scholarly journals Integrated Transcriptome and Metabolome Analysis Reveals an Essential Role for Auxin in Hypocotyl Elongation during End-of-Day Far-Red Treatment of Cucurbita moschata (Duch. Ex Lam.)

Agronomy ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 853
Author(s):  
Qi Liu ◽  
Hanqing Zhang ◽  
Yanhao Mei ◽  
Qi Li ◽  
Yahui Bai ◽  
...  
Keyword(s):  
Essential Role ◽  
Parenchymal Cell ◽  
Red Light ◽  
Hypocotyl Elongation ◽  
Metabolome Analysis ◽  
Hypocotyl Length ◽  
Transport Inhibitor ◽  
Auxin Transport Inhibitor ◽  
Naphthylphthalamic Acid ◽  
Shed Light

Long, robust hypocotyls are important for facilitating greenhouse transplant production. The use of far-red light at the end of the day (end-of-day far-red, EOD-FR) is known to prompt hypocotyl elongation, but the mechanism of EOD-FR-mediated hypocotyl elongation in pumpkin remains unclear. Here, we found that hypocotyl length, parenchymal cell size in hypocotyls, and plant IAA levels were significantly greater in pumpkin after EOD-FR treatment. This effect was counteracted by the application of the polar auxin transport inhibitor 1-N-naphthylphthalamic acid. Integrated transcriptomic and metabolomic analysis of pumpkin hypocotyls revealed that the expression of auxin-related genes changed significantly after EOD-FR treatment, and the contents of the auxin biosynthetic precursors tryptophan and indole were also significantly higher. Our results show that auxin plays an essential role in EOD-FR-mediated hypocotyl elongation, shed light on the mechanisms of EOD-FR mediated hypocotyl elongation, and provide a theoretical basis for the use of EOD-FR in facility cultivation.

scholarly journals N-1-naphthylphthalamic acid stimulates tomato hypocotyl elongation, elevates ethylene levels and alters metabolic homeostasis

2018 ◽  
Author(s):  
Sapana Nongmaithem ◽  
Sameera Devulapalli ◽  
Yellamaraju Sreelakshmi ◽  
Rameshwar Sharma
Keyword(s):  
Butyric Acid ◽  
Metabolic Networks ◽  
Higher Plants ◽  
Red Light ◽  
Hypocotyl Elongation ◽  
Stimulated Emission ◽  
Ethylene Action ◽  
Naphthylphthalamic Acid ◽  
Exogenous Ethylene ◽  
Species Specific

One sentence summaryN-1-naphthylphthalamic acid (NPA) treatment stimulates tomato hypocotyl elongation likely by elevating ethylene emission and lowering indole-3-butyric acid levels in the seedlings.AbstractIn higher plants, phytohormone indole-3-acetic acid is characteristically transported from the apex towards the base of the plant, termed as polar auxin transport (PAT). Among the inhibitors blocking PAT, N-1-naphthylphthalamic acid (NPA) that targets ABCB transporters is most commonly used. NPA-treated light-grown Arabidopsis seedlings show severe inhibition of hypocotyl and root elongation. In light-grown tomato seedlings, NPA inhibited root growth, but contrary to Arabidopsis stimulated hypocotyl elongation. The NPA-stimulation of hypocotyl elongation was milder in blue, red, and far-red light-grown seedlings. The NPA-treatment stimulated emission of ethylene from the seedlings. The scrubbing of ethylene by mercuric perchlorate reduced NPA-stimulated hypocotyl elongation. NPA action on hypocotyl elongation was antagonized by 1-methylcyclopropene, an inhibitor of ethylene action. NPA-treated seedlings had reduced levels of indole-3-butyric acid and higher levels of zeatin in the shoots. NPA did not alter indole-3-acetic levels in shoots. The analysis of metabolic networks indicated that NPA-treatment induced moderate shifts in the networks compared to exogenous ethylene that induced a drastic shift in metabolic networks. Our results indicate that in addition to ethylene, NPA-stimulated hypocotyl elongation in tomato may also involve zeatin and indole-3-butyric acid. Our results indicate that NPA-mediated physiological responses may vary in a species-specific fashion.

