GENE ACTION DURING CELLULAR DIFFERENTIATION AND RELATED ORGANOGENESIS IN CROPS CULTURED,IN VITRO

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By using in vitro tuberization system of potato, the accumulation of potato kunitz type proteinase inhibitor (PKPI) mRNA was specifically detected in tubers during the early stage of development, and thus expected to be a molecular marker of potato tuberization. Furthermore, the accumulation of PKPI-mRNA was also found when tissues were treated with cool to warm atmosphere by ascending temperature, and by addition of jasmonic acid.The novel proteins (14,18.5,24.5,45kDa) were induced by ABA in long-term cultured callus of rice and disappeared after plentlet regeneration, while proteins of the same molecular weight existed in intact mature seed embryos and disappeared when the seeds were germinating. Sustaining of embryogenic callus cultures could be some extent achieved by the addition of ABA in medium. This hormone could be responsible for regenerating somatic embryos and for normal embryogeny in rice plants.A protocpl of the trangent gene expression in electroporated protoplasts has been developed for the introduction of foreign DNA into cells from cultured potato, tobacco, carrot, and rice. The method yields high amounts of the reporter enzyme B-glucuronidase (GUS) when cognate genes are driven by the promotors of NOS and 35S,and by upstream sequences of PKPI from potato tuber and Actin-1 from rice actin genes. Comparisons with expression in potato, tobacco, carrot, and rice cells indicate that trangent assays can be used to investigate promotor acivation and enhancer function.