THE METABOLIC STATUS OF RIBONUCLEIC ACID IN SOYBEAN ROOTS EXPOSED TO SALINE MEDIA

Abstract

The effects of sodium or potassium sulfate on RNA metabolism in soybean roots were examined. Two soybean varieties differing in salt tolerance were used.Growth for 6 days in 50 mM sulfate salts inhibited dry weight production and DNA synthesis in both varieties, the sodium salt being more inhibitory than potassium. Salinity, whether sodium or potassium, nearly stopped protein synthesis and retarded RNA synthesis.Both salts accelerated the endogenous degradation of RNA in root homogenates, sodium being more effective than potassium. Ribosomal RNA was degraded primarily. In the salt-tolerant soybean, total RNA of root tips did not decrease on a DNA basis; only a small decrease occurred in the salt-sensitive variety.Nucleic acids from roots were resolved on methylated albumin columns. Oligonucleotides increased with salinity in both varieties. Sodium sulfate drastically reduced ³²P incorporation into nucleic acids in the salt-sensitive soybean, but less in the tolerant variety. Potassium salinity had little effect on radioactivity incorporation. Incorporation of ³²P into the DNA fraction was reduced more in sodium than in potassium salinity, with the salt-sensitive soybean being affected most.Aberrations in RNA metabolism are discussed in relation to reduced growth in saline media.