Genetic issues and pitfalls in transgenic plant breeding

Abstract

Transgene technology provides a powerful tool for developing traits that are otherwise difficult to achieve through conventional breeding. In order to effectively apply the technology to breeding, we need to understand how transgenes behave in plants. Transgenes may or may not follow Mendelian segregation; their expression can be significantly affected by integration positions and structures of the transgenic DNA in host genomes; transgenes may become unstable over generations, genetic background sand environmental conditions; and they may have significantly negative impact on expression of endogenous genes. If not well understood, the sehurdles could become significant barriers in transgenic breeding. This paper reviews some genetic issues and pitfalls that are often encountered in transgenic breeding. Because of the necessity of being brief, transgene expression, silencing, and breeding are the three areas of focuses in this discussion. While molecular mechanisms underlying many of the transgenic phenomena have not been completely understood, some practical ‘rules’ are now available for creating, evaluating and selecting desirable transgenic transformants. It can be certain that with more transgenic plants generated and characterized our knowledge of transgene genetics at both molecular and plant levels will continue to accumulate.