Pitted morningglory (Ipomoea lacunosa) germination and emergence as affected by environmental factors and seeding depth

Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 910-916 ◽  
Author(s):  
Marcos J. Oliveira ◽  
Jason K. Norsworthy
Keyword(s):  
Red Light ◽  
Soil Surface ◽  
Moisture Stress ◽  
Hypocotyl Elongation ◽  
Burial Depth ◽  
Hypocotyl Length ◽  
Solution Ph ◽  
Wide Range ◽  
Pitted Morningglory ◽  
Ph Range

Laboratory and greenhouse experiments were conducted to determine the effect of light, temperature, solution pH, solution osmotic potential, and oxygen concentration on pitted morningglory germination and radicle plus hypocotyl elongation, and seeding depth on its subsequent emergence. Daily exposure of seed to natural light resulted in lower germination than in darkness, whereas germination was not influenced by brief exposure to red or far-red light. Germination occurred over a wide range of constant temperatures, from 7.5 to 52.5 C, with optimum germination between 20 and 25 C. Germination occurred at solution pH range of 3 to 10 and was optimal from pH 6 to 8. Radicle plus hypocotyl elongation was influenced by the interaction of temperature and solution pH. A combination of acidic medium (pH 6) and high temperature (30 C) resulted in the greatest radicle plus hypocotyl length of 7.6 cm after a 7-d incubation. Germination and radicle plus hypocotyl elongation, averaged over the 15 and 30 C temperature, decreased with increasing moisture stress, with less than 3% normalized germination at −1.0 MPa. Germination was 29, 40, and 51% at 2, 10, and 20% oxygen, respectively, averaged over 15 and 30 C. Germination of seed lying on the soil surface covered with filter paper or without any cover was similar, averaging 64%. Normalized emergence, relative to germination on the soil surface, decreased with increasing burial depth to 4% emergence at 10 cm, with a mean emergence depth of 4.1 cm, averaged across two soil types.

scholarly journals Integrated Analysis of the Transcriptome and Metabolomics Reveals an Essential Role for Auxin in Hypocotyl Elongation During End-of-Day Far-Red Treatment of Cucurbita Moschata

2020 ◽  
Author(s):  
Qi Liu ◽  
Hanqing Zhang ◽  
Yanhao Mei ◽  
Qi Li ◽  
Yahui Bai ◽  
...  
Keyword(s):  
Essential Role ◽  
Red Light ◽  
Cell Wall Protein ◽  
Hypocotyl Elongation ◽  
Integrated Analysis ◽  
Cucurbita Moschata ◽  
Plant Growth And Development ◽  
Auxin Synthesis ◽  
Important Regulator ◽  
Insight Into

Abstract BackgroundLong, robust hypocotyls are important for facilitating greenhouse transplant production. Use of far-red light at the end of the day (end-of-day far-red, EOD-FR) is known to affect hypocotyl elongation. Auxin is an important regulator of plant growth and development, but its role and mechanism in EOD-FR-mediated hypocotyl elongation remain unclear. Here we combined transcriptome sequencing and metabolite profiling of pumpkin hypocotyls with related physiological experiments to provide insight into the mechanisms by which auxin affects the response to EOD-FR. ResultsAfter EOD-FR treatment, the length of pumpkin Hypocotyl and the IAA level of plant Hypocotyl were significantly promoted. When NPA was applied, the Hypocotyl elongation mediated by EOD-FR and the increase of IAA content were counteracted.At the same time, through the observation of Hypocotyl sections, we found that hypocotyl cells expanded significantly after EOD-FR treatment.After EOD-FR treatment, 2801 DEGs, were identified in hypocotyl, of which 31 DEGs related to auxin synthesis, transport and signal transduction and 25 cell wall protein genes were identified.Through the detection of metabolic group, it was found that the levels of tryptophan and indole in plant increased after EOD-FR treatment.All these indicate that auxin plays an essential role in EOD-FR-mediated hypocotyl elongation.ConclusionsWe identified a large number of differentially expressed genes related to auxin synthesis, transport, and downstream response. We speculate that auxin is essential for pumpkin hypocotyl elongation mediated by EOD-FR, and that the synthesis of free IAA may be performed by the tryptophan-dependent TAA-YUC pathway. This study improves our understanding of auxin’s role in EOD-FR-mediated hypocotyl elongation.

