RESUMO
The resurrection plants Myrothamnus flabellifolia can survive long term severe drought and desiccation conditions and soon recover after rewatering. However, few genes related to such excellent drought tolerance and underlying molecular mechanism have been excavated. WRKY transcription factors play critical roles in biotic and abiotic stress signaling, in which WRKY70 functions as a positive regulator in biotic stress response but a negative regulator in abiotic stress signaling in Arabidopsis and some other plant species. In the present study, the functions of a dehydration-induced MfWRKY70 of M. flabellifolia participating was investigated in the model plant Arabidopsis. Our results indicated that MfWRKY70 was localized in the nucleus and could significantly increase tolerance to drought, osmotic, and salinity stresses by promoting root growth and water retention, as well as enhancing the antioxidant enzyme system and maintaining reactive oxygen species (ROS) homeostasis and membrane-lipid stability under stressful conditions. Moreover, the expression of stress-associated genes (P5CS, NCED3 and RD29A) was positively regulated in the overexpression of MfWRKY70 Arabidopsis. We proposed that MfWRKY70 may function as a positive regulator for abiotic stress responses and can be considered as a potential gene for improvement of drought and salinity tolerance in plants.
Assuntos
Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Arabidopsis/genética , Magnoliopsida/genética , Tolerância ao Sal/genética , Fatores de Transcrição/metabolismo , Núcleo Celular/metabolismo , Biologia Computacional , Desidratação , Secas , Regulação da Expressão Gênica de Plantas , Homeostase , Membranas Artificiais , Osmose , Filogenia , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Espécies Reativas de Oxigênio , Salinidade , Sementes/metabolismo , Estresse Fisiológico , Fatores de Transcrição/genética , Água/químicaRESUMO
BACKGROUND: The basic helix-loop-helix (bHLH) proteins, a large transcription factors family, are involved in plant growth and development, and defensive response to various environmental stresses. The resurrection plant Myrothamnus flabellifolia is known for its extremely strong drought tolerance, but few bHLHs taking part in abiotic stress response have been unveiled in M. flabellifolia. RESULTS: In the present research, we cloned and characterized a dehydration-inducible gene, MfbHLH38, from M. flabellifolia. The MfbHLH38 protein is localized in the nucleus, where it may act as a transcription factor. Heterologous expression of MfbHLH38 in Arabidopsis improved the tolerance to drought and salinity stresses, as determined by the studies on physiological indexes, such as contents of chlorophyll, malondialdehyde (MDA), proline (Pro), soluble protein, and soluble sugar, water loss rate of detached leaves, reactive oxygen species (ROS) accumulation, as well as antioxidant enzyme activities. Besides, MfbHLH38 overexpression increased the sensitivity of stomatal closure to mannitol and abscisic acid (ABA), improved ABA level under drought stress, and elevated the expression of genes associated with ABA biosynthesis and ABA responding, sucha as NCED3, P5CS, and RD29A. CONCLUSIONS: Our results presented evidence that MfbHLH38 enhanced tolerance to drought and salinity stresses in Arabidopsis through increasing water retention ability, regulating osmotic balance, decreasing stress-induced oxidation damage, and possibly participated in ABA-dependent stress-responding pathway.
Assuntos
Aclimatação/genética , Arabidopsis/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/fisiologia , Magnoliopsida/genética , Proteínas de Plantas/fisiologia , Tolerância ao Sal/genética , Ácido Abscísico/metabolismo , Antioxidantes/metabolismo , Arabidopsis/fisiologia , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Núcleo Celular/fisiologia , Clonagem Molecular , DNA de Plantas , Secas , Regulação da Expressão Gênica de Plantas , Magnoliopsida/fisiologia , Proteínas de Plantas/genética , Estômatos de Plantas/fisiologia , Análise de Sequência de DNARESUMO
Phytochrome-interacting factors (PIFs), a subfamily of basic helix-loop-helix (bHLH) transcription factors (TFs), play critical roles in regulating plant growth and development. The resurrection plant Myrothamnus flabellifolia possesses a noteworthy tolerance to desiccation, but no PIFs related to the response to abiotic stress have been functionally studied. In this study, a dehydration-inducible PIF gene, MfPIF1, was cloned and characterized. Subcellular localization assay revealed that MfPIF1 is localized predominantly in the nucleus. Overexpression of MfPIF1 in Arabidopsis thaliana led to enhanced drought and salinity tolerance, which was attributed to higher contents of chlorophyll, proline (Pro), soluble protein, and soluble sugar, activities of antioxidant enzymes as well as lower water loss rate, malondialdehyde (MDA) content, and reactive oxygen species (ROS) accumulation in transgenic lines compared with control plants. Moreover, MfPIF1 decreased stomatal aperture after drought and abscisic acid (ABA) treatment, and increased expression of both ABA biosynthesis and ABA-responsive genes including NCED3, P5CS, and RD29A. Overall, these results indicated that MfPIF1 may act as a positive regulator to drought and salinity responses, and therefore could be considered as a potential gene for plant genetic improvement of drought and salinity tolerance.
