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Article|05 Jan 2022|OPEN
Integrated transcriptome and proteome analysis reveals brassinosteroid-mediated regulation of cambium initiation and patterning in woody stem.
Congpeng Wang1,4 , Naixu Liu1 , Zhao Geng1 , Meijing Ji1 , Shumin Wang2 , Yamei Zhuang2 , Dian Wang3 , Guo He2 , Shutang Zhao5 and Gongke Zhou1,4 , , Guohua Chai,1,4 ,
1College of Resources and Environment, Qingdao Agricultural University, Qingdao 266109, China
2Qingdao Institute of BioEnergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
3College of Agronomy, Qingdao Agricultural University, Qingdao 266109, China
4Academy of Dongying Efficient Agricultural Technology and Industry on Saline and Alkaline Land in Collaboration with Qingdao Agricultural University, Dongying 257000, China
5State Key Laboratory of Tree Genetics and Breeding, Research Institute of Forestry, Chinese Academy of Forestry, Beijing 100091, China
*Corresponding author. E-mail: zhougk@qau.edu.cn,chaigh@qau.edu.cn

Horticulture Research 9,
Article number: uhab048 (2022)
doi: https://doi.org/10.1093/hr/uhab048
Views: 170

Received: 24 Feb 2021
Revised: 30 Jun 2021
Accepted: 20 Aug 2021
Published online: 05 Jan 2022

Abstract

Wood formation involves sequential developmental events requiring the coordination of multiple hormones. Brassinosteroids (BRs) play a key role in wood development, but little is known about the cellular and molecular processes that underlie wood formation in tree species. Here, we generated transgenic poplar lines with edited PdBRI1 genes, which are orthologs of Arabidopsis vascular-enriched BR receptors, and showed how inhibition of BR signaling influences wood development at the mRNA and/or proteome level. Six Populus PdBRI1 genes formed three gene pairs, each of which was highly expressed in basal stems. Simultaneous mutation of PdBRI1–1−2, −3 and − 6, which are orthologs of the Arabidopsis vascular-enriched BR receptors BRI1BRL1 and BRL3, resulted in severe growth defects. In particular, the stems of these mutant lines displayed a discontinuous cambial ring and patterning defects in derived secondary vascular tissues. Abnormal cambial formation within the cortical parenchyma was also observed in the stems of pdbri1–1;2;3;6. Transgenic poplar plants expressing edited versions of PdBRI1–1 or PdBRI1–1;2;6 exhibited phenotypic alterations in stem development at 4.5 months of growth, indicating that there is functional redundancy among these PdBRI1 genes. Integrated analysis of the transcriptome and proteome of pdbri1–1;2;3;6 stems revealed differential expression of a number of genes/proteins associated with wood development and hormones. Concordant (16%) and discordant (84%) regulation of mRNA and protein expression, including wood-associated mRNA/protein expression, was found in pdbri1–1;2;3;6 stems. This study found a dual role of BRs in procambial cell division and xylem differentiation and provides insights into the multiple layers of gene regulation that contribute to wood formation in Populus.