R&D collaboration with industry - The Japanese sweetpotato story

Sweetpotato (Ipomoea batatas (L.) Lam) is one of the most important upland crops in Japan and attention is currently focused on processing use of this crop. To encourage this type of use, it is necessary to develop utilization systems promoting consumption of sweetpotato and cultivation systems reducing the production cost. Firstly, new technology was developed using chemical components contained in the sweetpotato roots and tops, such as starch, pigments, etc. In relation to starch, a cultivar having low temperature pasting starch was developed. Three kinds of color pigments in the storage roots - anthocyanin, carotenoids and unidentified flavonoids - were revealed to have important physiological functions, such as anti-oxidation, anti-cancer and protection against liver injury. Flour, juice and alcoholic beverages have been developed using colored sweetpotato cultivars. Sweetpotato tops, especially leaves, have an amazing amount of polyphenols composed mainly of chlorogenic acid and its relatives, which have strong physiological functions, in addition to the strong suppressive effects to some food poisoning microorganisms. Secondly, a production system to increase storage root yield was developed, i.e., combining a high yielding cultivar with appropriate application of fertilizer and use of plastic film mulch on planting hills. To reduce the production cost, direct planting of seed roots was shown to be more practical and promising than developing planting machines for seedlings. Finally, sustainable production using some microorganisms, which live in the sweetpotato stems to fix nitrogen in the air (Acetobactor) was reported. These research programs were mostly carried out in collaboration with industry. Japan's success in the development of new sweetpotato usage must depend on collaboration with all the possible sectors related to sweetpotato.