scholarly journals End-of-day Far-red Light Quality and Dose Requirements for Tomato Rootstock Hypocotyl Elongation

HortScience ◽  
2010 ◽  
Vol 45 (10) ◽  
pp. 1501-1506 ◽  
Author(s):  
Po-Lung Chia ◽  
Chieri Kubota
Keyword(s):  
Light Quality ◽  
Dose Range ◽  
Red Light ◽  
Dry Weight ◽  
Light Dose ◽  
Hypocotyl Elongation ◽  
Type Model ◽  
Saturation Curve ◽  
Hypocotyl Length ◽  
Incandescent Light

Plant morphology control is a critical technique in commercial greenhouse transplant production. Light treatment at the end of the day affects a phytochrome-regulated response affecting plant height among other characteristics and has been studied by biologists for many years. Recognizing the need to produce long hypocotyls in vegetable grafting, effects of end-of-day far-red (EOD-FR) light on tomato rootstock hypocotyl elongation were investigated. Two commercial rootstock cultivars, Aloha (Solanum lycopersicum) and Maxifort (S. lycopersicum × S. habrochaites), were used for the experiments examining responses to EOD-FR light quality [red to far-red ratio (R/FR)] and EOD-FR light dose in a greenhouse environment. In the EOD-FR light quality experiment using ‘Aloha’ seedlings, incandescent light (R/FR = 0.47) induced significant hypocotyl elongation (20%) compared with the untreated control. Incandescent light with a spectral cut filter (reducing R/FR to 0.05) induced a greater hypocotyl elongation (44%) than unfiltered light, confirming the importance of use of light with a lower R/FR (or purer FR) light source in EOD-FR treatments. In the experiment on EOD-FR light dose–response, hypocotyl elongation of both ‘Aloha’ and ‘Maxifort’ was increased by increasing FR intensity as well as FR treatment duration at a lower dose range. The dose saturation curve of hypocotyl length was well described using a Michaelis-Menten-type model with FR dose (in mmol·m−2·d−1) as an independent variable. The model-based estimation of 90% saturating FR light dose for ‘Aloha’ and ‘Maxifort’ was 5 to 14 mmol·m−2·d−1 and 8 to 15 mmol·m−2·d−1, respectively, although practical near saturation dose seems to be 2 to 4 mmol·m−2·d−1 for both cultivars. None of the EOD-FR treatments affected plant dry weight, stem diameter, or plastochron index. Hence, elongation was achieved without compromising growth and development. EOD-FR was shown to be an effective non-chemical means allowing transplant propagation industry to produce long hypocotyls for grafting use.

scholarly journals Guard cells control hypocotyl elongation through HXK1, HY5, and PIF4

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Gilor Kelly ◽  
Danja Brandsma ◽  
Aiman Egbaria ◽  
Ofer Stein ◽  
Adi Doron-Faigenboim ◽  
...  
Keyword(s):  
Transcription Factors ◽  
Blue Light ◽  
Opposite Effect ◽  
Red Light ◽  
Guard Cells ◽  
Cell Types ◽  
Hypocotyl Elongation ◽  
Sugar Production ◽  
Effect Of Light

