The TOR pathway modulates the structure of cell walls in Arabidopsis.
Plant cell growth is limited by the extension of cell walls, which requires both the synthesis and rearrangement of cell wall components in a controlled fashion. The target of rapamycin (TOR) pathway is a major regulator of cell growth in eukaryotes, and inhibition of this pathway by rapamycin reduces cell growth. Here, we show that in plants, the TOR pathway affects cell wall structures. LRR-extensin1 (LRX1) of Arabidopsis thaliana is an extracellular protein involved in cell wall formation in root hairs, and lrx1 mutants develop aberrant root hairs. rol5 (for repressor of lrx1) was identified as a suppressor of lrx1. The functionally similar ROL5 homolog in yeast, Ncs6p (needs Cla4 to survive 6), was previously found to affect TOR signaling. Inhibition of TOR signaling by rapamycin led to suppression of the lrx1 mutant phenotype and caused specific changes to galactan/rhamnogalacturonan-I and arabinogalactan protein components of cell walls that were similar to those observed in the rol5 mutant. The ROL5 protein accumulates in mitochondria, a target of the TOR pathway and major source of reactive oxygen species (ROS), and rol5 mutants show an altered response to ROS. This suggests that ROL5 might function as a mitochondrial component of the TOR pathway that influences the plant's response to ROS.
University of Zürich, Institute of Plant Biology, 8008 Zurich, Switzerland.
Ruth-Maria
RM
Leiber
Florian
F
John
Yves
Y
Verhertbruggen
Anouck
A
Diet
J Paul
JP
Knox
Christoph
C
Ringli
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010641:Phenotype; D018517:Plant Roots / Q000166:cytology; D012343:RNA, Transfer / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology
D029681:Arabidopsis Proteins; D018744:DNA, Plant; C427476:LRX1 protein, Arabidopsis; D017382:Reactive Oxygen Species; D012343:RNA, Transfer; D020123:Sirolimus