Functional ecology of a blue light photoreceptor: effects of phototropin‐1 on root growth enhance drought tolerance in <i>Arabidopsis thaliana</i>

Galen, Candace; Rabenold, Jessica J.; Liscum, Emmanuel

doi:10.1111/j.1469-8137.2006.01893.x

Cited by 97 publications

(79 citation statements)

References 31 publications

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“…In Arabidopsis hypocotyls, the photoreceptor phytochrome A mediates BL-induced inhibition of gravitropism (Lariguet and Fankhauser, 2004). Galen et al (2004Galen et al ( , 2007 demonstrated that phot1 is important for root penetration into the soil, which increased the drought tolerance of Arabidopsis seedlings. Our results show that all lines have similar gravitropic bending Shaded areas are based on the early hypothesis , while bright areas are based on our results to explain PIN2 localization and dynamics in darkness and under BL illumination.…”

Section: Discussionmentioning

confidence: 99%

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism

et al. 2012

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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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Section: Discussionmentioning

confidence: 99%

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism

et al. 2012

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“…The very low effective light fluence rates that act on tup5-1 indicate a physiological relevance and suggest an as yet unknown connection between amino acid biosynthesis, light perception, and root development. Roots contain red and blue light photoreceptors that may perceive light directly (Sakamoto and Briggs, 2002;Galen et al, 2007;Costigan et al, 2011;Dyachok et al, 2011, and references therein) and also respond to UV-B (Tong et al, 2008). Our genetic analyses have largely excluded several known components from light signaling pathways (CRY1, PHYB, HY2, and HY5) to operate in the TUP5 pathway, but not all known light receptors that could have a function in light perception by roots have been tested.…”

Section: Tup5-1 Mutants Show An Unusual Blue Light-dependent Root Gromentioning

confidence: 99%

“…Other candidate proteins include cry2, though cryptochrome effect on root elongation was perceived in the shoot according to a study of Canamero et al (2006). Phototropin phot1 was also found to have a role in blue light perception of the root where it mainly regulates directional growth (Galen et al, 2007;Kutschera and Briggs, 2012). phyA can absorb blue light and could thus also be a potential receptor in the signaling pathway regulating TUP5 (Lin, 2000).…”

Section: Tup5-1 Mutants Show An Unusual Blue Light-dependent Root Gromentioning

confidence: 99%

“…It is well documented that endogenous factors controlling root growth, such as phytohormones, are often regulated by exogenous signals, for example, by water and nutrient conditions (López-Bucio et al, 2003;Monshausen and Gilroy, 2009), as well as light (Canamero et al, 2006;Tong et al, 2008). There is evidence that roots contain different photoreceptors, that they are able to perceive light of different wavelengths, and that this regulates root functions (Sakamoto and Briggs, 2002;Canamero et al, 2006;Galen et al, 2007;Tong et al, 2008;Costigan et al, 2011;Dyachok et al, 2011, and references therein). However, a connection between light perception and the control of root development involving amino acid homeostasis as an influencing factor has not yet been reported.…”

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confidence: 99%

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The ArabidopsisTUMOR PRONE5Gene Encodes an Acetylornithine Aminotransferase Required for Arginine Biosynthesis and Root Meristem Maintenance in Blue Light

et al. 2013

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Arginine is an essential amino acid necessary for protein synthesis and is also a nitrogen storage compound. The genes encoding the enzymes of arginine biosynthesis in plants are not well characterized and have mainly been predicted from homologies to bacterial and fungal genes. We report the cloning and characterization of the TUMOR PRONE5 (TUP5) gene of Arabidopsis (Arabidopsis thaliana) encoding an acetylornithine aminotransferase (ACOAT), catalyzing the fourth step of arginine biosynthesis. The free arginine content was strongly reduced in the chemically induced recessive mutant tup5-1, root growth was restored by supplementation with arginine and its metabolic precursors, and a yeast (Saccharomyces cerevisiae) ACOAT mutant was complemented by TUP5. Two null alleles of TUP5 caused a reduced viability of gametes and embryo lethality, possibly caused by insufficient Arg supply from maternal tissue. TUP5 expression is positively regulated by light, and a TUP5-green fluorescent protein was localized in chloroplasts. tup5-1 has a unique light-dependent short root phenotype. Roots of light-grown tup5-1 seedlings switch from indeterminate growth to determinate growth with arresting cell production and an exhausted root apical meristem. The inhibitory activity was specific for blue light, and the inhibiting light was perceived by the root. Thus, tup5-1 reveals a novel role of amino acids and blue light in regulating root meristem function.

