TRANSFER AND TRANSCRIPTIONAL EXPRESSION OF COLEOPTERAN CRYIIIB ENDOTOXIN GENE OF BACILLUS-THURINGIENSIS IN EGGPLANT

Three constructs of a coleopteran toxic cryIIIB Bacillus thuringiensis gene were engineered and incorporated into eggplant (Solanum melongena L.). Southern blot analysis of the eight primary transformants and segregational analysis of their R(1) progenies indicated that the chimeric cryIIIB constructs in each of the transgenic plants were stably incorporated at a single locus or at multiple sites within the same linkage group and that they were regularly transmissible to the progeny. The results of Northern blot and RNase protection analyses demonstrated that transcription of the cryIIIB mRNA takes place in plant cells, but only a small amount of the expected entire length transcripts were produced, The amount; of the 5' end mRNA fragment produced was at least 30 to 40 times more abundant than the amount of the 3' end mRNA fragment, This could be interpreted to mean that either the two ends of the mRNA are of different stability or that the transcription process is often interrupted and only a few mRNAs complete the entire process to the end. When the transgenic plant mRNA was reverse-transcribed, amplified by polymerase chain reaction, and hybridized to the cryIIIB probe, two smaller molecular weight mRNA species were identified. Thus, the preponderance of the cryIIIB mRNA in transgenic plants exists as a truncated species, a situation similar to that of cryI genes when expressed in transgenic plants. Seedlings from the eight independent transgenic plants were tested for Coleopteran insect resistance. However, they did not demonstrate any significant resistance to the first and second instar larvae of the Colorado potato beetle (Leptinotarsa decemlineata Say).