植物의 新育種技術

New Plant Breeding Methods

Thanks to the discovery of the principles on heredity, the recognition of the pure-line concept in the early twentieth century, and to the development of various fields of biological and agricultural sciences in later years, the breeeding works could be performed based on firm scientific knowledges, thereby bringing about rapid progress in the breeding science and producing tens of thousands of superior varieties in agricultural crops, ornamental plants, animal husbandry, and even in sericulture in the last five decades. With the years passing and varieties highly improved, however, the conventional breeding practices have met many challenges or difficulties not surmountable by ordinary present-day means: 1) Gene flow is mainly confined to being intervarietal and obtaining the necessary gene sources usable is becoming harder. 2) As the breeding is carried out in the open-field, it is subjected to the climatic conditions. 3) Breeding works require large facilities and manpower, besides needing unusually long duration of years. On the other hands, through the studies on the naked protoplast, development of various methods of genetic manipulations, and recent advancement in genetic engineering techniques, it seems we have approached nearer to the days when we shall be able to transfer or exchange the genes between distantly related species or even between microorganisms and higher forms of life by non-sexual-reproductive means. To explore the possibility of utilizing the genetic materials possessed by the distantly related or unrelated organisms in the improvement of agricultural crops, this paper has dealt with the use of cell population as the breeding materials, the aspect of cell hybrid, introduction of alien genetic materials into naked protoplast by manipulation, the possibility of using nif gene, genetic engineering technique, and other related matters.