Beet necrotic yellow vein virus (BNYVV) and Beet soil-borne mosaic virus (BSBMV) belong to the Benyvirus genus, possess a multipartite genome formed by four ssRNAs(+) and are both transmitted by the plasmodiophorid Polymyxa betae. BSBMV and BNYVV are closely related since they possess the same host range, vector and genome organization. Recent studies demonstrated a possible amplification and transmission of BSBMV RNAs by BNYVV helper strain. In the United States of America, both benyviruses are frequently present in the same cultivated field, infecting the same plant but no chimeric forms have been described from field isolates so far. The possibility that BNYVV/BSBMV chimeras may be generated has been investigated. Chenopodium quinoa local infection has been carried out using in vitro infectious transcripts of BNYVV and BSBMV RNA-1 and -2 and the behavior of BSBMV/BNYVV chimeras and wild type isolates has been compared. The chimera BoStras12 (BSBMV RNA-1 + BNYVV RNA-2) induced severe necrotic lesions on the leaves, probably due to a hypersensitive response of the plant, in contrast to the typical chlorotic lesions of wild type combinations. The necrosis disappeared when the plant was co-inoculated with BoStras12 together with a viral replicon expressing BSBMV p14, a cysteine-rich protein acting as a suppressor of post-transcriptional gene silencing. Thus, properties of Benyvirus p14s have been investigated. P14s have a zinc-finger domain able to bind nucleic acids and agroinfection of Nicotiana benthamiana plants demonstrated that these proteins are able to suppress the PTGS downstream of the Dicer proteins, without interfering with the transitivity. Moreover, both p14s are localized in the nucleolus, forms homodimers and binds the “coremin” sequence, a stretch of 20 nucleotides present in the RNA-3 of Benyviruses and necessary for the systemic spread of viruses in the plant. Experiments performed to investigate relationships between BSBMV/BNYVV p14s and VSR activity, “coremin” sequence, long distance movement and absence of natural chimeras of Benyviruses will be presented.
Benyvirus chimeras evidence that silencing suppressor proteins specifically interact with viral RNAs / Delbianco, A.; Dall’Ara, M.; Flobinus, A.; Hleibieh, K.; Klein, E.; Rubies Autonell, C.; Gilmer, D.; Ratti, C.. - STAMPA. - (2013), pp. 17-17. (Intervento presentato al convegno International Advances in Plant Virology Meeting tenutosi a Norwich, UK nel 25 - 27 Settembre 2013).
Benyvirus chimeras evidence that silencing suppressor proteins specifically interact with viral RNAs
DALL'ARA, MATTIA;RATTI, CLAUDIO
2013
Abstract
Beet necrotic yellow vein virus (BNYVV) and Beet soil-borne mosaic virus (BSBMV) belong to the Benyvirus genus, possess a multipartite genome formed by four ssRNAs(+) and are both transmitted by the plasmodiophorid Polymyxa betae. BSBMV and BNYVV are closely related since they possess the same host range, vector and genome organization. Recent studies demonstrated a possible amplification and transmission of BSBMV RNAs by BNYVV helper strain. In the United States of America, both benyviruses are frequently present in the same cultivated field, infecting the same plant but no chimeric forms have been described from field isolates so far. The possibility that BNYVV/BSBMV chimeras may be generated has been investigated. Chenopodium quinoa local infection has been carried out using in vitro infectious transcripts of BNYVV and BSBMV RNA-1 and -2 and the behavior of BSBMV/BNYVV chimeras and wild type isolates has been compared. The chimera BoStras12 (BSBMV RNA-1 + BNYVV RNA-2) induced severe necrotic lesions on the leaves, probably due to a hypersensitive response of the plant, in contrast to the typical chlorotic lesions of wild type combinations. The necrosis disappeared when the plant was co-inoculated with BoStras12 together with a viral replicon expressing BSBMV p14, a cysteine-rich protein acting as a suppressor of post-transcriptional gene silencing. Thus, properties of Benyvirus p14s have been investigated. P14s have a zinc-finger domain able to bind nucleic acids and agroinfection of Nicotiana benthamiana plants demonstrated that these proteins are able to suppress the PTGS downstream of the Dicer proteins, without interfering with the transitivity. Moreover, both p14s are localized in the nucleolus, forms homodimers and binds the “coremin” sequence, a stretch of 20 nucleotides present in the RNA-3 of Benyviruses and necessary for the systemic spread of viruses in the plant. Experiments performed to investigate relationships between BSBMV/BNYVV p14s and VSR activity, “coremin” sequence, long distance movement and absence of natural chimeras of Benyviruses will be presented.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
