THE FIRST LAYER OF INNATE IMMUNITY IN PLANTS INVOLVES PERCEPTION OF PATHOGEN ASSOCIATED MOLECULAR PATTERNS (PAMPS) BY CELL SURFACE RECEPTORS, INCLUDING FLS2, A RECEPTOR FOR A FRAGMENT (FLG22 ) OF BACTERIAL FLAGELLIN. THE PURPOSE OF THIS STUDY IS TO DETERMINE THE POTENTIAL CROSSTALK BETWEEN THE PAMP RESPONSE TRIGGERED BY FLG22 AND THE PLANT PEPTIDE PHYTOSULFOKINE (PSK). THERE IS A KNOWN INTERACTION THESE TWO SIGNALING PATHWAYS, BUT THE MECHANISM IS NOT CLEAR. SPECIFICALLY, I WANT TO KNOW THE FOLLOWING: (1) DOES PSK/PSKR AFFECT THE INTERNALIZATION OF FLG22/FLS2? (2) HOW ARE THE SPATIAL TEMPORAL DYNAMICS OF FLG22/FLS2 INFLUENCED BY PSK AND ITS RECEPTORS (PSKR)? (3) IS THE DOWNSTREAM SIGNALING OF FLG22/FLS2 AFFECTED BY PSK/PSKR? TO ANSWER THESE QUESTIONS I WILL USE A VARIETY OF MUTANTS AND MICROSCOPY TECHNIQUES (TIRF &AMP; CONFOCAL) AS WELL AS RADIOLABELING TO TRACK THE DISTAL MOVEMENT OF FUNCTIONAL LABELED PEPTIDES. BIOSENSORS WILL BE USED TO MONITOR LEVELS OF CGMP AND CALCIUM PRODUCED IN MUTANT PLANTS IN RESPONSE TO LIGANDS. I WILL LOOK AT THE FUNCTIONAL INTERACTIONS BETWEEN FLG22 AND PSK PATHWAYS IN ARABIDOPSIS AND IN A CROP PLANT (RICE). THIS STUDY OFFERS A MEANS OF UNDERSTANDING HOW AN IMMUNE SIGNALING NETWORK IS MODULATED BY PAMPS AND PLANT SIGNALING PEPTIDES. WITH HIGH APPLICABILITY TO OTHER PLANT SPECIES, THE SYSTEM PRESENTED HERE COULD BE APPLIED TO OTHER SYSTEMS AND PROVIDE KNOWLEDGE OF DIFFERENT PATHWAYS THAT COULD HENCE BE OPTIMIZED FOR AGRICULTURE.