Development of an early flowering system for poplar breeding and biosafety research

树种只有经过一个漫长的幼年期（营养期）才能开花（生殖期），这在某些树种中持续到40年是相当可变的。林木营养生长期长，阻碍了林木育种的发展。尽管大量的育种进展已经取得了集约育种的松树，杨树，桉树和其他一些类群，林木“品种”仍然可以被认为是几乎“野生植物”，几乎没有任何作物驯化的标志。也许林木基因工程提供的最有前途的前景之一是克服漫长的营养生长期。利用开花时间（FTi）和分生组织特性基因诱导树木早花的几种方法已经获得成功。然而，迄今为止，早花白杨系统往往显示出许多缺点，如干扰生长，小孢子发生，以及对木材形成等其他发育过程的意想不到的影响。本项目旨在建立一个更有效、更可靠的白杨开花诱导体系。早花对林木育种和遗传控制的生物安全研究具有重要价值。几种方法将使用FTi和花分生组织/器官身份基因的基因堆叠进行测试。将评价不同转基因品系的早花、生长性能和木材性质，以及所选白杨FTi和分生组织/器官同一性基因的基因表达。

Tree species produce flowers (reproductive phase) only after a prolonged juvenile phase (vegetative phase), which is quite variable lasting in some tree species until 40 years. The long vegetative phase has impeded the development of forest tree breeding. Even though substantial breeding progress has been made with intensively bred pines, poplars, eucalypts and a few other taxa, forest tree ‘cultivars’ can still be considered as nearly ‘wild plants’ with few if any of the hallmarks of crop domestication. Probably one of the most promising prospects offered by genetic engineering of forest trees is on overcoming the long vegetative phase. Several approaches have been successful on the induction of early flowering in trees using flowering time (FTi) and meristem identity genes. However, hitherto available early flowering poplar systems often show many drawbacks, like disturbed growth, microsporogenesis, and unexpected effects on other developmental processes like wood formation. This project aims to generate a more efficient and reliable system for the induction of flowering in poplar. Early flowering would be very valuable to forest tree breeding and biosafety research on genetic containment. Several approaches will be tested using gene stacking of FTi and flower meristen/organ identity genes. Early flowering, growth performance and wood properties of the different transgenic lines, as well as gene expression of selected poplar FTi and meristem/organ identity genes will be evaluated.