**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** OUR PROPOSED FOUNDATIONAL RESEARCH PROJECT ADDRESSES A LONG-STANDING ENIGMA IN PLANTS, NAMELY HOW IMPORTANT HEALTH-PROTECTING, MEDICINAL, AND PLANT DEFENSE NATURAL PRODUCTS, KNOWN AS EITHER PROANTHOCYANIDINS (PAS) OR CONDENSED TANNINS ARE BIOSYNTHESIZED VIA COUPLING/POLYMERIZATION OF MONOMERIC FLAVONOIDS IN PLANTA. THIS RESEARCH IS A NIFA FOUNDATIONAL KNOWLEDGE OF PLANT PRODUCTS PROGRAM PRIORITY AREA, NAMELY STUDYING SYNTHESIS OF PLANT-DERIVED, HIGH VALUE CHEMICALS AND INGREDIENTS FOR USE IN FOODS, PHARMACEUTICALS, AND OTHER NATURAL PRODUCTS. WE PROPOSE THAT OUR RESEARCH WILL DETERMINE HOW BOTH HIGH THE VALUE GRAPE AND CRANBERRY CROPS BIOSYNTHESIZE THEIR PROANTHOCYANIDINS, CLASSIFIED AS TYPE B AND TYPE A PAS, RESPECTIVELY.WE DEDUCED THAT THE PROANTHOCYANIDIN FORMING BIOCHEMICAL MACHINERY IS IN A SUB-FAMILY OF THE LARGE DIRIGENT PROTEIN (DP) MULTI-GENE FAMILY WE DISCOVERED, WHICH WE HAVE NAMED AS PROANTHOCYANIDIN SYNTHASE/POLYMERASES (PASPS).WE WILL FIRST ESTABLISH HOW PA DIMER FORMATION OCCURS, AND WHETHER OR NOT ONLY PASPS ARE NEEDED, WITH STANDARD ACTIVITY ASSAYS AND PROTEIN PURIFICATION PROTOCOLS USING GRAPE/CRANBERRY TISSUES IF AND AS REQUIRED. PROANTHOCYANIDINS, HOWEVER, ALSO HAVE COVALENTLY LINKED EXTENDER UNITS, WHICH CAN INCREASE PA SIZE UP TO HETEROGENEOUS BIOPOLYMERS. YET, WE DO NOT KNOW HOW THEY ARE FORMED, OR WHAT COMPOSITIONS, MOLECULAR SIZE, OR CONTENTS ARE MOST EFFICACIOUS.ACCORDINGLY, WE WILL SEEK TO DETERMINE HOW OLIGOMERIZATION/POLYMERIZATION OCCURS AND WHETHER ADDITIONAL PROTEINS ARE INVOLVED. CRISPR/CAS9 TECHNOLOGIES WILL CONCOMITANTLY DETERMINE HOW GENE-EDITING PASPS (ALONE AND IN COMBINATION) DISRUPTS OR MODIFIES PA ACCUMULATION AND/OR CONTENT. OUR COLLABORATIONS WITH STANFORD SSRL AND PNNL EMSL RESEARCHERS ENABLE FULL CHARACTERIZATION OF THE PASPS AND ASSOCIATED PROTEINS, INCLUDING THEIR BIOCHEMICAL ASSEMBLY MECHANISMS, AS A KEY STEP IN STRATEGIC BIOTECHNOLOGICAL TAILORING OF PAS FOR OPTIMIZATION OF THEIR HEALTH-PROTECTING, MEDICINAL AND PLANT DEFENSE APPLICATIONS.