向光性
光敏色素
拟南芥
隐色素
黄化
避光
下胚轴
嗜光蛋白
拟南芥
生长素
蓝光
远红色
生物
植物
细胞生物学
突变体
生物物理学
红灯
物理
生物化学
基因
生物钟
光电子学
酶
作者
Alessandra Boccaccini,Martina Legris,Johanna Krahmer,Laure Allenbach Petrolati,Anupama Goyal,Carlos S. Galván-Ampudia,Teva Vernoux,Elisabeth Karayekov,Jorge J. Casal,Christian Fankhauser
标识
DOI:10.1101/2020.02.28.969725
摘要
Abstract Shade-avoiding plants including Arabidopsis thaliana display a number of growth responses elicited by shade cues including elongation of stem-like structures and repositioning of leaves. Shade also promotes phototropism of de-etiolated seedlings through repression of phytochrome B (phyB) presumably to enhance capture of unfiltered sunlight. Light cues indicative of shade include a reduction in the blue and red portions of the solar spectrum and a low red to far-red ratio. Here we show that in Arabidopsis seedlings both low blue and a low red to far-red ratio are required to rapidly enhance phototropism. However, prolonged low blue treatments through reduced cryptochrome 1 (cry1) activation are sufficient to promote phototropism. The enhanced phototropic response of cry1 mutants in the lab and in response to natural canopies depends on PHYTOCHROME INTERACTING FACTORs ( PIFs ). In favorable light conditions, cry1 limits the expression of PIF4 while in low blue light PIF4 expression increases, which contributes to phototropic enhancement. The analysis of a quantitative DII auxin reporter indicates that low blue light leads to enhanced auxin levels in the hypocotyl and, upon phototropic stimulation, a steeper auxin gradient across the hypocotyl. We conclude that phototropic enhancement by canopy shade results from the combined activities of phytochrome B and cry1 that converge on PIF regulation. ONE SENTENCE SUMMARY The persistent depletion of blue light in natural canopy shade relieves the inhibitory effect of cryptochrome 1 on PIF4, enhancing phototropism in de-etiolated Arabidopsis seedlings. Financial support This work was supported by the University of Lausanne and a grant from the Swiss National Science foundation (n° 310030B_179558 to C.F.); Human Frontier Science Program organization (HFSP) Grant RPG0054-2013, ANR-12-BSV6-0005 grant (AuxiFlo) to T.V.; The University of Buenos Aires (Grant 20020100100437 to J. J. C.), and Agencia Nacional de Promoción Científica y Tecnológica of Argentina (Grant PICT-2018-01695 to J. J. C.). Alessandra Boccaccini and Martina Legris are funded by Marie Curie fellowships H2020-MSCA-IF-2017 grants CRoSh 796283 and Flat-Leaf 796443 respectively.
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