The Arabidopsis thaliana Class III Peroxidase AtPRX71 Negatively Regulates Growth under Physiological Conditions and in Response to Cell Wall Damage.

Abstract

The structure of the cell wall has a major impact on plant growth and development, and alteration of cell wall structural components is often detrimental to biomass production. However, the molecular mechanisms responsible for these negative effects are largely unknown. Arabidopsis (Arabidopsis thaliana) plants with altered pectin composition because of either the expression of the Aspergillus niger polygalacturonase II (AnPGII; 35S:AnPGII plants) or a mutation in the QUASIMODO2 (QUA2) gene that encodes a putative pectin methyltransferase (qua2-1 plants), display severe growth defects. Here, we show that expression of Arabidopsis PEROXIDASE71 (AtPRX71), encoding a class III peroxidase, strongly increases in 35S:AnPGII and qua2-1 plants as well as in response to treatments with the cellulose synthase inhibitor isoxaben, which also impairs cell wall integrity. Analysis of atprx71 loss-of-function mutants and plants overexpressing AtPRX71 indicates that this gene negatively influences Arabidopsis growth at different stages of development, likely limiting cell expansion. The atprx71-1 mutation partially suppresses the dwarf phenotype of qua2-1, suggesting that AtPRX71 contributes to the growth defects observed in plants undergoing cell wall damage. Furthermore, AtPRX71 seems to promote the production of reactive oxygen species in qua2-1 plants as well as plants treated with isoxaben. We propose that AtPRX71 contributes to strengthen cell walls, therefore restricting cell expansion, during normal growth and in response to cell wall damage.

Oligosaccharides successfully thwart hijacking of the salicylic acid pathway by Phytophthora infestans in potato leaves

“…A cumulative stimulation of class III peroxidase activity, a well‐known PTI marker, was observed by both FytoSol and FytoSave, something already shown with FytoSave on tomato (van Aubel et al ., ). These enzymes actively take part in plant defence by stiffening cell walls, but class III peroxidases can also produce O2̇ − that dismutates into H 2 O 2 , thereby modifying the apoplastic ROS level and the whole cell redox homeostasis, notably through the redox‐sensitive protein NPR1 (Herrera‐Vásquez et al ., ; Raggi et al ., ).…”

Role of Reactive Oxygen Species during Cell Expansion in Leaves

“…In Arabidopsis, several POX genes have been linked to the regulation of cell expansion during leaf development. Plants overexpressing POX57 or POX71 show a reduced leaf size due to the accumulation of H 2 O 2 (Lu et al, 2014;Raggi et al, 2015). Interestingly, both POXs only affect cell expansion, but not proliferation, indicating that POXs might be specifically employed during the regulation of cell growth.…”

Plastid osmotic stress influences cell differentiation at the plant shoot apex

“…ROS accumulation has been documented in at least one other callusproducing mutant, tsd2/quasimodo2 (Raggi et al, 2015). Whether ROS and/or an ABA/GUN1/ABI4 retrograde signaling pathway are employed to communicate plastid dysfunction to shoot development in any of these other mutants is not known.…”