GENE ACTION DURING REDIFFERENTIATION AND EMBRYOGENlC DEVELOPMENT IN CROPS CELLS CULTURED, IN VITRO

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By using in vitro system of rice, bentgrass, carrot and potato, the accumulation of knowledge in redifferentiation and embryogenic callus cultures has been commenced. The physiological process of specifical gene activation was observed by the RT-PCR differential displays for somatic embryogenesis of rice, carrot and for dormant bud formation of bentgrass cultures. The role of ABA was found to be important for the induction of embryogenic callus formation in rice and carrot, and of dormant bud formation in bentgrass. On this line of research, the gene expression of peroxiredoxin (Per1) , dehydrin (DH-a18) and viviparous1 (VP1) occurred in cultured cells during the induction of ABA regime.The mRNAs of Per1, DHa18 and VP1 were induced by ABA in the long-term cultured callus of rice and dormant tissue of bentgrass cultures but disappeared after plentlet regeneration, or sprouting. While the transcripts existed in intact mature seed embryoes and disappeared when the seeds were germinating. Sustaining of the embryogenic callus cultures could be some extent achieved by the addition of ABA in medium. This hormone could be responsible for regenerating somatic embryoes and for normal embryogeny in rice plants.Eukaryotic translation initiation factor 5A(eIF-5A) is one of factors necessary for the initiation of eukaryotic cellular protein biosynthesis. Little is known in plant eIF-5A. We have isolated a cDNA encoding SteIF-5A. Five cDNA were cloned from potato showing differential expression, mainly developing tuber and fruit. This suggests that the expression is the highest in metabolic active cell.To protect cellular integrity against damage caused by reactive oxygen and free radicals, plants possess an array of antioxidant systems. Peroxiredoxins are one of enzymatic antioxidants, the functions of which are the most resposible for abiotic stresses upon redifferentiation of crop cells.