Partial male sterility in transgenic tobacco carrying an antisense gene for alternative oxidase under the control of a tapetum-specific promoter

The alternative oxidase of plant mitochondria is the terminal oxidase of th e cyanide-insensitive respiratory pathway and is encoded by a nuclear gene. A 1 kb genomic fragment including exon 3 of the alternative oxidase was am plified by PCR from the genome of Arabidopsis thaliana. This fragment was c onnected to a tapetum-specific promoter in the antisense orientation and th en introduced into tobacco. The pollen viability in three transgenic plants ranged from 2% to 60%. The reduced pollen viability cosegregated with the transgene in a selfed progeny. Immunolocalization of alternative oxidase pr otein in the immature flower bud section indicated that expression of alter native oxidase protein in tapetum of the transgenic plant was much lower th an that of the non-transformant. The histological observation and protein g el-blot analysis showed that the development of pollen grains in the transg enic plant did not progress after the degradation of the tapetum, and the a mount of alternative oxidase in pollen grains of the transgenic plant becam e lower than that of the non-transformant. These results suggested that the alternative oxidase activity in the tapetum has a significant effect on th e pollen development.