Abstract

The nitrogen metabolism associated with pollen germination in Crinum asiatica var. sinicum Bak. Was studied. A synthetic plant growth stimulant, EDNA (N. N'-dinitroethylediamide), was added to the culture medium in order to detect whether or not this chemical can effect pollen germination and nitrogen metabolism during pollen germination and pollen elongation. In the 180 minute experimental period, the amino acid content in germinating pollen increased about 52% and a remarkable amount of amino acids were released into the culture medium. The protein content of ungerminated pollen contained 18.3% of dry weight, and increased to its maximum quantites in 15 minutes after imbibition in the culture medium, and then decreased gradually. Using 14C-leucine as a tracer to study protein synthesis, we found about 50% of total newly synthesized protein occurred in the first 30 minutes of the germinating period. The RNA content in germinating pollen increased steadily for 150 minutes germinating period, and then maintained at the same level. EDNA at the 2.5 ppm can stimulate the pollen tube elongation, but when its concentration was 10 ppm or higher in the culture medium, a strong inhibited effect on pollen germination and pollen tube elongation was observed. At this optimal concentration of EDNA (2.5-5 ppm), 14C-leucine incorporation into protein was also stimulated. But beyond this concentration, the higher the concentration of EDNA present in the culture, the stronger was the inhibition effect on protein synthesis. From the 14C-uridine incorporation studies, EDNA did not stimulate the RNA synthesis. Although the inhibition mechanism of EDNA on pollen germination and pollen tube elongation are not clear, yet EDNA can inhibit protein synthesis which may be the important effect of this chemical on pollen germination and pollen tube elongation.