Root and Shoot Growth of Plants Treated with Abscisic Acid

Watts, S. H.; Rodriguez, J. L.; Evans, Sarah E.; Davies, W. J.

doi:10.1093/oxfordjournals.aob.a086056

Cited by 102 publications

(71 citation statements)

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“…Control 14). The effects may be concentration related; in lower concentration, ABA may promote growth (15,23). In sunflower seedlings, ABA (10 MM) inhibits overall root growth (5) and extension (J. M. Robertson, unpublished data).…”

Section: Resultsmentioning

confidence: 99%

“…In most cases, water stress reduces root growth (3,5,7,16,23), although mild stress can increase extension (4,21,23). This is thought (4,21) to be the result of an osmoregulation process which preferentially maintains root growth during periods of water stress.…”

Section: Resultsmentioning

confidence: 99%

“…There is evidence for the involvement of ABA in some drought-associated developmental responses; several studies (5,9,18,23) have reported that the effects of exogenously applied ABA on plant development show similarities to the effects of water stress. Barlow and Pilet (1) have shown that exogenously applied ABA reduces cell division and DNA synthesis in the root apical meristem of corn.…”

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Drought-Induced Increases in Abscisic Acid Levels in the Root Apex of Sunflower

Robertson¹,

Pharis²,

Huang³

et al. 1985

Plant Physiol.

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Abscisic acid (ABA) levels in 3-mm apical root segments of slowly droughted sunflower plants (Helianthus annaus L. cv Russian Giant) were analyzed as the methyl ester by selected ion monitoring gas chromatogaphy-mass spectrometry using characteristic ions. An internal standard, hexadeuterated ABA (d6ABA) was used for quantitative analysis. Sunflower seedlings, grown in aeroponic chambers, were slowly droughted over a 7-day period. Drought stress increased ABA levels in the root tips at 24, 72, and 168 hour sample times. Control plants had 57 to 106 nanograms per gram ABA dry weight in the root tips (leaf water potential, -0.35 to -OA2 megapascals). The greatest increase in ABA, about 20-fold, was found after 72 hours of drought (leaf water potential, -1.34 to -1A7 megapascals). Levels of ABA also increased (about 7-to 54-fold) in 3-mm apical root segments which were excised and then allowed to dessicate for 1 hour at room temperature.Apart from its widely recognized role as an agent of stomatal closure, ABA may have other roles to play in the adaptation of plants to drought stress (8,17). The observations that ABA levels increase in the roots of water-stressed plants (7,11,12,19,22) and that this increase does not depend on transport from the shoot (19,22) are particularly provocative. Here, any action of ABA would not directly involve stomatal closure.There is evidence for the involvement of ABA in some drought-associated developmental responses; several studies (5, 9, 18, 23) have reported that the effects of exogenously applied ABA on plant development show similarities to the effects of water stress. Barlow and Pilet (1) have shown that exogenously applied ABA reduces cell division and DNA synthesis in the root apical meristem of corn. Ciamprova and Luxova (3) noted structural changes in the root apices of water-stressed maize plants. Earlier studies with sunflower seedlings found that drought stress inhibited root growth (5) and increased ABA levels in the root tissue (5,7). Changes in the anatomy of the root apices accompanied reduced growth in the droughted seedlings; moreover, the application of ABA (10 Mm) also inhibited root growth and induced anatomical changes at the root apices similar to those induced by drought (5).These observations suggest that the increases in ABA levels in droughted sunflower roots (7) may directly affect growth and development at the root apex where the developmental pattern by Sylvania Gro-Lux lamps (F72T12-GRO-WS-VHO) for 16 h each day at 25°C, followed by a dark period of 8 h at 16°C. Drought Regime. A time clock was attached to the electric motor which drives the spinner on one of the aeroponics chambers (7). Drought was imposed by withholding water for timed intervals; the seedlings were misted for 120 s h-' in two 60-s bursts for the first 24 h of treatment, then for 90 s h-' in one 60-s and one 30-s burst, thereafter. This droughting regime provided for a slow increase in water stress without subjecting the seedlings to a great initial shock at the beginning o...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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Drought-Induced Increases in Abscisic Acid Levels in the Root Apex of Sunflower

Robertson¹,

Pharis²,

Huang³

et al. 1985

Plant Physiol.

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“…Speculations on the involvement of ABA in growth responses to water stress have relied on the results of ABA applications to well-watered plants. Such applications have generally led to inhibition of shoot growth (1,5,11,28,29). In the case of roots, results have been variable; applications of ABA have resulted in growth inhibition (10,18,29), promotion (15,19,29), or have had little effect (5).…”

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confidence: 99%

“…Such applications have generally led to inhibition of shoot growth (1,5,11,28,29). In the case of roots, results have been variable; applications of ABA have resulted in growth inhibition (10,18,29), promotion (15,19,29), or have had little effect (5). In maize, applications of the hormone led to stimulation or inhibition of primary root growth depending on the initial root growth rate (19) and the concentration used (15,19), with higher concentrations being associated with growth inhibition.…”

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confidence: 99%

Increased Endogenous Abscisic Acid Maintains Primary Root Growth and Inhibits Shoot Growth of Maize Seedlings at Low Water Potentials

Saab¹,

Sharp²,

Pritchard³

et al. 1990

Plant Physiol.

369

218

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Roots of maize (Zea mays L.) seedlings continue to grow at low water potentials that cause complete inhibition of shoot growth. In this study, we have investigated the role of abscisic acid (ABA) in this differential growth sensitivity by manipulating endogenous ABA levels as an altemative to extemal applications of the hormone. An inhibitor of carotenoid biosynthesis (fluridone) and a mutant deficient in carotenoid biosynthesis (vp 5) were used to reduce the endogenous ABA content in the growing zones of the primary root and shoot at low water potentials. Experiments were performed on 30 to 60 hour old seedlings that were transplanted into vermiculite which had been preadjusted to water potentials of approximately -1.6 megapascals (roots) or -0.3 megapascals (shoots). Growth occurred in the dark at nearsaturation humidity. Results of experiments using the inhibitor and mutant approaches were very similar. Reduced ABA content by either method was associated with inhibition of root elongation and promotion of shoot elongation at low water potentials, compared to untreated and wild-type seedlings at the same water potential. Elongation rates and ABA contents at high water potential were little affected. The inhibition of shoot elongation at low water potential was completely prevented in fluridone-treated seedlings during the first five hours after transplanting. The results indicate that ABA accumulation plays direct roles in both the maintenance of primary root elongation and the inhibition of shoot elongation at low water potentials.A major reason behind the slow progress in the area of crop adaptation to drought is the insufficient basic understanding of the regulation of growth responses to water stress. When water is limited, shoot growth in many species is more inhibited than root growth (24), and in some cases, the absolute biomass of roots has been shown to increase relative to wellwatered controls (12,23). In maize, roots continue to grow at low water potentials that cause complete inhibition of shoot growth (25,30). The role of the hormone ABA in the differential growth responses of the primary root and shoot of maize to low water potentials is the subject of this paper.ABA accumulates to high concentrations in tissues ofplants

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