Under blue light (BL) illumination, Arabidopsis thaliana roots grow away from the light source, showing a negative phototropic response. However, the mechanism of root phototropism is still unclear. Using a noninvasive microelectrode system, we showed that the BL sensor phototropin1 (phot1), the signal transducer NONPHOTOTROPIC HYPOCOTYL3 (NPH3), and the auxin efflux transporter PIN2 were essential for BL-induced auxin flux in the root apex transition zone. We also found that PIN2-green fluorescent protein (GFP) localized to vacuole-like compartments (VLCs) in dark-grown root epidermal and cortical cells, and phot1/NPH3 mediated a BL-initiated pathway that caused PIN2 redistribution to the plasma membrane. When dark-grown roots were exposed to brefeldin A (BFA), PIN2-GFP remained in VLCs in darkness, and BL caused PIN2-GFP disappearance from VLCs and induced PIN2-GFP-FM4-64 colocalization within enlarged compartments. In the nph3 mutant, both dark and BL BFA treatments caused the disappearance of PIN2-GFP from VLCs. However, in the phot1 mutant, PIN2-GFP remained within VLCs under both dark and BL BFA treatments, suggesting that phot1 and NPH3 play different roles in PIN2 localization. In conclusion, BL-induced root phototropism is based on the phot1/NPH3 signaling pathway, which stimulates the shootward auxin flux by modifying the subcellular targeting of PIN2 in the root apex transition zone.
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http://dx.doi.org/10.1105/tpc.111.094284 | DOI Listing |
Sci Adv
August 2024
Institute of Plant and Microbial Biology, Academia Sinica, Taipei 11529, Taiwan.
The mechanisms of plant drought resistance are unclear but may involve membrane trafficking and metabolic reprogramming, including proline accumulation. Forward genetic screening using a () identified a drought hypersensitive mutant with a single-amino acid substitution (P335L) in the nonphototrophic hypocotyl 3 (NPH3) domain of NPH3/root phototropism 2-like 5 (NRL5)/naked pins in Yucca 8 (NPY8). Further experiments found that NRL5 and other NPH3 domain proteins are guanosine triphosphatases (GTPases).
View Article and Find Full Text PDFCommun Biol
January 2024
Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052, Ghent, Belgium.
Plant organs shift their directional growth in response to environmental stimuli through tropisms. Arabidopsis roots exhibit positive hydrotropism (towards water) and negative phototropism (away from light). In a recent study, Pang and colleagues demonstrated that root phototropism is regulated by the activity of two proteins in the elongation zone that also play essential roles in hydrotropism.
View Article and Find Full Text PDFStress Biol
December 2022
State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, Kaifeng, China.
To cope with fluctuating light conditions, terrestrial plants have evolved precise regulation mechanisms to help optimize light capture and increase photosynthetic efficiency. Upon blue light-triggered autophosphorylation, activated phototropin (PHOT1 and PHOT2) photoreceptors function solely or redundantly to regulate diverse responses, including phototropism, chloroplast movement, stomatal opening, and leaf positioning and flattening in plants. These responses enhance light capture under low-light conditions and avoid photodamage under high-light conditions.
View Article and Find Full Text PDFPlants (Basel)
August 2023
Department of Horticulture, Division of Applied Life Science (BK21 Four), Graduate School of Gyeongsang National University, Jinju 52828, Republic of Korea.
Nowadays, not only the roots, but also leaves and flowers of ginseng are increasingly popular ingredients in supplements for healthcare products and traditional medicine. The cultivation of the shade-loving crop, ginseng, is very demanding in terms of the light environment. Along with the intensity and duration, light direction is another important factor in regulating plant morphophysiology.
View Article and Find Full Text PDFPhysiol Mol Biol Plants
June 2023
School of Biological Science and Technology, University of Jinan, Jinan, 250022 China.
Unlabelled: Root systems anchor plants to the substrate in addition to transporting water and nutrients, playing a fundamental role in plant survival. The gene mediates gravity signal transduction and participates in root and shoot development and auxin flow in many plants. In this study, a regulator, LsLAZY1, was identified from based on previous transcriptome data.
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