Cover image: Pictured is a flower of Nesocodon mauritianus displaying redcolored nectar—a rare trait among flowering plants. Rahul Roy et al. determined that the red color comes from the alkaloid nesocodin and that the action of secreted enzymes changes the pale yellow, acidic nectar to deep red, alkaline nectar. Nesocodin attracts visiting geckos and is also found in the distantly related species Jaltomata herrerae, which is visited by hummingbirds. The results suggest that nesocodin likely developed in the two species through convergent evolution and show how plant–animal interactions influence the development of adaptive pigments. See the article by Roy et al., e2114420119. Image credit: Clay J. Carter and Rahul Roy.
PLANT CELL:中国西南大学发现调控植物顶端弯钩形成的新机制
土壤中萌发生长的植物在黑暗条件下生长直到其突破土壤表面。为了帮助植物突破土层，双子叶植物形成一个顶端弯钩。油菜素内酯在顶端弯钩形成过程中发挥重要作用，但是其具体机制尚不清楚。拟南芥的SMALL AUXIN UP RNA17 (SAUR17)是顶端弯钩形成的重要调控子。本研究显示乙烯和油菜素内酯可以通过包括PHYTOCHROME-INTERACTING FACTORs (PIFs), ETHYLENE INSENSITIVE 3 (EIN3) EIN3-LIKE 1 (EIL1), BRASSINAZOLE RESISTANT1 (BZR1)转录调控复合物促进SAUR17的表达。BZR1可以结合到SAUR17的启动子上来调控它的表达，EIN3和PIFs可以提高BZR1结合靶基因启动子序列的能力，而EIN3, PIF3/4的稳定性依赖于BR信号。BZR1可以抑制 EIN3-BINDING F-BOX 1/ 2，这两个基因参与了对EIN3和PIF3蛋白降解过程，这样就导致EIN3和PIF3的蛋白稳定性增高，从而强化了油菜素内酯信号途径对 SAUR17 和 HOOKLESS1的表达调控，从而促进了顶端弯钩的形成。
Figure. BR integration in pathways controlling apical hook formation. A) Constitutive expression of SAUR17 suppressed the cotyledon-opening phenotype of pifq in the dark. Phenotypes of the dark-grown pifq mutant and three independent transgenic lines of Enh35S:ProSAUR17:SAUR17-GFP/pifq compared to wildtype (Col). B) A model illustrating the effect of BR in promoting the etiolated development of apical organs in the darkness. BR inhibits the transcription of EBF1/2 via BZR1, resulting in stabilization of the EIN3/EIL1 and PIF3 proteins.
原文信息：Wang J, Sun N, Zheng L, Zhang F, Xiang M, Chen H, Deng XW, Wei N (2022) Brassinosteroids promote etiolated apical structures in darkness by amplifying the ethylene response via the EBF-EIN3/PIF3 circuit. Plant Cell doi: 10.1093/plcell/koac316
