**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** THE WORLD'S POPULATION IS EXPECTED TO REACH 9.7 BILLION IN 2050. TO FEED THE EVER-INCREASING HUMAN POPULATION, GLOBAL CROP PRODUCTION MAY NEED TO BE INCREASED BY AT LEAST 50% BY 2050. TRADITIONAL BREEDING PLAYED AN IMPORTANT ROLE FOR DRAMATIC YIELD INCREASES DURING THE GREEN REVOLUTION. HOWEVER, ANNUAL YIELD GAINS FOR SEVERAL MAJOR STAPLE FOOD CROPS HAVE BEEN PLATEAUED IN THE PAST TWO DECADES. INCREASING CROP PRODUCTIVITY HAS BECOME THE MOST CHALLENGING ISSUE FACING AGRICULTURAL SCIENTISTS AND NEW TECHNOLOGICAL SOLUTIONS ARE NEEDED TO MEET THE GLOBAL DEMAND FOR CROP IMPROVEMENT. ONE SUCH STRATEGY THAT MAY HOLD UNTAPPED POTENTIAL FOR SUSTAINABLE YIELD INCREASES IS TO IMPROVE CROPS' PHOTOSYNTHETIC EFFICIENCY. ANOTHER POTENTIAL STRATEGY IS TO EXPLORE WILD SPECIES, AND IDENTIFY NOVEL, BUT OFTEN NEGLECTED GENES THAT CAN BE USED FOR THE ENHANCEMENT OF CROPS' RESILIENCE TO VARIOUS ENVIRONMENTAL STRESSES, AS WELL AS THE IMPROVEMENT OF YIELD AND QUALITY. THE LONG EFFORT IN PI'SLABORATORY IS TO EXPLORE PURSLANE (PORTULACA OLERACEA), A WILD SPECIES, FOR ITS POTENTIAL USE IN CROP IMPROVEMENT. RECENTLY, WE CLONED THE DRM2 HOMOLOGOUS GENE FROM PURSLANE (PODRM2). INTERESTINGLY, EXCEPT THE KNOWN CONSERVED DOMAINS, PODRM2 ALSO CONTAINS A UNIQUE CLFB DOMAIN AT ITS N TERMINAL THAT DOES NOT EXIST IN ALL OTHER AVAILABLE DRM2 HOMOLOGS. OVEREXPRESSION OF PODRM2 IN ARABIDOPSIS SIGNIFICANTLY INCREASED BIOMASS AND LEAF STARCH ACCUMULATION. IN ADDITION, THE PODRM2 TRANSGENIC LINE SIGNIFICANTLY INCREASED CHLOROPHYLL CONTENT SUGGESTING A ROLE OF PODRM2 IN REGULATING PHOTOSYNTHESIS. DRM2 ACTS AS MAJOR DNA METHYLTRANSFERASE AND IS ESSENTIAL FOR RNA-DIRECTED DE NOVO DNA METHYLATION OF CYTOSINE. BASED ON OUR PRELIMINARY RESEARCH AND THE ROLE OF DRM2 IN DNA METHYLATION, WE HYPOTHESIZE THAT PODRM2 REGULATES STARCH ACCUMULATION AND BIOMASS PRODUCTION THROUGH EPIGENETIC REGULATING PLANT PHOTOSYNTHESIS. TO TEST THIS HYPOTHESIS, WE WILL GENERATE TRANSGENIC SOYBEAN AND CORN LINES OVEREXPRESSING PODRM2 AND EXAMINE THEIR PHOTOSYNTHESIS-RELATED TRAITS. IN ADDITION, WE WILL ALSO SYSTEMICALLY INVESTIGATE MOLECULAR MECHANISMS AND GENE NETWORKS REGULATING PODRM2 MEDIATED EPIGENETIC CONTROL OF PLANT PHOTOSYNTHESIS. THIS PROJECT ADDRESSES THE FUNDAMENTAL ISSUE OF CROP PRODUCTION-CROP PHOTOSYNTHESIS, AND WOULD GENERATE BASIC KNOWLEDGES ON EPIGENETIC CONTROL OF PLANT PHOTOSYNTHETIC EFFICIENCY.