A Phytochrome B-PIF4-MYC2/MYC4 module inhibits secondary cell wall thickening in response to shaded light

Fang Luo; Qian Zhang; Hu Xin; Hongtao Liu; Hongquan Yang; Monika S Doblin; Antony Bacic; Laigeng Li

doi:10.1016/j.xplc.2022.100416

A Phytochrome B-PIF4-MYC2/MYC4 module inhibits secondary cell wall thickening in response to shaded light

Plant Commun. 2022 Nov 14;3(6):100416. doi: 10.1016/j.xplc.2022.100416. Epub 2022 Aug 4.

Authors

Fang Luo¹, Qian Zhang¹, Hu Xin², Hongtao Liu³, Hongquan Yang⁴, Monika S Doblin⁵, Antony Bacic⁵, Laigeng Li⁶

Affiliations

¹ National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China; University of the Chinese Academy of Sciences, Beijing 100049, China.
² Key Laboratory of Biodiversity Conservation in Southwest, State Forestry Administration, Southwest Forestry University, Kunming 650224, China.
³ National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
⁴ College of Life and Environmental Sciences, Shanghai Normal University, Shanghai 200234, China.
⁵ La Trobe Institute for Agriculture and Food, School of Agriculture, Biomedicine and Environment, Department of Animal, Plant and Soil Sciences, AgriBio, La Trobe University, Bundoora, VIC 3086, Australia; Sino-Australia Plant Cell Wall Research Centre, State Key Laboratory of Subtropical Silviculture, School of Forestry and Biotechnology, Zhejiang A&F University, Hangzhou 311300, China.
⁶ National Key Laboratory of Plant Molecular Genetics, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai 200032, China. Electronic address: lgli@cemps.ac.cn.

Abstract

Secondary cell walls (SCWs) in stem cells provide mechanical strength and structural support for growth. SCW thickening varies under different light conditions. Our previous study revealed that blue light enhances SCW thickening through the redundant function of MYC2 and MYC4 directed by CRYPTOCHROME1 (CRY1) signaling in fiber cells of the Arabidopsis inflorescence stem. In this study, we find that the Arabidopsis PHYTOCHROME B mutant phyB displays thinner SCWs in stem fibers, but thicker SCWs are deposited in the PHYTOCHROME INTERACTING FACTOR (PIF) quadruple mutant pif1pif3pif4pif5 (pifq). The shaded light condition with a low ratio of red to far-red light inhibits stem SCW thickening. PIF4 interacts with MYC2 and MYC4 to affect their localization in nuclei, and this interaction results in inhibition of the MYCs' transactivation activity on the NST1 promoter. Genetic evidence shows that regulation of SCW thickening by PIFs is dependent on MYC2/MYC4 function. Together, the results of this study reveal a PHYB-PIF4-MYC2/MYC4 module that inhibits SCW thickening in fiber cells of the Arabidopsis stem.

Keywords: MYC2; far-red light; fiber cell; secondary cell wall; xylem.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Arabidopsis Proteins* / genetics
Arabidopsis* / genetics
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / genetics
Basic Helix-Loop-Helix Transcription Factors / genetics
Cell Wall
Phytochrome B / genetics
Phytochrome* / genetics
Trans-Activators / genetics
Transcription Factors / genetics

Substances

Phytochrome B
Arabidopsis Proteins
Phytochrome
MYC2 protein, Arabidopsis
Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
MYC4 protein, Arabidopsis
Trans-Activators
PIF4 protein, Arabidopsis
Basic Helix-Loop-Helix Transcription Factors
NST1 protein, Arabidopsis
Transcription Factors