Abstract
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.
Highlights
Various abiotic stress responses are induced by the signal of environmental stresses, for instance, drought, salinity, and high irradiance when plants suffer from adverse circumstances
Considering all these findings, we propose that MfPIF1 plays a positive regulatory role in resisting drought and salinity stresses in transgenic plants, which may give a reference to molecular breeding to endow plants with tolerance to abiotic stress
The cDNA sequence of MfPIF1 was cloned from M. flabellifolia by PCR amplification
Summary
Various abiotic stress responses are induced by the signal of environmental stresses, for instance, drought, salinity, and high irradiance when plants suffer from adverse circumstances. The WRKY, ZFP, bHLH, MYB, NAC, bZIP and DREB transcription factors (TFs) from various families play important roles in the gene regulatory network under unfavorable environments Overexpressing these stress-related genes in plants has demonstrated an enhanced tolerance to different abiotic stresses [6,7,8]. PIF1 can interact with two important regulatory proteins, HFR1 and LEUNIG_HOMOLOG, activate or inhibit the expression of downstream genes between the ABA and GA signaling pathways, and affect seed germination [35,36]. This indicates that PIF1 can regulate endogenous ABA biosynthesis and ABA signaling network. Considering all these findings, we propose that MfPIF1 plays a positive regulatory role in resisting drought and salinity stresses in transgenic plants, which may give a reference to molecular breeding to endow plants with tolerance to abiotic stress
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