1代雜種 種子生産에 DNA 再組合 技術의 利用

Utilization of recombinant DNA technology in the production on F₁hybrid seed

Male-sterility(MS) and self-incompatibility(SI), biological phenomena occurring in nature in the higher plant species, are the ways of the plants ensuring exclusively outcrossing. For several decades breeders have exploited these natural systems for the production of F₁ hybrid seed. Recently thanks to the improvement of DNA manipulation techniques a novel way, on the one hand, of producing transgenic MS plants was developed, while, on the other, the causes of the arrest of pollen tube growth in the incompatible combinations in SI was clarified at molecular level. Present paper has reviewed Mariani et al.’s construction of chimaeric genes obtaind by fusing the coding regions of the RNase genes from microorganisms to the promoters of tobacco’s tapetum-specific gene, and the use of these fused genes for the production of F₁ hybrid seed. Also reviewed is McClure et al. ’s demonstration of ribosomal RNA degradation in the pollen tube by the stylar RNase in the incompatible combinations of Nicotiana alata’s gametophytic self-incompatibility. Prior to the reviewing of these genetic engineering methods, relation between the tapetal layer and pollen differentiation in the anther was briefly described.