Histidine limitation alters plant development and influences the TOR network.

Plant growth depends on growth regulators, nutrient availability, and amino acids levels, all of which influence cell wall formation and cell expansion. Cell wall integrity and structures are surveyed and modified by a complex array of cell wall integrity sensors, including LRR-extensins (LRXs) that bind RALF (rapid alkalinization factor) peptides with high affinity and help to compact cell walls. Expressing the Arabidopsis root-hair specific LRX1 without the extensin domain, which anchors the protein to the cell wall, has a negative effect on root hair development.

Overlapping functions and protein-protein interactions of LRR-extensins in Arabidopsis.

Plant cell growth requires the coordinated expansion of the protoplast and the cell wall, which is controlled by an elaborate system of cell wall integrity (CWI) sensors linking the different cellular compartments. LRR-eXtensins (LRXs) are cell wall-attached extracellular regulators of cell wall formation and high-affinity binding sites for RALF (Rapid ALkalinization Factor) peptide hormones that trigger diverse physiological processes related to cell growth. LRXs function in CWI sensing and in the case of LRX4 of Arabidopsis thaliana, this activity was shown to involve interaction with the transmembrane Catharanthus roseus Receptor-Like Kinase1-Like (CrRLK1L) protein FERONIA (FER).