THE DECREASE IN POLYAMINE LEVELS IS NOT ASSOCIATED WITH GROWTH-INHIBITION IN SUSPENSION-CULTURED RICE CELLS UNDER NITROGEN DEFICIENCY

The effects of nitrogen deficiency on the growth and polyamine levels of suspension-cultured rice cells were investigated. Nitrogen deficien cy markedly inhibited cell growth and resulted in lower levels of putr escine, spermidine and spermine than in the control culture supplied w ith nitrogen. The growth inhibition of rice cells induced by nitrogen deficiency could be recovered by the addition of a mixture of amino ac ids (glycine, L-aspartic acid, L-glutamic acid and L-arginine), but no t by polyamines (putrescine, spermidine or spermine). Our results indi cate that the decline of polyamine levels is not a factor causing grow th inhibition of suspension-cultured rice cells under nitrogen deficie ncy.