The class II KNOX transcription factors KNAT3 and KNAT7 synergistically regulate monolignol biosynthesis in Arabidopsis
- 19 September 2020
- journal article
- research article
- Published by Oxford University Press (OUP) in Journal of Experimental Botany
- Vol. 71 (18), 5469-5483
- https://doi.org/10.1093/jxb/eraa266
Abstract
The function of the transcription factor KNOTTED ARABIDOPSIS THALIANA7 (KNAT7) is still unclear since it appears to be either a negative or a positive regulator for secondary cell wall deposition with its loss-of-function mutant displaying thicker interfascicular and xylary fiber cell walls but thinner vessel cell walls in inflorescence stems. To explore the exact function of KNAT7, class II KNOTTED1-LIKE HOMEOBOX (KNOX II) genes in Arabidopsis including KNAT3, KNAT4, and KNAT5 were studied together. By chimeric repressor technology, we found that both KNAT3 and KNAT7 repressors exhibited a similar dwarf phenotype. Both KNAT3 and KNAT7 genes were expressed in the inflorescence stems and the knat3 knat7 double mutant exhibited a dwarf phenotype similar to the repressor lines. A stem cross-section of knat3 knat7 displayed an enhanced irregular xylem phenotype as compared with the single mutants, and its cell wall thickness in xylem vessels and interfascicular fibers was significantly reduced. Analysis of cell wall chemical composition revealed that syringyl lignin was significantly decreased while guaiacyl lignin was increased in the knat3 knat7 double mutant. Coincidently, the knat3 knat7 transcriptome showed that most lignin pathway genes were activated, whereas the syringyl lignin-related gene Ferulate 5-Hydroxylase (F5H) was down-regulated. Protein interaction analysis revealed that KNAT3 and KNAT7 can form a heterodimer, and KNAT3, but not KNAT7, can interact with the key secondary cell wall formation transcription factors NST1/2, which suggests that the KNAT3NST1/2 heterodimer complex regulates F5H to promote syringyl lignin synthesis. These results indicate that KNAT3 and KNAT7 synergistically work together to promote secondary cell wall biosynthesis.Funding Information
- National Natural Science Foundation of China (31870653, 31670670, 31811530009)
This publication has 65 references indexed in Scilit:
- Comparative structure and biomechanics of plant primary and secondary cell wallsFrontiers in Plant Science, 2012
- The Genetics of Lignin Biosynthesis: Connecting Genotype to PhenotypeAnnual Review of Genetics, 2010
- Arabidopsis VASCULAR-RELATED NAC-DOMAIN6 Directly Regulates the Genes That Govern Programmed Cell Death and Secondary Wall Formation during Xylem DifferentiationTHE PLANT CELL ONLINE, 2010
- MYB75 Functions in Regulation of Secondary Cell Wall Formation in the Arabidopsis Inflorescence StemPlant Physiology, 2010
- Syringyl lignin biosynthesis is directly regulated by a secondary cell wall master switchProceedings of the National Academy of Sciences of the United States of America, 2010
- A Comprehensive Classification and Evolutionary Analysis of Plant Homeobox GenesMolecular Biology and Evolution, 2009
- MYB58 and MYB63 Are Transcriptional Activators of the Lignin Biosynthetic Pathway during Secondary Cell Wall Formation in ArabidopsisTHE PLANT CELL ONLINE, 2009
- A Battery of Transcription Factors Involved in the Regulation of Secondary Cell Wall Biosynthesis in ArabidopsisTHE PLANT CELL ONLINE, 2008
- Unique aspects of the grass cell wallCurrent Opinion in Plant Biology, 2008
- SND1, a NAC Domain Transcription Factor, Is a Key Regulator of Secondary Wall Synthesis in Fibers ofArabidopsisTHE PLANT CELL ONLINE, 2006