UNDERSTANDING OF THE FUNCTION OF RNA MOLECULES IN THE CELL HAS EVOLVED OVER THE PAST 25 YEARS AWAY FROM THE CLASSICAL VIEW OF RNA AS A SIMPLE MESSENGER MOLECULE THAT TRANSFERS INFORMATION BETWEEN DNA AND PROTEINS. MORE RECENTLY IT HAS BEEN SEEN THAT RNA, AND MORE SPECIFICALLY THE SECONDARY AND TERTIARY STRUCTURES THAT RNA SEQUENCES FOLD INTO IN LIVING CELLS, ARE DIRECTLY INVOLVED IN REGULATING GENE EXPRESSION AND OTHER BIOLOGICAL PROCESSES. THE FORMATION OF THESE COMPLEX RNA STRUCTURES IS GOVERNED BY INTERACTIONS WITH DIFFERENT BIOMOLECULES, INCLUDING IONS, RNA-BINDING PROTEINS AND EVEN OTHER RNA MOLECULES. CHANGES IN THE STRUCTURE OF AN RNA CAN CAUSE CHANGES IN CELLULAR FUNCTIONS. USING NOVEL RNA STRUCTURE PROBING TECHNIQUES, THIS RESEARCH WILL INVESTIGATE CHANGES IN THE STRUCTURES OF RNAS WITHIN A SPECIALIZED CELL TYPE IN PLANT LEAVES, CALLED GUARD CELLS, AS A RESULT OF ABSCISIC ACID TREATMENT. GUARD CELLS ARE FOUND IN THE SURFACES OF PLANT LEAVES AND REGULATE THE OPENING AND CLOSING OF STOMATA, WHICH ARE MICROSCOPIC PORES IN THE LEAF SURFACE THAT MEDIATE BOTH UPTAKE OF ATMOSPHERIC CARBON DIOXIDE, THE SUBSTRATE FOR PHOTOSYNTHESIS, AND WATER VAPOR LOSS FROM THE PLANT TO THE ATMOSPHERE. ABSCISIC ACID IS A PHYTOHORMONE PRODUCED BY THE PLANT IN RESPONSE TO ENVIRONMENTAL STRESSORS SUCH AS DROUGHT AND IS AN INTERNAL SIGNAL KNOWN TO REGULATE THE OPENING AND CLOSING OF STOMATA AND THEREFORE THE FUNCTIONING OF GUARD CELLS. THIS RESEARCH WILL IDENTIFY KEY RNA SEQUENCES THAT UNDERGO CHANGES IN STRUCTURE IN GUARD CELLS IN RESPONSE TO ABSCISIC ACID. THIS RESEARCH WILL BE PERFORMED IN CANOLA, AN AGRONOMICALLY VITAL SOURCE OF SEED OIL AND BIODIESEL. THE RNA SEQUENCES AND STRUCTURES IDENTIFIED IN THIS INVESTIGATION CAN BE UTILIZED AS GUARD-CELL SPECIFIC TARGETS FOR THE IMPROVEMENT OF CANOLA YIELD UNDER ENVIRONMENTAL STRESS.