RESUMO
The Arabidopsis (Arabidopsis thaliana) Early Light-Induced Protein (ELIP) is thought to act as a photoprotectant, reducing the damaging effects of high light (HL). Expression of ELIP2 is activated by multiple environmental stresses related to photoinhibition. We have identified putative regulatory elements in an ELIP2 promoter using an octamer-based frequency comparison method, analyzed the role of these elements using synthetic promoters, and revealed a key transcriptional regulatory unit for ultraviolet B (UV-B) radiation, HL, and cold stress responses. The unit is composed of two elements, designated as Elements A (TACACACC) and B (GGCCACGCCA), and shows functionality only when paired. Our genome-wide correlation analysis between possession of these elements in the promoter region and expression profiles in response to UV-B, HL, and cold suggests that Element B receives and integrates these multiple stress signals. In vitro protein-DNA binding assays revealed that LONG HYPOCOTYL5 (HY5), a basic domain-Leucine zipper transcription factor, directly binds to Element B. In addition, mutant analysis of HY5 showed partial involvement in the UV-B and HL responses but not in the cold stress response. These results suggest that signals for UV-B, HL, and cold stress join at Element B, which recognizes the signals of multiple transcription factors, including HY5.
Assuntos
Proteínas de Arabidopsis/genética , Temperatura Baixa , Regulação da Expressão Gênica de Plantas/efeitos da radiação , Regiões Promotoras Genéticas , Estresse Fisiológico/efeitos da radiação , Transcrição Gênica , Raios Ultravioleta , Arabidopsis/genética , Arabidopsis/efeitos da radiação , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Ritmo Circadiano/efeitos da radiação , Perfilação da Expressão Gênica , Luciferases/metabolismo , Modelos Genéticos , Proteínas Nucleares/metabolismo , Análise de Sequência com Séries de Oligonucleotídeos , Especificidade de Órgãos/genética , Ligação Proteica , Transcrição Gênica/efeitos da radiaçãoRESUMO
Hydrogen peroxide acts as a signaling molecule mediating the acquisition of tolerance to both biotic and abiotic stresses. Identification of marker genes for H2O2 response could help to intercept the signaling network of stress response of plants. Here, we describe application of marker genes for H2O2 responses to monitoring several abiotic stress responses. Arabidopsis plants were treated with UV-B, high light, and cold stresses, where involvement of H2O2-mediated signaling is known or suggested. Monitoring of these stress responses with molecular markers using quantitative real-time RT-PCR can detect landmark events in the sequential stress responses. These methods can be used for analysis of mutants and transgenic plants to examine natural H2O2 responses that are involved in environmental adaptation.
