The aim of the research described is to develop transformed plant varieties with enhanced freezing tolerance through the expression of antifreeze proteins that inhibit ice crystal growth. We have shown that tobacco and tomato plants transformed with a winter flounder antifreeze gene express high levels of the corresponding mRNA. Furthermore, the gene was modified so that the encoded protein is larger and more readily detected. In plants containing this fusion protein, antifreeze expression was observed at the RNA, protein and activity level, with transcriptional levels predominating. We will now evaluate the impact of antifreeze protein on the freezing tolerance properties of fruit from transgenic plants as well as from nontransgenic fruits that have been infiltrated with antifreeze protein. If necessary, we will optimize the protein concentration in plant tissue by enhancing protein activity, protein stability, transcription, and translatability. Constructions resulting in optimal freezing tolerance will be transferred into appropriate commercial varieties.***//
