Using a competent tissue for efficient transformation of sugarbeet (Beta vulgaris L.)

Transgenic sugar beet tolerant to imidazolinone obtained by Agrobacterium-mediated transformation

“…Transgenic cells had not any unam biguous selective advantages over the non trans genic ones in direct regeneration from the meris tem zones of explants. Selection on kanamycin resulted in production of escapes amounted to 50-95 % among the regenerated kanamycin tol erant shoots [33,34,38,41,44,45]. Similar results were obtained when 15 mg/l phosphinothricin was used for selection after transformation of embryo genic callus of cotyledonary origin [44] or 10 mg/l hygromycin after transformation of bud clumps from immature inflorescence [43].…”

“…Whereas transformation frequen cy depends on efficient and reliable tissue culture regeneration system the early experiments on genetic transformation of sugar beet were mainly focused on the search for the genotypes with high regenerative potential and the explants whose cells were the most competent for regeneration. Such high efficiency regeneration systems for sugar beet are (1) direct regeneration from petioles [32][33][34], cotyledonary node explants [35,36], shoot bases [37,38], bud clumps from immature inflorescence and (2) indirect regeneration via callus from cotyledons and hypocotyls [39,40]. Sugar beet transformation frequency of different explants was reported mainly within 1-5 % [28,35,[39][40][41][42] and arrived at 19.2 % in case of shoot base transforma tion [37,38].…”

Enhanced resistance to a lepidopteran pest in transgenic sugar beet plants expressing synthetic cry1Ab gene

“…Means in each column followed by different letters are significantly different in a Duncan multiple range test at P B 0.01 before (Norouzi et al 2005), using appropriate explant is a critical factor in regeneration of transgenic plants. Here, we have used a combination of methods introduced by Hisano et al (2004) and Norouzi et al (2005) with some modifications to optimize T-DNA delivery and regeneration parameters such as Agrobacterium density, salt composition, antibiotics concentration, and phytohormones composition (data not shown) in media during transformation process based on the influencing factors outlined by Jacq et al (1993) and Opabode (2006). Except for the early stages, we used kanamycin at a constant concentration of 100 mg l -1 for transformant selections.…”

“…Except for the early stages, we used kanamycin at a constant concentration of 100 mg l -1 for transformant selections. Since higher concentration of kanamycin was found to inhibit chlorophyll synthesis even in transgenic shoots (Norouzi et al 2005) and represses the subsequent regeneration of transgenic plants (Ivic-Haymes and Smigocki 2005a), we assume that the high efficiency of our transformation method could be due, at least in part to such a selection strategy. Interestingly, during explant preparation for transformation of genotype 7233, we found many shoots emerged on the leaf blade of some shoots.…”

“…Transformation procedure was done as described previously (Norouzi et al 2005) with some modifications. Media used for transformation are listed in Table 1.…”