RESUMO
To explore a new approach to generating reproductive sterility in transgenic plants, the barnase gene from Bacillus amyloliquefaciens was placed under the control of an 1853-bp nucleotide sequence from the 3'end of the second intron of Arabidopsis AGAMOUS and CaMV 35S (-60) minimal promoter [AG-I-35S (-60)::Barnase], and was introduced into tobacco through transformation mediated by Agrobacterium tumefaciens. All AG-I-35S (-60)::Barnase transgenic plants showed normal vegetative growth and 28% of the transgenic lines displayed complete ablation of flowering. Two transgenic lines, Bar-5 and Bar-15, were 98.1 and 98.4% sterile, respectively, as determined by seed production and germination. When controlled by AG-I-35S (-60) chimeric promoter, barnase mRNA was detected in the reproductive tissues of transgenic tobacco plants, but not in vegetative parts. This study presents the first application of an AG intron sequence in the engineered ablation of sexual reproduction in plants. The AG-I-35S (-60)::Barnase construct can be useful in diminishing pollen and seed formation in plants, providing a novel bisexual sterility strategy for interception of transgene escape and has other potentially commercial use for transgenic engineering.
