Ribosomal and Transfer RNA Synthesis

In rye embryos maturation of rRNA appears to occur much faster, the pattern of synthesis being [112]  

It should be noted here that there are various claims in the literature that ribosomal, or even total, RNA synthesis commences only several or many hours after the beginning of imbibition of dry seeds. These reports should be treated with caution, however, for in many instances the techniques used 

Synthesis of RNA during early imbibition necessitates the presence of an active RNA polymerase. Both dry wheat [64] and rye [46] embryos are rich sources of DNA-dependent RNA polymerases, and these enzymes appear to be available in sufficient quantities to catalyse RNA synthesis immediately upon imbibition. In fact, RNA polymerase activity in imbibing, isolated wheat embryos even declines after the second hour from the start of imbibition [84]. This might not be a characteristic of the intact embryo, however, for in intact wheat grains RNA polymerase activity increases after germination [85]. Whether this increase is in the growing embryo (seedling) or in the aleurone layer has not been determined. 

There is a sufficient supply of tRNAs and their aminoacylating enzymes present in the supernatant of dry seeds to support in vitro protein synthesis 

Source of DNA % DNA hybridized 1.3xl0 rRNA 0.70x10 rRNA 

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Protein and Nucleic Acid Synthesis 159 5.2.4. Ribosomal and Transfer RNA Synthesis... 

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