Nucleic Acids and Protein Metabolic Changes During Germination of Cotton Seed

Abstract

Summary Gibberellic acid (GA 3 ) treatments of cotton seeds induced the synthesis of RNA, DNA and protein in the embryonic axis during the period of germination. In cotyledons of the same GA 3 -pretreated seeds, the RNA content was lower than in the controls, while the DNA content was increased at the beginning of germination. However, GA 3 treatments did not affect the content of cotyledonary protein. Indole acetic acid (IAA) at low concentration of 10 mg · l -1 resulted in a slight increase in the amount of RNA, DNA and protein synthesized in the axis, while at the higher concentrations of 50 and 100 mg · l -1 the RNA, DNA and protein synthesis were inhibited. In cotyledons, the RNA content was markedly higher than in the control during the first 48 h of germination when IAA was applied at 10 mg · l -1 . Also, the rate of protein depletion from the cotyledons decreased with increasing IAA concentrations, while the content of cotyledonary DNA was not significantly affected by IAA treatments. Coumarin at the lowest concentration used (1 mg · l -1 ) induced the synthesis of RNA, DNA and protein in the embryonic axis, but increasing the concentration of coumarin to 100 mg · l -1 resulted in a reverse effect of inhibition during the period of germination. In cotyledons, a high concentration of coumarin markedly decreased the rate of RNA and protein degradation during the germination period.