Graduate Student Auburn University Auburn, Alabama
Body of Abstract: Cytokinin Response Factors (CRFs) are a subset of the plant specific AP2/ERF domain transcription factors. CRFs were originally identified as having a role of cytokinin (CK) regulation of leaf/cotyledon development, but many studies also have also linked CRFs to various abiotic stressors, such as oxidative, cold, and salt. Here we expand these examinations to evaluate effects of heat stress responses in CRFs and if CK can delay this abiotic stress induced senescence in Arabidopsis. Specifically, the role of 11 different isoforms of CK including the bases [cis-Zeatin (cZ), trans-zeatin (tZ), Isopentyl adenine (iP) and Dihydrozeatin (DHZ)] and their corresponding glucose N-conjugates were assayed if they could delay leaf senescence. Mature (32 days old) detached leaves of Arabidopsis thaliana and altered CRF expression lines (mutants and overexpression lines) were studied at heat stress conditions (370C). The effect of different CK isoform treatments on delaying leaf senescence was measured by determining PSII efficiency (Fv/Fm) and total chlorophyll content. We found that the base forms tZ, cZ and iP have a significant impact on delaying heat stress. Therefore, the results suggest that CK plays a significant role delaying leaf senescence in WT and altered CRF lines when exposed to heat stress. This preliminary data should be aimed at showing novel genes involving CK regulation and their effect towards the heat stress in Arabidopsis thaliana.