Refined Factors in Multi-needle-assisted Transformation of Soybean

Previous studies have improved Agrobacterium-mediated soybean [Glycine max (L.) Merrill] cotyledonary node method by the development of a simple multi-needle-assisted wounding method using cotyledonary node cells of 1-day-old half seeds as target tissue. The goal of this study was to investigate the factors affecting the efficiency of the multi-needle-assisted transformation of soybean cotyledonary node cells (MNAT). The factors were studied by the GUS activity using a binary vector pCAMBIA1301 containing both a gus-intron gene and a hpt (hygromycin phosphotransferase) selectable marker. All of the factors affecting the transformation efficiency were determined after the 1-day-old half seeds punctured 2 times with the multi-needle. The transformation efficiency based on transient expression of the gus gene was significantly affected by the concentration of antioxidants, density of Agrobacterium suspension, infection time and the concentration of acetosyringone (AS). The frequency of the transformed cotyledonary node cells was also affected by soybean genotypes.