Virus-Induced Gene Silencing of Endogenous Genes and Promotion of Flowering in Soybean by Apple latent spherical virus-Based Vectors

Abstract

Soybean, which has been traditional food in Asian countries, is one of the most important crops due to its high quality protein and oil. Various functional components derived from secondary metabolite also have received significant attention in terms of human health. Elucidation of the gene function associated with the biosynthesis of various seed components at molecular level will provide valuable information for improvement of soybean. A great deal of information at the molecular level of soybean, including expression sequence tag (EST) libraries, microarray data, genome sequences, genetic linkage map, comparative genomics, and DNA markers has been reported (Alkharouf et al., 2004; Cheng et al., 2008; Choi et al., 2007; Grant et al., 2010; Haerizadeh et al., 2009; Hecht et al., 2005; Hisano et al., 2007; Nelson and shoemaker., 2006; Schmutz et al., 2010; Shoemaker et al., 2004; Wong et al., 2009; Zhu et al., 2005). This information can provide the candidate gene sequences controlling important traits of soybean, and the functional gene analysis tool for soybean is very important to identify the genes associated with important traits, soybean management, and efficient genetic improvements of soybean. Agrobacteriumand biolistic-mediated technologies have been developed for the introduction of foreign genes into plants (Klein et al., 1987; Zambryski et al., 1983). As another approach, a virus vector-mediated gene delivery system has been developed for several plants. Plant virus vectors could be used for both the expression of the foreign genes and the suppression of the target genes by virus-induced gene silencing (VIGS) in infected plants (Gleba et al., 2004; Purkayastha and Dasgupta., 2009). A virus-mediated gene delivery system is quick and does not require transformation and regeneration techniques, and is widely used for functional gene analysis in plants. Especially, it is an attractive tool for major crop plants including soybean, in which efficient transformation is not established for various cultivars. In soybean, five virus vectors were constructed from Clover yellow vein virus (CIYVV), Soybean mosaic virus (SMV), Bean pod mottle virus (BPMV), Cucumber mosaic virus (CMV), and Apple latent spherical virus (ALSV) (Igarashi et al., 2009; Masuta et al., 2000; Nagamatsu et al., 2007; Wang et al., 2006; Zhang and Ghabiral., 2006). CIYVV and SMV have been developed for foreign gene expression by a fusion polyprotein expression strategy, and BPMVand ALSV-based vectors have been developed for both the expression of foreign genes and VIGS