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“…4 Recently, blue light was shown to increase root growth and drought resistance of seedlings. 23 It is thus likely that light regulation of root development may be a common phenomenon important for seedling adaptation to environmental stress.…”

Section: Significance Of the Hy5-abi5 Regulon For Seedlings Under Abimentioning

confidence: 99%

Role of HY5 in abscisic acid response in seeds and seedlings

Chen

Xiong

2008

Plant Signaling & Behavior

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response in late embryogenesis-abundant (LEA) gene expression, seed germination, seedling establishment and root growth; (2) HY5 mediates these ABA responses partly by regulating the transcription of the seed/seedling-specific ABA signaling regulator ABI5, (3) ABA specifically enhances HY5 binding to the ABI5 chromatin and; (4) ABI5 sensitizes light repression of hypocotyl elongation. These results raise interesting questions on the interaction of light signaling and ABA signaling and its potential significance in plant response to the environment. HY5 Controls the Expression of ABI5 and ABI5-Targeted GenesThe Arabidopsis HY5 is a positive regulator of seedling photomorphogenesis downstream of diverse photoreceptors. 5-7 HY5 encodes a transcription factor of the basic leucine zipper (bZIP) domain family and controls the expression of many light-responsive genes. The ABI5 locus also encodes a bZIP transcription factor whose accumulation inhibits seed germination and early seedling establishment. 8,9 ABI5 is expressed during seed maturation, seed germination and young seedling stages. Its expression pattern partly overlaps with that of HY5. Both HY5 protein and ABI5 protein are also subjected to proteolysis during the early seedling stage. These observations suggest that HY5 regulation of ABI5 may occur within a restricted developmental window and that there must be other factors controlling the activation of ABI5 by HY5. Indeed, in tobacco BY-2 protoplasts, we did not find clear activation of ABI5 promoter-driven reporter gene by HY5. This indicates that seed or early seedling-specific factors such as ABI3, LEC1 and FUS3 9-13 are also needed for ABI5 activation. Among others, ABI3 was previously suggested to act upstream of ABI5. 11,14 Nonetheless, in our yeast two-hybrid assays, HY5 did not physically interact with ABI3 (Chen H and Xiong L, unpublished), suggesting that these two components may not be in physical contact with one another if they are within a common ABI5 transcriptional activation complex. Further identification of the components in this complex will be important for revealing the signaling network controlling seed development and seed germination.Similar to ABI5, the downstream target genes of ABI5 may also be tightly regulated. Recent microarray experiments with the abi5 as well as hy5 mutants have identified genes potentially regulated by these transcription factors (reviewed in refs. 15 and 16). However, the low level of transcript abundance for some of these genes in seedlings and the sensitivity of their regulation to developmental stages and tissue types make it difficult to interpret some of the data obtained in these microarray assays. While the transcript levels for Light affects many aspects of plant development including seed germination, phototropism, de-etiolation and flowering. 1 Light regulates these processes at least partly through its regulation of the metabolism and signal transduction of phytohormones. Experimental evidence has indicated that classic plant growth hormones, in...

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Functional ecology of a blue light photoreceptor: effects of phototropin‐1 on root growth enhance drought tolerance in Arabidopsis thaliana

Cited by 97 publications

References 31 publications

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism

The Signal Transducer NPH3 Integrates the Phototropin1 Photosensor with PIN2-Based Polar Auxin Transport in Arabidopsis Root Phototropism

The ArabidopsisTUMOR PRONE5Gene Encodes an Acetylornithine Aminotransferase Required for Arginine Biosynthesis and Root Meristem Maintenance in Blue Light

Role of HY5 in abscisic acid response in seeds and seedlings

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