The Arabidopsis ARCP Protein, CSI1, Which Is Required for Microtubule Stability, Is Necessary for Root and Anther Development

Abstract

Armadillo repeat-containing proteins (ARCPs) are conserved across eukaryotic kingdoms and function in various processes. Regulation of microtubule stability by ARCPs exists widely in mammals and algae, but little is known in plants. Here, we present the functional characterization of an Arabidopsis thaliana ARCP, which was previously identified as Cellulose synthase-interactive protein1 (CSI1), and prove its crucial role in anther and root development. CSI1 is highly expressed in floral tissues, and knockout mutants of CSI1 (three allelic lines) accordingly exhibit defective anther dehiscence, which can be partially rescued by mammalian microtubule-stabilizer MAP4, suggesting that CSI1 functions by stabilizing the microtubular cytoskeleton. CSI1 binds microtubules in vitro, and immunofluorescence and coimmunoprecipitation studies confirmed the physical interactions between CSI1 and microtubules in vivo. Analysis using oryzalin, a microtubule-disrupting drug, further revealed the destabilized microtubules under CSI1 deficiency and confirmed the crucial role of CSI1 in microtubule stability. The dynamic change of CSI1 in response to dehydration strongly suggests the important function of CSI1 in dehydrationinduced microtubule depolymerization and reorganization, which is crucial for anther development. These results indicate the pivotal role of CSI1 in anther development by regulating microtubule stability and hence cell morphogenesis.

CESA TRAFFICKING INHIBITOR Inhibits Cellulose Deposition and Interferes with the Trafficking of Cellulose Synthase Complexes and Their Associated Proteins KORRIGAN1 and POM2/CELLULOSE SYNTHASE INTERACTIVE PROTEIN1

“…In addition, genetic lesions in pom2/csi1 null mutants exhibit both CSCs and cortical MT defects (Bringmann et al, 2012;Li et al, 2012;Mei et al, 2012;Landrein et al, 2013).…”

Proteomic Analysis of Microtubule Interacting Proteins over the Course of Xylem Tracheary Element Formation in Arabidopsis

“…During primary wall synthesis, microtubules directly guide cellulose synthesizing complexes via two microtubule interacting proteins, CELLULOSE SYNTHASE-INTERACTING PROTEIN1 (CSI1) and CSI3 Lei et al, 2013). CSI1 associates with microtubules Mei et al, 2012), with plasma membrane cellulose synthase complexes, as well as with the microtubule-associated cellulose synthase compartment (MASC) (Crowell et al, 2009;Bringmann et al, 2012), which may form part of the post-Golgi delivery system. Experimental modulation of CSI1 and CSI3 causes changes in both the tracking of cellulose synthase complexes along microtubules and their processivity (Bringmann et al, 2012;Lei et al, 2013), highlighting the tight link between microtubules and cell wall synthesis in primary walls.…”

Identification of miRNAs and their targets in wheat (Triticum aestivum L.) by EST analysis

“…MiR5067 and miR5175 targeted the nitrate transporter, and, in addition, miR5175 also targeted the ammonium transporter, whereas the transport protein particle component was identified as the targets of miR1439 and miR5175. Furthermore, several predicted targets were involved in plant development, where armadillo repeat-containing protein, proven to be critical for anther and root development in Arabidopsis thaliana (Mei et al, 2012), was predicted to be targeted by miR397. miR437 targeted C2 and GRAM domain proteins, which may play an important role during the late stage of pollen development and germination (Jiang et al, 2005).…”