Naslov
Citrus exocortis viroid variants M and S-another case of Dr. Jekyll and Mr. Hyde?

Autori
Škorić, Dijana

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Programme of "Symbiose" / BIUS (Udruga studenata biologije) - Zagreb, 2004, 13-14

Skup
Symbiose, Croatia 2004 (Congress of European biology students)

Mjesto i datum
Zagreb, Hrvatska, 01.08.2004. - 10.08.2004

Vrsta sudjelovanja
Pozvano predavanje

Vrsta recenzije
Nije recenziran

Ključne riječi
citrus exocortis viroid; Gynura aurantiaca; host-pathogen relationships; symptom expression

Sažetak
Viroids are noncoding, circular, single-stranded RNAs of 246-401 nucleotides able to replicate autonomously only in some plant species. These minimal RNA genomes, despite their limited size, can induce serious plant diseases. Although the information concerning the viroid physical and chemical properties is detailed and extensive, the molecular mechanisms of viroid-plant interactions have only recently been dealt with. Citrus exocortis viroid (CEVd) is the oldest known and the most severe viroid of citrus. It is the only one of six citrus viroids that also infects Gynura aurantiaca herbaceous host that often serves as a reservoir plant for CEVd in the greenhouse conditions. An unusal shoot displaying extremely mild symptoms was detected on a CEVd-infected Gynura plant exhibiting the usual severe CEVd-symptoms. The variants CEVd-S and CEVd-M were isolated from tissue displaying severe and mild symptoms, respectively. They differed only in five nucleotides within the viroid pathogenic domain. The variants remained stable when propagated by rooted cuttings or from successive plants inoculated with tissue extracts or transcripts from cDNA clones. CEVd-S consistently induced very severe reaction in Gynura throughout a range of environmental conditions. CEVd-M-induced symptoms varied greatly, from asymptomatic to the severe Gynura reaction when grown at 40°C. This "Dr. Jekyll and Mr. Hyde" host response was confined only to Gynura aurantiaca. The differential response could not be correlated with any changes in sequence or the conformation of the CEVd-M viroid variant, as predicted by molecular modelling. The variable symptom expression induced by the CEVd-M variant seemed to be associated with a specific temperature-sensitive response of Gynura aurantiaca. Other possible mechanisms of differential response for this pathogen-host interaction will also be discussed.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

POVEZANOST RADA