Post-Synthetic Reduction of Pectin Methylesterification Causes Morphological Abnormalities and Alterations to Stress Response in .

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 pectin methylesterase (AnPME) in plants to determine the impacts of methylesterification status on pectin function.

TOR mediates the autophagy response to altered nucleotide homeostasis in an RNase mutant.

The Arabidopsis thaliana T2 family endoribonuclease RNS2 localizes to the vacuole and functions in rRNA degradation. Loss of RNS2 activity impairs rRNA turnover and leads to constitutive autophagy, a process for degradation of cellular components. Autophagy is normally activated during environmental stress and is important for stress tolerance and homeostasis.

Dynamics of Autophagosome Formation.

Environmental stress activates autophagy and leads to autophagosome formation at the endoplasmic reticulum.

Regulation of autophagy through SnRK1 and TOR signaling pathways.

Autophagy is important for degradation and recycling of cytoplasmic materials in all eukaryotes and is often triggered by environmental stress. How autophagy is activated in plants under different environmental conditions is still poorly understood. Our recent studies show that induction of autophagy by different abiotic stress conditions can occur via either a TOR-dependent or -independent pathway, depending on the stress.

SnRK1 activates autophagy via the TOR signaling pathway in Arabidopsis thaliana.

Autophagy is a degradation process in which cells break down and recycle their cytoplasmic contents when subjected to environmental stress or during cellular remodeling. The Arabidopsis thaliana SnRK1 complex is a protein kinase that senses changes in energy levels and triggers downstream responses to enable survival. Its mammalian ortholog, AMPK, and yeast ortholog, Snf-1, activate autophagy in response to low energy conditions.

Degradation of the endoplasmic reticulum by autophagy during endoplasmic reticulum stress in Arabidopsis.

In this article, we show that the endoplasmic reticulum (ER) in Arabidopsis thaliana undergoes morphological changes in structure during ER stress that can be attributed to autophagy. ER stress agents trigger autophagy as demonstrated by increased production of autophagosomes. In response to ER stress, a soluble ER marker localizes to autophagosomes and accumulates in the vacuole upon inhibition of vacuolar proteases.