Cell Wall Integrity Controls Root Elongation via a General 1-Aminocyclopropane-1-Carboxylic Acid-Dependent, Ethylene-Independent Pathway  

Abstract

Cell expansion in plants requires cell wall biosynthesis and rearrangement. During periods of rapid elongation, such as during the growth of etiolated hypocotyls and primary root tips, cells respond dramatically to perturbation of either of these processes. There is growing evidence that this response is initiated by a cell wall integrity-sensing mechanism and dedicated signaling pathway rather than being an inevitable consequence of lost structural integrity. However, the existence of such a pathway in root tissue and its function in a broader developmental context have remained largely unknown. Here, we show that various types of cell wall stress rapidly reduce primary root elongation in Arabidopsis (Arabidopsis thaliana). This response depended on the biosynthesis of 1-aminocyclopropane-1-carboxylic acid (ACC). In agreement with the established ethylene signaling pathway in roots, auxin signaling and superoxide production are required downstream of ACC to reduce elongation. However, this cell wall stress response unexpectedly does not depend on the perception of ethylene. We show that the shortterm effect of ACC on roots is partially independent of its conversion to ethylene or ethylene signaling and that this ACCdependent pathway is also responsible for the rapid reduction of root elongation in response to pathogen-associated molecular patterns. This acute response to internal and external stress thus represents a novel, noncanonical signaling function of ACC.

Functional Phosphoproteomic Analysis Reveals That a Serine-62-Phosphorylated Isoform of Ethylene Response Factor110 Is Involved in Arabidopsis Bolting

“…The immediate ethylene biosynthesis precursor ACC has recently been suggested to play an ethyleneindependent biological role in plants (Tsang et al, 2011). However, the direct application of ethylene gas to wildtype and ein2-5 mutant plants in our experiments still resulted in a decrease in both the Ser-62-dephosphorylated isoform of ERF110 (Li et al, 2012) and kinase activity (or increased phosphatase activity) toward Ser-62 of ERF110 (Fig.…”

RICE SALT SENSITIVE3 binding to bHLH and JAZ factors mediates control of cell wall plasticity in the root apex

“…5,6 In addition, reduced root cell elongation and aberrant cell expansion are observed in the cobra mutant deficient in cellulose microfibril organization 7 or roots grown in the presence of isoxaben, a cellulose synthase inhibitor. 8 These observations raise the possibility that the rss3 mutant has a defect in the cell wall.…”

Producing the Ethylene Signal: Regulation and Diversification of Ethylene Biosynthetic Enzymes

“…Nonetheless, severe effects on seedling root growth should be expected for all of these inhibitors of ethylene synthesis, because reduced ethylene synthesis appears to be a primary defect in PLP-deficient roots, leading to impairments in auxin synthesis and distribution and in apical meristem function (Boycheva et al, 2015). Intriguingly, genetic analysis revealed an essential embryonic requirement for ACS function (but not ethylene signaling) in Arabidopsis (Arabidopsis thaliana; Tsuchisaka et al, 2009), and additional work has suggested that ACC may act in an ethylene-independent mode to signal loss of cell wall integrity (Xu et al, 2008;Tsang et al, 2011).…”