Скачать или смотреть Barnase-Barstar Transgenic Genetic Male Sterility/Pollination Control

Transgenic Genetic Male Sterility (TYGMS).
A gene introduced into the genome of an organism by recombinant DNA technology or genetic engineering is called transgene. Many transgenes
have been shown to produce genetic male sterility, which is dominant to fertility. In such cases, it would be essential to develop effective fertility restoration systems for their use in hybrid seed production. Barnase/Barstar system is a good example of transgenic male sterility. The Barnase gene of Bacillus amyloliquefaciens encodes an RNase. When Barnase gene is driven by TA29 promoter, it is expressed only in tapetum cells causing their degeneration. Transgenic tobacco and Brassica napus plants expressing Barnase in their tapetum cells were completely male sterile. Another gene, Barstar, from the same bacterium encodes a protein, which is a highly specific inhibitor of Barnase RNase. Therefore, transgenic plants expressing both Barstar and Barnase are fully male fertile.
The Barnase gene has been linked to bar gene, which specifies resistance to the herbicide phosphinothricin. This male sterile line can be maintained by crossing it with any male fertile line. The progeny so obtained contain 1 male sterile : 1 male fertile plants; the latter are easily eliminated at ling stage by a phosphinothricin spray. The male sterile plants are crossed with a homozygous Barstar it serves as restorer line) to obtain male fertile hybrid progeny (Fig. 6.2). This system of male lity is vet to be commercially used, although it is now available in maize, cauliflower, tomato wheat and chicory.
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