AbstractThe hypocotyls of germinating seedlings elongate in a search for light to enable autotrophic sugar production. Upon exposure to light, photoreceptors that are activated by blue and red light halt elongation by preventing the degradation of the hypocotyl-elongation inhibitor HY5 and by inhibiting the activity of the elongation-promoting transcription factors PIFs. The question of how sugar affects hypocotyl elongation and which cell types stimulate and stop that elongation remains unresolved. We found that overexpression of a sugar sensor, Arabidopsis hexokinase 1 (HXK1), in guard cells promotes hypocotyl elongation under white and blue light through PIF4. Furthermore, expression of PIF4 in guard cells is sufficient to promote hypocotyl elongation in the light, while expression of HY5 in guard cells is sufficient to inhibit the elongation of the hy5 mutant and the elongation stimulated by HXK1. HY5 exits the guard cells and inhibits hypocotyl elongation, but is degraded in the dark. We also show that the inhibition of hypocotyl elongation by guard cells’ HY5 involves auto-activation of HY5 expression in other tissues. It appears that guard cells are capable of coordinating hypocotyl elongation and that sugar and HXK1 have the opposite effect of light on hypocotyl elongation, converging at PIF4.

Auxin regulation of gibberellin biosynthesis in the roots of pea (Pisum sativum)

2009 ◽  
Vol 36 (4) ◽  
pp. 362 ◽  
Author(s):  
Diana E. Weston ◽  
James B. Reid ◽  
John J. Ross
Keyword(s):  
Pisum Sativum ◽  
Inhibitory Effect ◽  
Gibberellin Biosynthesis ◽  
Growth Inhibitory ◽  
Auxin Regulation ◽  
Auxin Transport Inhibitor ◽  
Naphthylphthalamic Acid ◽  
Pea Roots ◽  
High Auxin ◽  
Ga Biosynthesis

Auxin promotes GA biosynthesis in the aboveground parts of plants. However, it has not been demonstrated previously that this interaction occurs in roots. To understand the interactions between auxin and GAs in these organs, we treated wild-type pea (Pisum sativum L.) roots with the inhibitors of auxin action, p-chlorophenoxyisobutyric acid (PCIB) and yokonolide B (YkB), and with the auxin transport inhibitor N-1-naphthylphthalamic acid (NPA). These compounds generally downregulated GA synthesis genes and upregulated GA deactivation genes, and reduced the level of the bioactive GA1. These effects indicate that in pea roots, auxin at normal endogenous levels stimulates GA biosynthesis. We show also that supra-optimal levels of exogenous auxin reduce the endogenous level of bioactive GA in roots, although the effect appears too small to account for the strong growth-inhibitory effect of high auxin levels.

Role of mature leaves in inhibition of root bud growth inEuphorbia esulaL.

Weed Science ◽  
1999 ◽  
Vol 47 (5) ◽  
pp. 544-550 ◽  
Author(s):  
David P. Horvath
Keyword(s):  
Lateral Roots ◽  
Axillary Buds ◽  
Minor Effect ◽  
Correlative Inhibition ◽  
Auxin Transport Inhibitor ◽  
Naphthylphthalamic Acid ◽  
Bud Growth ◽  
A Minor ◽  
Root Buds

Earlier studies on the source of signals controlling correlative inhibition of root buds (underground adventitious buds located on the lateral roots) inEuphorbia esulaindicated that either growing meristems (apical or axillary buds) or fully expanded leaves could prevent root buds from breaking quiescence. An investigation of the production and transport requirements of the leaf-derived signal is described. As few as three leaves remaining on budless stems greatly reduced the growth of (but not the number of growing) root buds. Also, light and CO2fixation were necessary for the leaf effects on root bud growth, but not necessary for correlative inhibition imposed by growing axillary buds. Treatment of plants with Ametryn induced root bud growth on budless plants but not on plants with intact axillary buds. The polar auxin transport inhibitor N-1-naphthylphthalamic acid prevented transmission or the signal from growing axillary buds, but it had only a minor effect on the transmission of the leaf-derived signal. Treatment of plants with gibberellic acid (GA) induced growth of root buds under otherwise noninducing conditions to some extent in all plants. However, the greatest effects of GA were on plants with intact leaves (meristemless/budless and meristemless). GA had no significant effect on root bud quiescence under conditions that induced root bud growth.

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