Transient Expression of Homologous Hairpin RNA Interferes with Broad bean wilt virus 2 Infection in Nicotiana benthamiana

Abstract

Broad bean wilt virus 2 (BBWV2), genus Fabavirus, subfamily Comovirinae, family Secoviridae, causes damage in many economically important horticultural and ornamental crops. Sequence alignments showed several conserved sequences in 5' non-coding regions (5' NCRs) of RNA 1 and RNA 2 in all BBWV2 strains characterized so far. Based on this observation, we generated a hpRNA construct (pIR-BBWV2) harboring an inverted repeat containing a 210 bp cDNA fragment homologous to 5' NCR portion of BBWV2 RNA 1 to investigate the silencing potential for its ability to interfere with a rapidly replicating BBWV2. Agrobacteriummediated transient expression of the IR-BBWV2 had a detrimental effect on BBWV2 infection, showing no distinct symptoms in non-inoculated leaves of the agroinfiltrated Nicotiana benthamiana plants. BBWV2 genomic RNAs were not detected by RT-PCR from tissues of both the inoculated leaves and upper leaves of the agroinfiltrated plants. Accumulation of virus-derived small interfering RNAs was detected in the inoculated leaf tissues of N. benthamiana plants elicited by transient expression of IR-BBWV2 indicating that RNA silencing is responsible for the resistance to BBWV2.