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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2019.01082

Hypocotyl Elongation Inhibition of Melatonin Involves in Repressing Brassinosteroids Biosynthesis in Arabidopsis

 Fangjie Xiong1, Fengping Zhuo1,  Russel J. Reiter2, Lingling Wang3, Zhenzhen Wei3, Kexuan Deng1, Yun Song3, Ghulam Qanmber3, Li Feng1,  Zuoren Yang3, Fuguang Li3 and  Ren Maozhi1*
  • 1Chongqing University, China
  • 2The University of Texas Health Science Center at San Antonio, United States
  • 3National Key Laboratory of Cotton Biology, Institute of Cotton Research, Chinese Academy of Agricultural Science, China

Melatonin functions as a plant hormone/regulator in the regulation of growth and development. However, the underlying mechanisms are still unclear. In this study, we found high dose of melatonin inhibited hypocotyl elongation in a dose-dependent manner in Arabidopsis. Expression profile analysis showed that hypocotyl growth inhibition by melatonin was involved in reprograming the expression of cell elongation genes and brassinosteroids (BRs) biosynthetic genes. Furthermore, similar to BR biosynthetic inhibitor brassinazole (BRZ), high concentration of melatonin upregulated BR-biosynthetic genes and downregulated BR-induced genes involved in cell elongation, while melatonin was inefficient to brassinazole-resistant mutants like the bzr1-1D and bes1-D in hypocotyl inhibition. Comparative expression profile analysis showed opposite expression mode between melatonin-induced and bzr1-1D or brassinolide (BL)-induced in their co-regulated genes. Additionally, exogenous BL rescued the repressive phenotype of BR biosynthesis deficient mutant like det2-1 even in presence of high dose melatonin, but not BR receptor mutant bri1-5 or signal transduction mutant bin2-1. Biochemical analysis furtherly confirmed melatonin reduced endogenous BRs levels in a dose-dependent manner in Arabidopsis. Taken together, these results indicate that melatonin inhibits BRs biosynthesis but does not block BR signaling in inhibition of hypocotyl elongation, and extends insights the role of melatonin in cross-talking with plant hormones signaling.

Keywords: Melatonin, Hypocotyl elongation, BRs biosynthesis, Gene Expression, Arabidopsis

Received: 24 May 2019; Accepted: 08 Aug 2019.

Copyright: © 2019 Xiong, Zhuo, Reiter, Wang, Wei, Deng, Song, Qanmber, Feng, Yang, Li and Maozhi. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Prof. Ren Maozhi, Chongqing University, Chongqing, 400030, Chongqing, China, renmaozhi@cqu.edu.cn