A Chinese White Pear (Pyrus bretschneideri) BZR Gene PbBZR1 Act as a Transcriptional Repressor of Lignin Biosynthetic Genes in Fruits

Abstract

BZR transcription factors play essential roles in plant growth and environmental stimuli, and they are also the positive regulators of Brassinosteroid (BR) signal transduction in diverse plants. In addition, BZR TFs, as crucial regulators of BR synthesis, may have multiple stress-resistance functions and their related regulatory mechanisms have been well illustrated in model plants. Here, we carried out a genome-wide identification of BZR members in Chinese pear ( Pyrus bretschneideri ) and identified 13 members. By comparative analysis in five Rosaceae genomes, BZR members in the pear genome may have undergone large-scale duplication events during evolution. Purifying selection played an important role in almost all of the orthologous and paralogous gene pairs. According to the expression analysis of the PbBZRs during fruit development, three PbBZRs were selected for detailed analysis. Transcriptional activation assays presented that PbBZR1 repressed the promoters of P. bretschneideri lignin biosynthetic genes, such as PbCES9 , PbCOMT3 , and PbHCT6 . Our study traces the evolution of BZR gene family members in Rosaceae genomes and illustrates that the rates of gene loss and gain are far from equilibrium in different species. At the same time, our results suggest that PbBZR1 may be involved in the negative regulation of lignin biosynthesis.

Integrative Analysis of the DICER-like (DCL) Genes From Peach (Prunus persica): A Critical Role in Response to Drought Stress

“…However, F. vesca and P. armeniaca had equal number of DCL copies, although they have different genome size: F. vesca (219.29 Mb) and P. armeniaca (206.10 Mb). Rosaceae species share an ancient whole-genome duplication (WGD) event (Wu et al, 2013;Cao et al, 2020a), while experienced a more recent WGD event (Wu et al, 2013;Daccord et al, 2017), which might explain why M. x domestica contains the highest number of DCL gene copies among the studies Rosaceae species.…”

Characterization of the ABC Transporter G Subfamily in Pomegranate and Function Analysis of PgrABCG14

“…In plants, the staple biosynthetic pathway of lignin is well understood: at the first step, monolignols including p -coumaryl alcohol (H-type monolignol), coniferyl alcohol (G-type monolignol), and sinapyl alcohol (S-type monolignol), are produced by phenylpropanoid pathways within the plant cell; at the second step, the monolignols are transported across the plasma membrane to the cell wall; and at the last step, the monolignols are polymerized to form lignin under the action of peroxidase and laccase [ 6 , 7 , 8 ]. To date, many genes encoding key enzymes and transcription factors that are involved in the biosynthesis and polymerization of monolignols have been characterized [ 9 , 10 , 11 , 12 , 13 ]. Recently, studies have demonstrated that monolignols can be passively diffused from inside the cell out to the cell wall through lipid bilayers [ 14 ].…”

Transcriptional regulation of fleshy fruit texture

“…The underlying molecular mechanism has been shown to involve PbrMYB169 activation of the promotors of lignin biosynthesis genes, including PbrC3H1 , PbrCCR1 , PbrCCOMT2 , PbrCAD , Pbr4CL1 , Pbr4CL2 , PbrHCT2 , and PbrLAC18 (Xue et al, 2019b). This is opposed by PbBZR1, which suppresses the activation of the promoters of lignin biosynthesis genes PbCOMT3 and PbHCT6 , and transient silencing PbBZR1 in pear increased lignin content and induced the expression of 15 lignin biosynthetic genes (Cao et al, 2020). Wang et al (2021) have characterized a NAC TF, PbrNSC (NAC STONE CELL PROMOTING FACTOR), which is phylogenetically related to AtNST1/2/3, as a regulator of lignocellulose formation associated with stone cells in pear fruit by integrating co‐expression networks and eQTLs (expression QTL) in 206 pear cultivars.…”