Figure 1. Regulation of homogalacturonan (HG) methylesterification in the plant cell wall (CW) in Arabidopsis. This schematic illustrates the multilayered regulation of HG methylesterification in the CW of the model plant Arabidopsis. The degree of methylesterification (DM) is modulated by numerous transcription factors (TFs) (LUH, BLH2, BLH4, ERF4, ETTIN, BLR, STK, and MYB52) that directly regulate pectin methylesterase (PME)/pectin methylesterase inhibitor (PMEI) expression, as well as by ubiquitin ligases (FLY1, FLY2, MUD1) that control PME recycling and stability. Hormones also modulate HG methylesterification. Ethylene and abscisic acid (ABA) promote HG demethylesterification, while gibberellic acid (GA) and brassinosteroids (BR) inhibit it. Auxin can either promote or inhibit HG demethylesterification, which might be determined by DM. In addition, apoplastic pH influences the enzymatic function of PME/PMEI through acidification driven by H+-ATPase, proton pump embedded in the plasma membrane (PM). Red arrows indicate positive regulation, blue arrow indicate negative regulation, and dashed indicated regulatory relationships that are not fully confirmed. The multiple layers described above-including TFs, post-transcriptional regulators, hormones, and apoplastic pH—are interwoven to form a complex network controlling HG methylesterification. Arrows indicate positive (red) or negative (blue) regulation. The red arrows with double heads refer to indirect positive regulation. Black dotted lines suggest interactions that are not fully characterized or confirmed.
🌱 From Agronomy: Insights into pectin methylesterification show how cell wall chemistry and mechanics shape growth, stress tolerance, and crop quality, guiding targeted breeding strategies. (Isabel B. Ortega-Salazar, Barbara Blanco-Ulate)
▶️ www.mdpi.com/2073-4395/15...
#PlantScience #PlantBreeding