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Abstract Detail

Cell biology

Liu, Yuanyuan [1], Das, Orpita [1], Douglas, Carl J. [1].

The secondary cell wall regulatory network in Arabidopsis thaliana: role of a negative regulatory loop in maintaining metabolic homeostasis.

The TALE homeodomain transcription factor KNOTTED ARABIDOPSIS THALIANA7 (KNAT7) has been implicated in several studies as part of a regulatory network governing the commitment to secondary cell wall biosynthesis in the Arabidopsis inflorescence stems including lignin biosynthesis. In contrast to the strong feed-forward nature many components of the secondary cell wall transcription factor regulatory network, KNAT7 appears to play a negative regulatory role in conjunction with its interaction partner BELL1-LIKE HOMEODOMAIN6 (BLH6), forming a negative regulatory loop. The overlapping expression patterns of BLH6 and KNAT7 and the phenotypes of blh6, knat7, and blh6 knat7 loss of function mutants are consistent with the formation of a functional BLH6-KNAT7 heterodimer that represses commitment to secondary cell wall biosynthesis in interfascicular fibers. BLH6 and KNAT7 overexpression results in thinner interfascicular fiber secondary cell walls, and these phenotypes are dependent on the interacting partner. A major impact of the loss of BLH6 and KNAT7 function is increased lignin deposition enhanced expression of the gene encoding the HD-ZIP transcription factor REVOLUTA/INTERFASCICULAR FIBERLESS1 (REV/IFL1). Chromatin Immuno-Precipitation and transient expression assays show that KNAT7 and BHL6 bind to and repress the expression of REV, indicating that a key function of the BLH6-KNAT7 heterodimer is to repress REV expression. Preliminary data suggest that one physiological role of the BLH6-KNAT7-REV negative regulatory loop may be to repress lignin biosynthetic gene expression at night over the diurnal cycle, thus fine-tuning lignin biosynthesis and secondary cell wall deposition according to resource availability.

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1 - University of British Columbia, Botany, 6270 University Blvd, Vancouver, BC, V6T1Z4, Canada

Cell wall
transcription factor
regulatory network.

Presentation Type: Oral Paper:Papers for Topics
Session: 58
Location: Salon 17/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 8:00 AM
Number: 58001
Abstract ID:463
Candidate for Awards:None

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