Einfluß von N‐Lignin auf Wachstum und N‐Stoffwechsel von Weizen‐Zellsuspensionskulturen

The effects of N‐Lignin on growth and N‐metabolism in wheat cells in suspension cultures N‐Lignin is an organic N‐fertilizer which is synthesized from waste liquors of the pulp industry by oxydative ammonisation. Nearly 40% of its N‐content is available as ammonium, the rest is linked in organic compounds. Water‐soluble fractions of N‐Lignin were added to the nutrient solutions of wheat cells in suspension cultures in order to study the effects on growth and N‐metabolism. The experiments show that N‐Lignin is a suitable nitrogen source for growing wheat cells. The best growth was achieved when 50% of the total nitrogen content of the medium were added as N‐Lignin nitrogen. This mixture of N‐Lignin and nitrate was even superior to the standard B‐5‐medium with respect to the final dry weight. However, higher concentrations of N‐Lignin inhibited cell growth. The effect of N‐Lignin on cell growth is not only influenced by ammonia. If wheat cells were grown on media with ammonium‐N as the sole nitrogen source acids of the citrate cycle had to be added to support growth. This was not necessary with N‐Lignin. N‐Lignin therefore seems to effect the energy metabolism. High amounts of ammonium‐N or the reduced N‐fractions of N‐Lignin respectively resulted in an increase of certain amino acids and especially of the two amides glutamine and asparagine. Furthermore root formation was observed with cells grown in media containing N‐Lignin or ammonium‐N. The root formation seemed to be correlated with added amounts of reduced nitrogen. Root formation was not observed with cell cultures incubated with N‐Lignin solutions which were made free of ammonium‐ions with a cation exchanger (Amberlite IR‐120) loadad with potassium. This indicates that the differentiation of roots in the normally embryonic cells is due to the ammonium‐N content of N‐Lignin. A possible correlation between the content of glutamine and asparagine and the formation of roots is discussed.