The phytohormone (植物激素) gibberellin (GA) is a key regulator of plant growth and development. Although the upstream regulation and downstream responses to GA vary across cells and tissues, developmental stages and environmental conditions, the spatiotemporal distribution (时空分布) of GA in vivo remains unclear. Using a combinatorial screen in yeast, we engineered an optogenetic biosensor (光遗传生物传感器), GIBBERELLIN PERCEPTION SENSOR 1 (GPS1; 赤霉素感知传感器), that senses nanomolar (纳摩尔) levels of bioactive GAs. Arabidopsis thaliana plants expressing a nuclear localized GPS1 report on GAs at the cellular level. GA gradients were correlated with gradients of cell length in rapidly elongating roots and dark-grown hypocotyls (下胚轴). In roots, accumulation of exogenously applied (外加的) GA also correlated with cell length, intimating (示意) that a root GA gradient can be established independently of GA biosynthesis. In hypocotyls, GA levels were reduced in a phytochrome interacting factor (pif) quadruple mutant (四突变体) in the dark and increased in a phytochrome double mutant in the light, indicating that PIFs elevate (提高) GA in the dark and that phytochrome inhibition of PIFs could lower GA in the light. As GA signalling directs hypocotyl elongation largely through promoting PIF activity, PIF promotion of GA accumulation represents a positive feedback loop within the molecular framework driving rapid hypocotyl growth.

研究方向：植物激素的荧光共振能量转移（FRET）生物感应器研究。

Published online: October 2, 2017.