Targeting specific genes for RNA interference is crucial to the development of strong resistance to Rice stripe virus

Abstract

SummaryRice stripe virus (RSV) has a serious negative effect on rice production in temperate regions of East Asia. Focusing on the putative importance of the selection of target sequences for RNA interference (RNAi), we analysed the effects of potential target sequences in each of the coding genes in the RSV genome, using transgenic rice plants that expressed a set of inverted-repeat (IR) constructs. The reactions of inoculated transgenic T 1 plants to RSV were divided subjectively into three classes, namely highly resistant, moderately resistant and lacking enhanced resistance to RSV, even though plants that harboured any constructs accumulated transgene-specific siRNAs prior to inoculation with RSV. Transgenic plants that harboured IR constructs specific for the gene for pC3, which encodes nucleocapsid protein, and for pC4, which encodes a viral movement protein, were immune to infection by RSV and were more resistant to infection than the natural resistant cultivars that have been used to control the disease in the field. By contrast, the IR construct specific for the gene for pC2, which encodes a glycoprotein of unknown function, and for p4, which encodes a major non-structural protein of unknown function, did not result in resistance. Our results indicate that not all RNAi constructs against viral RNAs are equally effective in preventing RSV infection and that it is important to identify the viral 'Achilles heel' for RNAi attack in the engineering of plants.

Suppression of NS3 and MP Is Important for the Stable Inheritance of RNAi-Mediated Rice Stripe Virus (RSV) Resistance Obtained by Targeting the Fully Complementary RSV-CP Gene

“…While previous studies have reported the used of RSV CP and SP sequences in single transgene constructs (Ma et al, 2011;Shimizu et al, 2010), the RNAi effectiveness was quite different. For instance, RNAi transgenic rice plants harboring pSP-specific sequences did not exhibit enhanced RSV resistance (Shimizu at al., 2010).…”

“…For instance, not all RNAi constructs that target viral RNAs are equally effective in preventing RSV infection. Shimizu et al (2010) reported that nearly 90% of the dsRNAi-trigger p4 (SP) transgenic plants were susceptible to RSV infection. Upon considering these results, it is suggested that down-regulation of SP expression appears to be insufficient for the suppression of viral gene expression related to RSV proliferation.…”

“…For instance, RNAi transgenic rice plants harboring pSP-specific sequences did not exhibit enhanced RSV resistance (Shimizu at al., 2010). However, CP/SP double targeting RNAi lines showed stronger RSV resistance than CP or SP single targeting RNAi lines (Ma et al, 2011).…”

Application of Virus-Derived Small Interfering RNAs (vsiRNAs) in Rice Viruses with Insect Vectors, Especially <em>Rice Grassy Stunt Virus</em>

“…Identification of [85,86] stranded RNAs (dsRNAs), which are labeled as S1to S10, as they occur in the electrophoretic pattern of migration on polyacrylamide gels like SDS.…”

Strategic RNA Silencing for Plant Viral Resistance

“…In one study, eight different genes of PVY were targeted and the percentage of resistant plants obtained ranged from 33 % to 64 % (Chen et al 2010). Not all invert repeat constructs targeting different genes of the Rice stripe virus (RSV) were equally effective in preventing RSV infection (Shimizu et al 2011). It is essential to target the viral gene that plays an important role in viral proliferation.…”