Expression of HBs Ag in tomatoes resulted in abnormal shoot regeneration in vitro

Hbsag m gene-modified tomatoes (lycopersicon esculentum var. cerasifarm) had been constructed by agrobacterium tumefaciens-mediated transformation. we obtained one line (n244) of transgenic mutant. during the in vitro micropropagation of n244,we found abnormal shoot regeneration as to compared with the non-genetically modified tomatoes (control) under ms medium containing 10 μm 6-benzyladenine (ba) and 1.0 μm α-naphthalene acetic acid (naa). histological studies identified two distinct pathways in the regeneration of the hbsag m gene-modified tomato via callus tissues,somatic embryogenesis,and de novo shoot organogenesis,whereas only shoot organogenesis was detected in the non-genetically modified tomatoes (control). however,the bud regeneration frequency and the bud number per leaf explant in the hbsag m gene-modified tomato were same as those in control. furthermore,the abnormal shoot regeneration did not change the stability of hbsag m gene in regenerated plant. flow cytometric analysis suggested that the regenerated transgenic tomato was triploid (n=36) whereas the control plant was the normal diploid (n=24). the change in chromosome number may account for the abnormal in vitro shoot regeneration. the study reveals the effects of gene insertion,and provides insights into the possible variance mechanisms of the hbsag m gene-modified tomato.