PIFs coordinate shade avoidance by inhibiting auxin repressor ARF18 and metabolic regulator QQS

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Authors	JIA Yuebin KONG Xiangpei HU Kongqin CAO Mengqiang LIU Jiajia MA Changle GUO Siyi XIANZHENG Yuan ZHAO Shan ROBERT BOISIVON Helene LI Cuiling TIAN Huiyu DING Zhaojun
Year of publication	2020
Type	Article in Periodical
Magazine / Source	New Phytologist
MU Faculty or unit	Central European Institute of Technology
Citation
Web	publication on publisher website
Doi	http://dx.doi.org/10.1111/nph.16732
Keywords	shae avoidance; PIFs; ARF18; QQS; auxin
Description	Shade avoidance syndrome (SAS) arises in densely growing plants that compete for light. In Arabidopsis thaliana, PIF proteins link the perception of shade to stem elongation via auxin production. Here, we report that PIFs inhibit the shade-induced expression of AUXIN RESPONSE FACTOR 18 (ARF18), and ARF18 represses auxin signaling. Therefore, PIFs-mediated inhibition of ARF18 enhances auxin-dependent hypocotyl elongation in simulated shade. Furthermore, we show that both PIFs and ARF18 directly repress QuaQuine Starch (QQS), which controls the allocation of carbon and nitrogen. Shade-repressed QQS attenuates the conversion of starch to protein and thus reduced leaf area. Our results suggest that PIFs-dependent gene regulation coordinates multiple SAS responses, including altered stem growth via ARF18, as well as altered leaf growth and metabolism via QQS.
Related projects:	Signal integration and epigenetic reprograming for plant productivity