Department of Plant Ecology and Evolution, Evolutionary Biology Center, Uppsala University, SE-752 36 Uppsala, Sweden.
Plant Physiol. 2013 Oct;163(2):792-803. doi: 10.1104/pp.113.224139. Epub 2013 Aug 19.
The timing of bud set, as one determinant of the annual growth rhythm, is critical for local adaptation of the conifer Norway spruce (Picea abies). Previous gene expression and population genetic studies have suggested a role for P. abies FLOWERING LOCUS T/TERMINAL FLOWER1-Like2 (PaFTL2) in the control of growth cessation and bud set in Norway spruce as well as in local adaptation resulting in clinal variation for timing of bud set. Using transgenic plants with PaFTL2 driven by an inducible promoter, we found that PaFTL2 indeed induces bud set and most probably also growth cessation. PaFTL2 shows high expression around the procambium and vascular tissue and in the crown region in buds of both seedlings and older trees. Furthermore, PaFTL2 expression is induced in vegetative shoots and all bud types in late summer, when growth cessation occurs. This supports the notion that PaFTL2 is involved in growth cessation. A close paralog to PaFTL2, PaFTL1, is strongly expressed in meristems during the summer, possibly to repress meristem activity and the formation of needle primordia during this period. The temporal and spatial expression of PaFTL1 and PaFTL2 largely complement each other, which suggests that they act in concert to control perennial growth in Norway spruce.
芽休眠的时间作为年度生长节律的一个决定因素，对挪威云杉（Picea abies）的局部适应至关重要。先前的基因表达和群体遗传学研究表明，挪威云杉的开花位点 T/终端花 1 样 2（PaFTL2）在控制生长停止和芽休眠以及导致芽休眠时间的地理变异的局部适应中起作用。使用由诱导启动子驱动的 PaFTL2 的转基因植物，我们发现 PaFTL2 确实诱导芽休眠，并且很可能还诱导生长停止。PaFTL2 在幼苗和老树芽的原形成层和维管束组织以及冠部区域表达较高。此外，在夏末发生生长停止时，PaFTL2 在营养枝和所有芽类型中表达诱导。这支持了 PaFTL2 参与生长停止的观点。PaFTL2 的一个紧密的平行物 PaFTL1 在夏季强烈表达于分生组织中，可能在这段时间内抑制分生组织活性和针状原基的形成。PaFTL1 和 PaFTL2 的时空表达在很大程度上相互补充，这表明它们协同作用控制挪威云杉的多年生生长。
