The Arabidopsis R2R3 MYB Transcription Factor MYB15 Is a Key Regulator of Lignin Biosynthesis in Effector-Triggered Immunity

Abstract

Lignin, a major component of the secondary cell wall, is important for plant growth and development. Moreover, lignin plays a pivotal role in plant innate immunity. Lignin is readily deposited upon pathogen infection and functions as a physical barrier that limits the spread of pathogens. In this study, we show that an Arabidopsis MYB transcription factor MYB15 is required for the activation of lignin biosynthesis genes such as PAL, C4H, 4CL, HCT, C3′H, COMT, and CAD, and consequently lignin formation during effector-triggered immune responses. Upon challenge with the avirulent bacterial pathogen Pst DC3000 (AvrRpm1), lignin deposition and disease resistance were reduced in myb15 mutant plants. Furthermore, whereas invading pathogens, together with hypersensitive cell death, were restricted to the infection site in wild-type leaves, they spread beyond the infected area in myb15 mutants. The exogenous supply of the lignin monomer coniferyl alcohol restored lignin production and rescued immune defects in myb15 plants. These results demonstrate that regulation at the transcriptional level is key to pathogen-induced lignification and that MYB15 plays a central role in this process.

Two chemically distinct root lignin barriers control solute and water balance

“…This modulation of gene expression could explain the enhanced incorporation of p -coumaryl alcohol into the stress lignin we observed at endodermal cell corners. Interestingly, increased incorporation of p -coumaryl alcohol into lignin has been found in response to Pseudomonas syringae and is partially controlled by the MYB15 transcription factor 39 . MYB15 is an activator of basal immunity in A. thaliana through induction of the synthesis of defence lignin and soluble phenolics 38 .…”

MYB Transcription Factors and Its Regulation in Secondary Cell Wall Formation and Lignin Biosynthesis during Xylem Development

“…MYB TFs play an important role in the biosynthesis of lignin. For example, PAL (MYB8, [ 32 ]; MYB15, [ 33 ]; MYB46, [ 34 ]; MYB58 and MYB63, [ 35 ]), C4H (MYB15, [ 33 ]; MYB46, [ 34 ]), 4CL (MYB15, [ 33 ]; MYB46, [ 34 ]; MYB58 and MYB63, [ 35 ]), HCT (MYB46, [ 34 ]), C3H (MYB46, [ 34 ]; MYB58 and MYB63, [ 35 ]), CCoAOMT (MYB46, [ 34 ]; MYB58 and MYB63, [ 35 ]), F5H (MYB103, [ 35 , 36 , 37 ]), CCR (MYB46, [ 34 ]; MYB58 and MYB63, [ 35 ]), and CAD (MYB15, [ 33 ]; MYB46, [ 34 ]; MYB58 and MYB63, [ 35 ]).…”

“…Analyzing the regulatory network of MYB transcription factors in the formation of the Arabidopsis secondary wall can promote related research in other plants. A large number of studies have also proved that Arabidopsis is a good material for studying the formation of secondary walls [ 5 , 6 , 33 , 35 , 37 ]. Therefore, we take Arabidopsis as an example and draw Figure 1 to help you understand the important role of MYB transcription factor in the process of lignin synthesis more intuitively.…”

Commonly and Specifically Activated Defense Responses in Maize Disease Lesion Mimic Mutants Revealed by Integrated Transcriptomics and Metabolomics Analysis

“…Additionally, we also detected dramatic increases of the phenylpropanoid-based lignin accumulation in all three les mutants (Figure 6). It has long been proposed that lignin is involved in plant disease resistance because of its enhancement of cell wall rigidity, thus providing barriers against pathogen infection and restricting the infiltration of fungal enzymes and toxins into plant cells (Vance et al, 1980); this concept has been manifested by a recent finding that a lignin-deposited structure functions as a physical barrier similar to the Casparian strip, trapping pathogens and thereby terminating their growth (Lee et al, 2019), while MYB15 is a key TF that controls the defenseinduced lignification in Arabidopsis (Chezem et al, 2017;Kim et al, 2020).…”