Somatic embryo,an alternative target tissue for agrobacterium-mediated transformation in Hevea brasiliensis

Traditionally,embryogenic callus has been used as the only receptor source of genetic transformation in h. brasiliensis. in this study,we showed that somatic embryos were a viable alternative to embryogenic callus. the appropriate concentration of both decontamination and selection antibiotics was firstly screened. visual and cytological observations found both epidermal and subepidermal cotyledon cells could be infected,indicating that somatic embryos were susceptible to antibiotics and agrobacterium. subsequently,five isolated consecutive transformation experiments were carried out to produce the transgenic plants using a total of 1158 somatic embryos,of which 47 (4.06 %) gus-positive embryos were produced after cell differentiation and embryogenesis. six were successfully multiplied and produced 33 plants. pcr and southern blot analysis confirmed that the t-dna was integrated into the recovered plants. finally,three additional cycles of secondary embryogenesis were carried out for transgenic embryo proliferation efficiency assessment. the rate of proliferation tended to slightly increase with each proliferation generation,and one initial transgenic embryo-derived gus-negative embryo were observed in the fifth multiplication cycle,indicating that transgenic plants could be propagated through secondary embryogenesis and some initial transgenic embryos might be chimeric. this is the first attempt on producing transgenic plants using somatic embryos as the target tissue in h. brasiliensis. it is demonstrated that somatic embryos can be used as an alternative target tissue for agrobacterium-mediated transformation in hevea brasiliensis. © copyright by the rubber research institute of malaysia all rights reserved.