Genetically Engineered Pollination Control Systems For Hybrid Seed Production
Hybrids are contributing a lot in the field of Agriculture with higher production and good quality produce. The raw material for hybrids are the seeds. In the process of Hybrid Seed production, there is requiremet of land labour and technical know how. so development of hybrid seeds with inculcation of genetic engineering will be helpful.
Heterosis, superior or inferior performance of hybrid over both the parents is one of the biological wonders. It can be exploited in the form of hybrids or synthetic varieties. The foundation of hybrid seed technology goes back to the second part of 19th century in maize. Now a days hybrid seed technology has been extended to many grain and vegetable crops. Prevention of self and inter line pollination is most critical step in commercial hybrid seed production. The cost of hybrid seed is determined by the technology used to achieve this objective.
Present day pollination control mechanisms have limited usage in hybrid seed production. In order to widen hybrid cultivar cultivation, efficient exploitation of heterosis is necessary. Genetically engineered pollination control systems acts as tools through which heterosis can be exploited efficiently. These include: Barnase - Barstar system where a toxin gene was expressed in Tobacco to achieve male sterility. Instead of expressing a toxin gene, hormone engineering (Huang, 2004) and strategies involving gene silencing were used to obtain male sterility. In all the above cases the transformed female parent would become male sterile which requires restoration systems in order to utilize them in the crops where seed is the economic product. To avoid the above problem pollen self destructive male sterility (Neumann et al., 2004) was used in Brassica where the transformed female parent is male fertile which when sprayed with N- acetyl phosphinothricin would become male sterile.
Recent findings showing the importance of TAZ1 gene in tapetum and pollen development in Petunia (Sanjay et al., 2002); TPD1 gene in anther specialization (Shu et al., 2003) and SETH 1, SETH 2 in pollen germination and tube growth (Eric et al., 2004) in Arabidopsis are potential sources for developing new pollination control mechanisms which can be used in hybrid seed production.
Eric, L., David, H., Johnson, A., Borner, G.H.H., Lilley, K.S., Paul, D., Uleli, G. and Davis, T., 2004, SETH 1 and SETH 2, two components of the glycosylphosphatidyl inositol anchor biosynthetic pathway, are required for pollen germination and tube growth in Arabidopsis. Plant Cell, 16: 229-240.
Huang, 2004, Genetic engineering of chemically reversible male sterility by expressing CKX 1 in transgenic maize. www. abstracts.aspb. org.
Neumann, K., Kohne, S., Sonnatag, K. and Broer, I., 2004, Induced sterility in transgenic rapeseed. www. regional.org.
Sanjay, K., Akira, K. and Hiroshi, T., 2002, Silencing of the tapetum specific zinc finger gene TAZ1 causes premature degradation of tapetum and pollen abortion in Petunia. Plant Cell, 14: 2353-2367.
Shu, L.Y., Li, F.X., Hui, Z.M., Ching, S.P., WeI, C.Y., Lixi, J., Venkatesan, S. and De, Y., 2003, Tapetum determinant 1 is required for cell specialization in the Arabidopsis anther. Plant Cell, 15: 2792-2804.
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