DET1 and DDB1 interact both biochemically and genetically. In animal cells, DDB1 interacts with histone acetyltransferase complexes. The DET1/DDB1 complex may regulate gene expression in response to light via recruitment of HAT activity. Thus, DET1, whose sequence is conserved in both animals and plants, may play a direct role in the regulation of many genes.

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The ability of plants to respond to environmental stimuli is essential to plant survival. Abscisic acid ABA is a phytohormone with roles at various stages of plant development. ABA also plays a major role in mediating physiological responses to environmental stresses such as salt, osmotic, and cold stress. Plant responses to environmental stress have been widely studied in the model plant Arabidopsis thaliana and ABA signaling mechanisms elucidated. In general, the adaptive responses of plants to various stress conditions can be either ABA-dependent or ABA-independent. Here we focus on the role of ABA in stress signaling and abiotic stress tolerance. We describe the intrinsic mechanisms that confer stress tolerance via ABA, as well as how ABA-regulated gene products play a role in salt and drought tolerance at different stages of the life cycle. In addition, the contribution of ABA to regulation of stomatal aperture and therefore desiccation tolerance will be discussed. Understanding ABA signaling mechanisms in abiotic stress provides avenues for improving plant performance.

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Damaged DNA Binding protein 1 (DDB1) is a conserved protein and a component of multiple cellular complexes. Arabidopsis has two homologues of DDB1: DDB1A and DDB1B. In this study we examine the role of DDB1A in Arabidopsis UV tolerance and DNA repair using a DDB1A null mutant (ddb1a) and overexpression lines. DDB1A overexpression lines showed higher levels of UV-resistance than wild-type in a range of assays as well as faster DNA repair. However a significant difference between wild-type plants and ddb1a mutants was only observed immediately following UV treatment in root length and photoproduct repair assays. DDB1A and DDB1B mRNA levels increased 3 h after UV exposure and DDB1A is required for UV regulation of DDB1B and DDB2 mRNA levels. In conclusion, while DDB1A is sufficient to increase Arabidopsis UV tolerance, it is only necessary for immediate response to UV damage.