Electroporation of small RNAs into plant protoplasts: mitochondrial uptake of transfer RNAs.

To study tRNA import into plant mitochondria, we have set up a system to follow the fate in vivo of tRNA transcripts introduced into plant protoplasts by electroporation. Conditions were optimized for maximum tRNA uptake into potato protoplasts. We have shown that in vitro synthesized tRNA transcripts are poor substrates due to rapid degradation leading to low efficiencies of transfer and short life in protoplasts. Labelled natural tRNAs were more efficiently electroporated into protoplasts and they remained stable during protoplast culture. We have observed import into mitochondria of total and purified cytosolic tRNAs in protoplasts but the process was not specific for the tRNA species which are normally imported.