to contain antiviral agents, but the mechanism of their activity has not been determined. We aimed to elucidate the mechanism of Capsicum extract's antiviroid activity. Chrysanthemum stunt viroid (CSVd) was inoculated into Nicotiana benthamiana plants before or after treating the plants with a leaf extract of Capsicum chinense 'Sy-2'. CSVd infection was determined using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) 3 weeks after inoculation. When Capsicum extract was sprayed or painted onto N. benthamiana before inoculation, it was effective in preventing infection by CSVd. To evaluate CSVd digestion activity in leaf extracts, CSVd was mixed with leaf extracts of Mirabilis, Phytolacca, Pelargonium and Capsicum. CSVd-digesting activities were examined by quantifying undigested CSVd using qRT-PCR, and RNA gel blotting permitted visualization of the digested CSVd. Only Capsicum leaf extract digested CSVd, and in the Capsicum treatment, small digested CSVd products were detected by RNA gel blot analysis. When the digesting experiment was performed for various cultivars and species of Capsicum, only cultivars of C. chinense showed strong CSVd-digesting activity. Our observations indicated that Capsicum extract contains strong RNA-digesting activity, leading to the conclusion that this activity is the main mechanism for protection from infection by CSVd through spraying or painting before inoculation. To our knowledge, this is the first report of a strong RNA-digesting activity by a plant extract.
authors.affiliation: Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan.
authors.forename: Boubourakas
authors.initials: B
authors.lastname: Iraklis
authors.affiliation: Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan.
authors.forename: Hiroko
authors.initials: H
authors.lastname: Kanda
authors.affiliation: Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Nabeshima
authors.affiliation: Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan.
authors.forename: Mayu
authors.initials: M
authors.lastname: Onda
authors.affiliation: Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan.
authors.forename: Nao
authors.initials: N
authors.lastname: Ota
authors.affiliation: Faculty of Agriculture, Kinki University, Nara, Nara, 631-8505, Japan.
authors.forename: Sota
authors.initials: S
authors.lastname: Koeda
authors.affiliation: Graduate School of Agriculture, Kyoto University, Sakyo-ku, Kyoto, Japan. mune@kais.kyoto-u.ac.jp.
authors.forename: Munetaka
authors.initials: M
authors.lastname: Hosokawa
mesh_terms: D002212:Capsicum / Q000737:chemistry*; D031202:Chrysanthemum / Q000821:virology*; D005612:Freeze Drying; D006863:Hydrogen-Ion Concentration; D009928:Organ Specificity / Q000187:drug effects; D010935:Plant Diseases / Q000821:virology*; D010936:Plant Extracts / Q000378:metabolism*; D018515:Plant Leaves / Q000737:chemistry*; D012313:RNA / Q000378:metabolism*; D060888:Real-Time Polymerase Chain Reaction; D013696:Temperature; D014026:Nicotiana / Q000187:drug effects / Q000821:virology; D014772:Viroids / Q000187:drug effects / Q000502:physiology*
chemical_list: D010936:Plant Extracts; D012313:RNA
keywords: Antiviroid agent; Capsicum chinense; Chrysanthemum stunt viroid (CSVd); Leaf extract; RNA-digesting activity