Our lab’s focus is mainly centered on FERONIA (FER), the most studied member of a family of 17 transmembrane receptor kinases. FER along with LORELEI-like glycosylphosphatidylinositol- anchored protein 1 (LLG1) are crucial protagonists in regulating various signaling pathways regarding root growth, reproduction, and pathogen defense in Arabidopsis thaliana. The presence of malectin-like domains in the FER family and related receptor kinases are speculated to bind to carbohydrates cell wall components. Its malectin-like domains interact with pectin, a major carbohydrate polymer in the plant cell wall. These interactions have been linked to several major FER functions, including auxin- and RAC/ROP-mediated root hair growth and epidermal pavement cell patterning, and salt stress-induced cell growth responses (Feng et al., 2018). Both FER and LLG1 have been found to be co-receptors in mediating the release of reactive oxygen species (ROS) in female gametophyte and in a process where LLG1 acts as a chaperone protein and assists in transporting FERONIA from the endoplasmic reticulum to the cell membrane. This particular transportation is important as the extracellular domain of FER is a malectin-like domain containing receptor kinases in plants, homologous to the animal diglucose-binding protein malectin and important for protein quality control in the endoplasmic reticulum.
To further study the interaction with cell-wall polysaccharides potentially serving as wall-sensing functions, a study was conducted to better understand FER and LLG1 interactions with oligosaccharides (OG). As shown in the images, phenotypes for fer4 and llg 1-2 are very similar with a purple color in the dicotyledonous, first two leaves to sprout. Root Growth Assays were prepared with 14 day old seedling grown in 1/2MS agar solution of WT, fer4 and llg 1-2. Seedlings were scanned before treatment and two days after treatment with 1/2MS +OG. Seedlings for WT, fer4, and llg 1-2 were treated in these conditions: mock (only 1/2 MS) , [0.1] ½ MS+OG, and [.25] ½ MS+OG. Results confirmed that root growth inhibition occurs in the presence of OG and absence of fer4 kinase and llg 1-2 protein.