Abstract Soybean mosaic virus (SMV) and bean yellow mosaic virus (BYMV) are two typical types of viruses that cause mosaic in soybean plants. Multiple viral infections at the same site can lead to 66% to 80% yield reduction. We have aimed to improve SMV and BYMV resistance in Vietnamese soybeans using gene transfer techniques under the mechanism of RNAi. In this study, we present newly generated transgenic tobacco plants carrying RNAi [CPi (SMV-BYMV)] resistance to the two types of viruses; 73.08% of transgenic tobacco lines proved to be fully resistant to SMV and BYMV. In addition, the number of virus copies in transgenic tobacco plants was reduced on average by more than 51% compared to the control plants (wild type). This promising result shows the potential of transerring the CPi (SMV-BYMV) structure in soybean to increase resistance of soybean to SMV and BYMV and advance the aims of antiviral soybean breeding in Vietnam.

ABSTRACTThis work studied the amplification, cloning and determination of the GmDREB2 gene from the soybean cultivar DT2008 and five Vietnamese local soybean cultivars (DT26, DT51, DVN5, CB, CBD) and designed the vector carrying the structure containing GmDREB2 gene from cultivar DT2008 (best drought tolerant). The coding region of GmDREB2 gene isolated from six soybean cultivars was 480 nucleotides in length, encoding 159 amino acids. The recombinant structure was designed as 35S- GmDREB2- c-myc and its expression was analysed in transgenic tobacco plants. Recombinant DREB2 protein was expressed in five transgenic tobacco lines with molecular weights close to 20 kDa. During the drought conditions, the proline accumulation of the transgenic tobacco lines was higher than on wild-type (WT) plants, with the rate from 211.17 to 332.44% after five days of drought stress, and from 262.79 to 466.04% after nine days of drought stress. The two lines, TG2 and TG12 had the highest increase rate. These results provided the basis to generate drought-tolerant soybean plants by GmDREB2 overexpression.