| Budget Amount *help |
¥2,500,000 (Direct Cost: ¥2,500,000)
Fiscal Year 1992: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1991: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
To develop an efficient method in obtaining transgenic plants of sweet potato, Agrobacterium-mediated transformation and regeneration from calli and leaf disks were carried out. Six sweet potato cultivars and a wild diploid species (I.leucantha), and an A.tumefaciens strain, EHA101 were used. This bacterial strain has a GUS expression vector which contains a kanamycin resistant (npt-II) and a hygromycin resistant (hpt) genes.
Shoot apexes, petioles and stems were excised and coincubated with A.tumefaciens for 20 min. They were transferred to a callus induction medium containing antibiotics. After one or two months, transformed calli expressig a GUS gene were induced, but no plantlet was regenerated from these calli. In the following experiment, an embryogenic callus was induced from a shoot apex with 2,4-D. A high frequency of plant regeneration was observed from this callus. By three days coincubation of the calli with A.tumefaciens, antibiotic resistant calli were obtained and adventitious embryos were formed in some of the calli. However, no plant regeneration was observed from the adventitious embryos.
Plant regeneration system without callus induction was newly developed with leaf disks in two sweet potato cultivars, Jewel and Tainou No.10. Regenerated plants were obtained directly from leaf disks with NAA or obtained by transferring adventitious roots formed from leaf disks onto the medium without hormones. After a coculture with A.tumefaciens for 5 days, transformed roots were regenerated on the medium with antibiotics. However, the growth of these roots stopped in 1 to 2 cm long and no plant was regenerated from these roots.
Further research is needed on the improvement of regeneration frequency from transformed cells and tissues to obtain transgenic plants of sweet potato.
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