ANALYSIS OF THE PLANT BIOLOGY TRANSCRIPTOMICS AND PROTEOMICS DATA IN THE GENELAB DATA SYSTEM REVEALS THAT A COMMON FEATURE OF SPACEFLIGHT IS ALTERATION IN PLANT DEFENSE-RELATED TRANSCRIPTS AND PROTEINS IN SPACE. ANECDOTALLY PLANTS HAVE ALSO BEEN SEEN TO SUFFER FROM PATHOGEN ATTACK DURING SPACEFLIGHT MISSIONS. TAKEN TOGETHER THESE OBSERVATIONS SUGGEST A HYPOTHESIS THAT PLANT DEFENSE RESPONSES MAY BE COMPROMISED BY SPACEFLIGHT. SUCH A DISRUPTION OF DEFENSE WOULD HAVE IMPORTANT IMPLICATIONS FOR THE MANAGEMENT OF PLANTS GROWN AS PART OF AN ASTRONAUT LIFE SUPPORT SYSTEM. THIS IS ESPECIALLY RELEVANT GIVEN THE LARGE MICROBIAL COMMUNITY ON BOARD THE ISS AND THE POSSIBILITY THAT SPACEFLIGHT TRIGGERS ENHANCED MICROBIAL PATHOGENICITY. HOWEVER THE CRITICAL UNANSWERED QUESTION IS WHETHER THE ALTERED DEFENSE GENE EXPRESSION SEEN IN SPACEFLIGHT TRULY PLAYS OUT AS ALTERED SUSCEPTIBILITY TO PATHOGENS. WE THEREFORE PROPOSE TO USE THE BRIC-LED HARDWARE GROWING ARABIDOPSIS SEEDLINGS TO DIRECTLY TEST THIS IDEA. SPECIFICALLY WE PROPOSE TO: (1) CAPITALIZE ON THE UNIQUE CAPABILITIES OF THE BRID-LED HARDWARE TO ANALYZE THE TRANSCRIPTOME AND CELL WALL STRUCTURE RESPONSES OF ARABIDOPSIS SEEDLINGS GROWN IN SPACEFLIGHT. WE PROPOSE TO GROW THESE PLANTS AND THEN CHALLENGE THEM WITH THE BACTERIAL ELICITOR PEPTIDE FLG22. WE WILL COMPARE THESE RESPONSES IN WILD-TYPE AND MUTANTS IN THE DEFENSE REGULATORS ATRBOHD AND CML24. (2) USE COMPARISONS TO GROUND-BASED CONTROL EXPERIMENTS AND CLINOSTAT AND HYPOXIA TREATMENT TO ASK WHETHER SUCH CHANGES ARE LIKELY LINKED TO THE MICROGRAVITY OR HYPOXIC ELEMENTS OF SPACEFLIGHT AND WHETHER THESE CHANGES MAY AFFECT THE ABILITY OF THE PLANT TO DEFEND ITSELF AGAINST PATHOGEN CHALLENGE. THE BRIC-LED/PDFU HARDWARE IS WELL-SUITED TO THIS EXPERIMENTAL APPROACH. THUS THE TWO-STAGE PDFU HARDWARE WILL ALLOW BOTH STIMULATION (INJECTION OF FLG22 ELICITOR ONTO THE SEEDLINGS) AND SUBSEQUENT FIXATION OF SAMPLES (WITH RNALATER). AS THE EXPERIMENT WOULD USE FLG22 PEPTIDE TO ELICIT DEFENSE RESPONSE POTENTIAL PROBLEMS WITH FLYING LIVE PATHOGEN WILL BE CIRCUMVENTED. THE EXPERIMENTAL DESIGN WILL CAPITALIZE ON THE MINIMAL CREW TIME NEEDED FOR A BRIC-BASED EXPERIMENT AND THE UNIQUE CAPABILITIES OF THE BRIC HARDWARE TO TREAT PLANTS IN SITU ON ORBIT. THE RESULTS FROM THIS EXPERIMENT WILL ALLOW US TO DIRECTLY ASK THE CRITICAL QUESTION OF WHETHER THE ABILITY OF PLANTS TO MOUNT A DEFENSE RESPONSE IS COMPROMISED DURING SPACEFLIGHT.