Post-Synthetic Reduction of Pectin Methylesterification Causes Morphological Abnormalities and Alterations to Stress Response in <i>Arabidopsis thaliana</i>
Nathan T. Reem,
Lauran Chambers,
Ning Zhang,
Siti Farah Abdullah,
Yintong Chen,
Guanhua Feng,
Song Gao,
Junmarie Soto-Burgos,
Gennady Pogorelko,
Diane C. Bassham,
Charles T. Anderson,
Justin W. Walley,
Olga A. Zabotina
Affiliations
Nathan T. Reem
Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
Lauran Chambers
Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
Ning Zhang
Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
Siti Farah Abdullah
Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
Yintong Chen
Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
Guanhua Feng
Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
Song Gao
Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, USA
Junmarie Soto-Burgos
Department of Genetics, Development & Cell Biology, Iowa State University, Ames, IA 50011, USA
Gennady Pogorelko
Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
Diane C. Bassham
Department of Genetics, Development & Cell Biology, Iowa State University, Ames, IA 50011, USA
Charles T. Anderson
Department of Biology, The Pennsylvania State University, University Park, PA 16802, USA
Justin W. Walley
Department of Plant Pathology & Microbiology, Iowa State University, Ames, IA 50011, USA
Olga A. Zabotina
Department of Biochemistry, Biophysics, and Molecular Biology, Iowa State University, Ames, IA 50011, USA
Pectin is a critical component of the plant cell wall, supporting wall biomechanics and contributing to cell wall signaling in response to stress. The plant cell carefully regulates pectin methylesterification with endogenous pectin methylesterases (PMEs) and their inhibitors (PMEIs) to promote growth and protect against pathogens. We expressed Aspergillus nidulans pectin methylesterase (AnPME) in Arabidopsis thaliana plants to determine the impacts of methylesterification status on pectin function. Plants expressing AnPME had a roughly 50% reduction in methylester content compared with control plants. AnPME plants displayed a severe dwarf phenotype, including small, bushy rosettes and shorter roots. This phenotype was caused by a reduction in cell elongation. Cell wall composition was altered in AnPME plants, with significantly more arabinose and significantly less galacturonic acid, suggesting that plants actively monitor and compensate for altered pectin content. Cell walls of AnPME plants were more readily degraded by polygalacturonase (PG) alone but were less susceptible to treatment with a mixture of PG and PME. AnPME plants were insensitive to osmotic stress, and their susceptibility to Botrytis cinerea was comparable to wild type plants despite their compromised cell walls. This is likely due to upregulated expression of defense response genes observed in AnPME plants. These results demonstrate the importance of pectin in both normal growth and development, and in response to biotic and abiotic stresses.
