Designing and constructing novel gene promoters to generate stress-tolerant plants without yield penalty

摘要

Although genetic engineering has become an important practice in agricultural biotechnology, how to properly control the expression of transgenes in transgenic plants remains a challenging task. Strong constitutive promoters are routinely used in plant transformation, but sometimes their use leads to undesirable secondary effects and negatively affects the overall performance of transgenic plants. In order to maximize the benefits of transgenes and to avoid unexpected negative impact, tissue-specificstress-/ABA-inducible promoters have been designed and constructed based on knowledge learned from studies of native promoters. Microarray analysis and bioinformatics are also employed in an extensive search for stress-/ABA-inducible and tissue-specificpromoters, and information obtained is used to broaden the foundation for constructing synthetic designer promoters. The efforts include (1) optimization of upstream ABA-/stress-responsive cis-acting elements such as AB responsive element (ABRE) and coupling element (CE), (2) a search for the most efficient minimal promoter and desirable introns, and (3) the addition of tissue-specific determinants. Various versions of synthetic stress-/ABA-inducible promoters have been constructed, and some of them have been tested in transgenic plants for the expression of beneficial genes in conferring stress tolerance. Although transgenic plants with either a strong constitutive promoter or synthetic stress-inducible promoter acquire an elevated level of stress tolerance, only the latter display normal growth and development without any apparent yield penalty under normal conditions.