Soybean Mosaic Virus Resistance in Transgenic Soybean Caused by Post-transcriptional Gene Silencing

Abstract

Somatic embryos of Glycine max (L.) Merrill cultivar 'Jack' were co-transformed with the coat protein (CP) gene of attenuated isolates of Soybean mosaic virus (SMV) and hygromycin phosphotransferase gene by microprojectile bombardment. CP gene was detected in eleven transgenic plants, and three independent lines highly resistant to SMV were obtained in a previous study. One of these lines, line No. 55, which was assumed to have acquired RNA-mediated resistance, was selected for further gene expression analysis of T 4 and T 5 plants in relation to their viral resistance. The resistant plants contained a lower level of transgenederived RNA than the susceptible ones. On the other hand, based on RNA analysis after mechanical inoculation, SMV-specific RNAs were detected faintly in the resistant plants, while large amounts of RNAs were found in the susceptible ones. During the development of the resistant lines, SMV CP sequence-specific small interfering RNAs (siRNAs) appeared initially in the leaves of the first leaf stage but not in those of the primary stage, and were detected thereafter in the leaves of later stages constantly. The presence of the siRNAs before SMV inoculation was strongly correlated with the resistant phenotype of the lines tested.

RNAi-mediated resistance to SMV and BYMV in transgenic tobacco

“…The approach of creating the RNAi structure from the viral CP gene was mentioned by Furutani et al (2007) as an effective method to improve SMV resistance in soybean. However, in reality, soybean plants can be infected with multiple viruses simultaneously; thus, it is important to construct a transgene that can prevent both viruses causing mosaic disease.…”

“…In 2007, using the RNAi approach, Bonfim et al obtained a transgenic soybean line with high resistance to Bean golden mosaic virus (up to 93%). Another study (Furutani et al 2007) also tried to improve SMV resistance in soybean using genetic engineering techniques.…”

Virus-induced gene silencing in soybean seeds and the emergence stage of soybean plants with Apple latent spherical virus vectors

“…Furthermore, long time (more than 1 year) is needed to obtain transformed soybeans (Furutani 2007;Tougou 2009). Several reports also showed that co-suppression by overexpression of a transgene were reset during the reproduction in several transgenic plants, including soybean plants (Aida and Shibata 1998;Furutani et al 2007;Mitsuhara et al 2002;Yamagishi et al 2006b). Thus, co-suppression by transgene overexpression may not be used for functional analysis of the genes expressed in seed development and early growth stages.…”

Molecular analysis of transgenic melon plants showing virus resistance conferred by direct repeat of movement gene of Cucumber green mottle mosaic virus

“…Consequently, the transgenic plants in which a virus-derived sequence is silenced can be resistant to virus infections (English et al 1997). The higher degrees of resistance correlate to lower levels of accumulation of transgenic transcripts and higher levels of siRNA products (Furutani et al 2007;Wu et al 2009). The expression of siRNA is a hallmark of the activated RNA silencing process (Hamilton and Baulcombe 1999).…”