Challenging Road to Seed Propagation of Sweet Potato (Ipomoea batatas (L.) Lam): A Case Study in Direct Gene Transformation System to Seeds of Sweet Potato Using Electroporation Method

Apomixis bypasses meiosis to produce seed. And it is considered to bring economic benefits over
than the “Green Revolution” by using to fixation of F1 variety in agriculture. In our laboratory, we have
been successful in cloning the apomixis-specific gene of ASG-1, isolated from Panicum maximum. In
order to do functional analysis of the ASG-1, we have been carrying out the gene transformation of
ASG-1 in sweet potato, a vegetative reproductive crop. In this study, the purpose is getting
transformants by using the seeds of sweet potato and the instrument of NEP21, an electroporation.
As the first step, we used the Ipomoea nil cv. [Kitachiasagao] as stock and Ipomoea batatas (L.) cv.
[Koganesengan], [Narutokintoki] and [Beniazuma] as graft to get seeds. And then, the transformants
of GUS was induced into sweet potato seeds by using the instrument of NEP21. As the results, 1)
according to the standard of selecting variety based on the cross incompatibility referred from Kyushu-
Okinawa Agricultural Research Center, we selected 3 varieties out from 6 ones held; 2) according to
the standard of selection suitable to be used as either seed side or pollen side, we have gotten
matured seeds successfully from the 3 varieties; 3) using the sweet potato seeds collected and the
instrument of NEP21, GUS gene expression was detected in the transformant by GUS dyeing with
blue color appeared on the surface of the seeds and young buds.