KNOX1 genes regulate lignin deposition and composition in monocots and dicots

Townsley, Brad T.; Sinha, Neelima; Kang, Julie

doi:10.3389/fpls.2013.00121

Cited by 39 publications

(33 citation statements)

References 63 publications

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“…Mutations on CAD2 also caused easy shattering, further demonstrating that lignin plays an important role in that phenomenon. Our results are consistent with a previous report that overexpression of a KNOX gene in maize and tobacco (Nicotiana tabacum) reduces lignin concentrations by inhibiting at least two steps in that biosynthesis pathway (Townsley et al, 2013).…”

Section: The Osh15-sh5 Dimer Functions In Lignin Biosynthesissupporting

confidence: 93%

KNOX Protein OSH15 Induces Grain Shattering by Repressing Lignin Biosynthesis Genes

et al. 2017

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Seed shattering is an agronomically important trait. Two major domestication factors are responsible for this: qSH1 and SH5. Whereas qSH1 functions in cell differentiation in the abscission zone (AZ), a major role of SH5 is the repression of lignin deposition. We have determined that a KNOX protein, OSH15, also controls seed shattering. Knockdown mutations of OSH15 showed reduced seed-shattering phenotypes. Coimmunoprecipitation experiments revealed that OSH15 interacts with SH5 and qSH1, two proteins in the BELL homeobox family. In transgenic plants carrying the OSH15 promoter-GUS reporter construct, the reporter gene was preferentially expressed in the AZ during young spikelet development. The RNA in situ hybridization experiment also showed that OSH15 messenger RNAs were abundant in the AZ during spikelet development. Analyses of osh15 SH5-D double mutants showed that SH5 could not increase the degree of seed shattering when OSH15 was absent, indicating that SH5 functions together with OSH15. In addition to the seedshattering phenotype, osh15 mutants displayed dwarfism and accumulated a higher amount of lignin in internodes due to increased expression of the genes involved in lignin biosynthesis. Knockout mutations of CAD2, which encodes an enzyme for the last step in the monolignol biosynthesis pathway, caused an easy seed-shattering phenotype by reducing lignin deposition in the AZ. This indicated that the lignin level is an important determinant of seed shattering in rice (Oryza sativa). Chromatin immunoprecipitation assays demonstrated that both OSH15 and SH5 interact directly with CAD2 chromatin. We conclude that OSH15 and SH5 form a dimer that enhances seed shattering by directly inhibiting lignin biosynthesis genes.

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Section: The Osh15-sh5 Dimer Functions In Lignin Biosynthesissupporting

confidence: 93%

KNOX Protein OSH15 Induces Grain Shattering by Repressing Lignin Biosynthesis Genes

et al. 2017

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“…Thus, class I KNOX genes lower GA levels and activate CK accumulation. In addition, it was also reported that KNOX genes repress the biosynthesis of lignin, a major secondary cell wall component in Arabidopsis and maize [33,34] (Figure 2). …”

Section: Knox Downstream Pathwaysmentioning

confidence: 85%

Diverse functions of KNOX transcription factors in the diploid body plan of plants

Tsuda

Hake

2015

Current Opinion in Plant Biology

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KNOX genes were initially found as shoot meristem regulators in angiosperms. Recent studies in diverse plant lineages however, have revealed the divergence of KNOX gene function during the evolution of diploid body plans. Using genomic approaches, class I KNOX transcription factors have been shown to regulate multiple hormone pathways including auxin and brassinosteroid as well as many transcription factors that play important roles in plant development. Class I KNOX proteins appear to be activators, whereas class II proteins act as repressors in transcriptional regulation of their target genes.

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“…The expression pattern of CCOMT and CAD indicated that lignin biosynthesis was reduced during the early stage of SR development. In addition, upregulation of KNOX1 in I-stage and S-stage was negatively correlated with the expression of lignin biosynthesis key genes (CCOMT and CAD) (Guo et al 2001;Townsley et al 2013) suggesting that reduction of lignin biosynthesis corresponds to SR development (Firon et al 2013;Testone et al 2012).…”

Section: Functional Analysis Of Significant Genes During Phase Transimentioning

confidence: 99%

Genome-wide analysis reveals phytohormone action during cassava storage root initiation

et al. 2015

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Development of storage roots is a process associated with a phase change from cell division and elongation to radial growth and accumulation of massive amounts of reserve substances such as starch. Knowledge of the regulation of cassava storage root formation has accumulated over time; however, gene regulation during the initiation and early stage of storage root development is still poorly understood. In this study, transcription profiling of fibrous, intermediate and storage roots at eight weeks old were investigated using a 60-mer-oligo microarray. Transcription and gene expression were found to be the key regulating processes during the transition stage from fibrous to intermediate roots, while homeostasis and signal transduction influenced regulation from intermediate roots to storage roots. Clustering analysis of significant genes and transcription factors (TF) indicated that a number of phytohormone-related TF were differentially expressed; therefore, phytohormone-related genes were assembled into a network of correlative nodes. We propose a model showing the relationship between KNOX1 and phytohormones during storage root initiation. Exogeneous treatment of phytohormones N (6) -benzylaminopurine and 1-Naphthaleneacetic acid were used to induce the storage root initiation stage and to investigate expression patterns of the genes involved in storage root initiation. The results support the hypothesis that phytohormones are acting in concert to regulate the onset of cassava storage root development. Moreover, MeAGL20 is a factor that might play an important role at the onset of storage root initiation when the root tip becomes swollen.

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KNOX1 genes regulate lignin deposition and composition in monocots and dicots

Cited by 39 publications

References 63 publications

KNOX Protein OSH15 Induces Grain Shattering by Repressing Lignin Biosynthesis Genes

KNOX Protein OSH15 Induces Grain Shattering by Repressing Lignin Biosynthesis Genes

Diverse functions of KNOX transcription factors in the diploid body plan of plants

Genome-wide analysis reveals phytohormone action during cassava storage root initiation

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