Insect resistent rice

Modified rice BT63 (TT51-1) is an insect-resistant strain that expresses a codon-optimized, truncated Cry1Ab/Ac fusion cassette derived from sequences of Bacillus thuringiensis subsp. Kurstaki HD1 and HD73. The synthetic construct encodes an insecticidal protein conferring resistance against certain lepidoptera species.

pFHBT1 and pGL2RC7

Expression:
The expression of the hybrid Crystal protein 1Ab/Ac (Cry1Ab/Ac) is under the control of a Oryza sativa (rice) Actin 1 gene promoter and the Agrobacterium tumefaciens nopaline synthase (nos) terminator. The first intron of rice Actin 1 was included with the promoter to promote expression of Cry1Ab/Ac in the rice plant.

Hybrid Cry1Ab/Ac:
The hybrid Cry1Ab/Ac consists of 1344 bp from B. thuringiensis HD1 Cry1Ab and 486 bp from B. thuringiensis HD73 Cry1Ac. The sequence of the hybrid Cry1Ab/Ac was sequence optimized for high G/C content for efficient expression in rice.

Information regarding the transgene insertion:
The transgenic insert contains two tandem repeats of a Cry1Ab/Ac cassette integrated at the same site as a head-to tail concatemer. The first Cry1Ab/Ac cassette at the 5' end of the transgenic insert contains a truncated Actin 1 promoter (149 bp) which is missing the regulatory elements for maximal gene expression and cannot encode for a functional protein.

The second Cry1Ab/Ac cassette is complete. An 83 bp long segment of the Amp gene is located between the two tandem repeats of the Cry1Ab/Ac cassette. Incomplete ampicillin (653 bp) and hygromycin (50 bp) resistance genes are further located in the 3' downstream region.