IN CUCUMBER, HYPOCOTYL ELONGATION IS INHIBITED BY LOW-DOSAGE UVB (LDUVB). THE HYPOCOTYL TENDS TO SHOW EXCESSIVE GROWTH IN GREENHOUSE ENVIRONMENTS DUE TO UV EXCLUSION OR HIGH TEMPERATURE. PROPER CONTROL OF HYPOCOTYL ELONGATION IS IMPORTANT IN LARGE-SCALE GREENHOUSE PRODUCTION SETTINGS WHERE STRONG SEEDLINGS ARE REQUIRED FOR TRANSPLANTATION. IN THIS PROJECT, WE AIM TO UNDERSTAND THE GENETIC CONTROL OF HYPOCOTYL ELONGATION IN CUCUMBER BY WORKING WITH TWO RECESSIVE MUTANTS, SHORT HYPOCOTYL1 (SH1) AND LONG HYPOCOTYL1 (LH1) THAT MODIFY HYPOCOTYL ELONGATION IN A LDUVB-INDEPENDENT MANNER. WE WILL INVESTIGATE THE GENETIC AND MOLECULAR MECHANISMS BY WHICH SH1- AND LH1-REGULATE HYPOCOTYL ELONGATION AND EXPLORE THE USE OF THE SH1 ALLELE IN CUCUMBER PRODUCTION. IN PARTICULAR, WE PLAN TO CLONE THE GENE LH1, AND INVESTIGATE THE STRUCTURE AND FUNCTION OF THE SH1 AND LH1 CANDIDATE GENES. WE ARE ALSO INTERESTED IN UNDERSTANDING THE REGULATORY NETWORK THAT SH1-/LH1-MEDIATED IN LDUVB-DEPENDENT HYPOCOTYL ELONGATION. FINALLY, WE WANT TO EXPLORE THE POTENTIAL USE OF THE SH1 GENE IN CUCUMBER PRODUCTION BY DEVELOPMENT AND EVALUATION OF GERMPLASM CARRYING THE SH1 ALLELE FOR USE IN CUCUMBER BREEDING. OUR LONG TERM GOALS IS TO USE UNTAPPED GENETIC DIVERSITY TO IMPROVE CUCUMBER PRODUCTIVITY IN VARIOUS ENVIRONMENTS, THUS CONTRIBUTING TO A MORE SUSTAINABLE AND PROFITABLE CUCUMBER INDUSTRY.