MYB-bHLH-TTG1 in a Multi-tiered Pathway Regulates Arabidopsis Seed Coat Mucilage Biosynthesis Genes Including PECTIN METHYLESTERASE INHIBITOR14 Required for Homogalacturonan Demethylesterification
- PMID: 37354456
- PMCID: PMC10434736
- DOI: 10.1093/pcp/pcad065
MYB-bHLH-TTG1 in a Multi-tiered Pathway Regulates Arabidopsis Seed Coat Mucilage Biosynthesis Genes Including PECTIN METHYLESTERASE INHIBITOR14 Required for Homogalacturonan Demethylesterification
Abstract
MYB-bHLH-TTG1 (MBW) transcription factor (TF) complexes regulate Arabidopsis seed coat biosynthesis pathways via a multi-tiered regulatory mechanism. The MYB genes include MYB5, MYB23 and TRANSPARENT TESTA2 (TT2), which regulate GLABRA2 (GL2), HOMEODOMAIN GLABROUS2 (HDG2) and TRANSPARENT TESTA GLABRA2 (TTG2). Here, we examine the role of PECTIN METHYLESTERASE INHIBITOR14 (PMEI14) in seed coat mucilage pectin methylesterification and provide evidence in support of multi-tiered regulation of seed coat mucilage biosynthesis genes including PMEI14. The PMEI14 promoter was active in the seed coat and developing embryo. A pmei14 mutant exhibited stronger attachment of the outer layer of seed coat mucilage, increased mucilage homogalacturonan demethylesterification and reduced seed coat radial cell wall thickness, results consistent with decreased PMEI activity giving rise to increased PME activity. Reduced mucilage release from the seeds of myb5, myb23, tt2 and gl2, hdg2, ttg2 triple mutants indicated that HDG2 and MYB23 play minor roles in seed coat mucilage deposition. Chromatin immunoprecipitation analysis found that MYB5, TT8 and seven mucilage pathway structural genes are directly regulated by MYB5. Expression levels of GL2, HDG2, TTG2 and nine mucilage biosynthesis genes including PMEI14 in the combinatorial mutant seeds indicated that these genes are positively regulated by at least two of those six TFs and that TTG1 and TTG2 are major regulators of PMEI14 expression. Our results show that MYB-bHLH-TTG1 complexes regulate mucilage biosynthesis genes, including PMEI14, both directly and indirectly via a three-tiered mechanism involving GL2, HDG2 and TTG2.
Keywords: Arabidopsis thaliana; Cell walls; MBW; Mucilage; PMEI; Pectin; Seed coat; TTG1; Transcription factors.
© The Author(s) 2023. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists.
Figures
![Fig. 1](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/10434736/bin/pcad065f1.gif)
![Fig. 2](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/10434736/bin/pcad065f2.gif)
![Fig. 3](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/10434736/bin/pcad065f3.gif)
![Fig. 4](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/10434736/bin/pcad065f4.gif)
![Fig. 5](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/10434736/bin/pcad065f5.gif)
![Fig. 6](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/10434736/bin/pcad065f6.gif)
![Fig. 7](https://www.ncbi.nlm.nih.gov/pmc/articles/instance/10434736/bin/pcad065f7.gif)
Similar articles
-
MYB-bHLH-TTG1 Regulates Arabidopsis Seed Coat Biosynthesis Pathways Directly and Indirectly via Multiple Tiers of Transcription Factors.Plant Cell Physiol. 2020 May 1;61(5):1005-1018. doi: 10.1093/pcp/pcaa027. Plant Cell Physiol. 2020. PMID: 32154880
-
MYB52 Negatively Regulates Pectin Demethylesterification in Seed Coat Mucilage.Plant Physiol. 2018 Apr;176(4):2737-2749. doi: 10.1104/pp.17.01771. Epub 2018 Feb 9. Plant Physiol. 2018. PMID: 29440562 Free PMC article.
-
Expression of PRX36, PMEI6 and SBT1.7 is controlled by complex transcription factor regulatory networks for proper seed coat mucilage extrusion.Plant Signal Behav. 2014;9(11):e977734. doi: 10.4161/15592324.2014.977734. Plant Signal Behav. 2014. PMID: 25531128 Free PMC article.
-
GLABRA2, A Common Regulator for Epidermal Cell Fate Determination and Anthocyanin Biosynthesis in Arabidopsis.Int J Mol Sci. 2019 Oct 9;20(20):4997. doi: 10.3390/ijms20204997. Int J Mol Sci. 2019. PMID: 31601032 Free PMC article. Review.
-
Regulation of seed coat mucilage production and modification in Arabidopsis.Plant Sci. 2023 Mar;328:111591. doi: 10.1016/j.plantsci.2023.111591. Epub 2023 Jan 6. Plant Sci. 2023. PMID: 36623642 Review.
Cited by
-
Genome-Wide Identification, Evolution, and Expression Analysis of the WD40 Subfamily in Oryza Genus.Int J Mol Sci. 2023 Oct 30;24(21):15776. doi: 10.3390/ijms242115776. Int J Mol Sci. 2023. PMID: 37958759 Free PMC article.
References
-
- Baudry A., Caboche M. and Lepiniec L. (2006) MYB and bHLH factors, allowing a strong and cell-specific accumulation of flavonoids in TT8 controls its own expression in a feedback regulation involving TTG1 and homologous Arabidopsis thaliana. Plant J. 46: 768–779. - PubMed
-
- Beeckman T., De Rycke R., Viane R. and Inze D. (2000) Histological study of seed coat development in Arabidopsis thaliana. J. Plant Res. 113: 139–148.
-
- Clough S.J. and Bent A.F. (1998) Floral dip: a simplified method for Agrobacterium-mediated transformation of Arabidopsis thaliana. Plant J. 16: 735–743. - PubMed
-
- Dean G.H., Jin Z., Shi L., Esfandiari E., McGee R., Nabata K., et al. (2017) Identification of a seed coat-specific promoter fragment from the Arabidopsis MUCILAGE-MODIFIED4 gene. Plant Mol. Biol. 95: 33–50. - PubMed
MeSH terms
Substances
Grants and funding
LinkOut - more resources
Full Text Sources
Research Materials
Miscellaneous