DNA content of dormant barley leaf nuclei and the synthesis of RNA and DNA during germination.

The nature of the RNA synthesized during early germination appears to be controversial. In onion [ 1 ] , lettuce [2] , Vicia faba [3] , Phaseolus vulgaris [4] and Triticum vuZgare [ 51 RNA species synthesized include predominantly ribosomal and transfer RNA. In Triticum durum, Chen et al. [6] found no mRNA synthesis during the first 24 hr of germination; synthesis was triggered at a later time. On the other hand, reports on maize [7-lo] suggest that earliest RNA synthesis (occurring between 4 and 8 hr of germination) involves mRNA but not ribosomal and transfer RNA. Similar results were also reported for Triticum aestivum [ 111 where it has been claimed that earliest RNA synthesis involves a discrete mRNA species of mol. wt 1.5 X lo6 daltons. We report here the DNA content in the dormant cell population of an organ of the barley embryo and the synthesis of RNA and DNA during the first 24 hr of germination. During this period the cell population does not change significantly in size since no appreciable cell division activity starts until about 22 hr after germination. The conflicting reports on the nature of the early RNA synthesis led us to consider a possible correlation between the DNA content of the dormant cell population and post dormancy RNA synthesis. A possible basis for such a correlation is discussed.