Pectin is a major cell wall component that plays important roles in plant development and response to environmental stresses. plants expressing a fungal polygalacturonase (PG plants) that degrades homogalacturonan (HG), a major pectin component, as well as loss-of-function mutants for (), encoding a putative pectin methyltransferase important for HG biosynthesis, show accumulation of reactive oxygen species (ROS), reduced growth and almost complete resistance to the fungal pathogen . Both PG and plants show increased expression of the class III peroxidase AtPRX71 that contributes to their elevated ROS levels and reduced growth. In this work, we show that leaves of PG and plants display greatly increased cuticle permeability. Both increased cuticle permeability and resistance to in are suppressed by loss of . Increased cuticle permeability in , rather than on defects in cuticle ultrastructure or cutin composition, appears to be dependent on reduced epidermal cell adhesion, which is exacerbated by , and is suppressed by the mutation, which also reverts the adhesion defect and the resistant phenotype. Increased cuticle permeability, accumulation of ROS, and resistance to are also observed in mutants lacking a functional FERONIA, a receptor-like kinase thought to monitor pectin integrity. In contrast, mutants with defects in other structural components of primary cell wall do not have a defective cuticle and are normally susceptible to the fungus. Our results suggest that disrupted cuticle integrity, mediated by peroxidase-dependent ROS accumulation, plays a major role in the robust resistance to of plants with altered HG integrity.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8415794 | PMC |
http://dx.doi.org/10.3389/fpls.2021.696955 | DOI Listing |
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