Journal of Experimental Botany, Vol. 53, No. 366, pp. 33-37,
January 1, 2002
© 2002 Oxford University Press
Short Papers |
ABA, ethylene and the control of shoot and root growth under water stress
Department of Agronomy, Plant Sciences Unit, 1–87 Agriculture Building, University of Missouri, Columbia, MO 65211, USA
Received 19 September 2001; Accepted 25 September 2001
Abstract
The question of whether abscisic acid (ABA) acts as an inhibitor or promoter of shoot growth in plants growing in drying soil is examined, drawing on current understanding of the role of ABA in root growth maintenance. Particular consideration is given to studies of endogenous ABA deficiency, which have shown that an important role of ABA is to limit ethylene production, and that this interaction is involved in the effects of ABA status on shoot and root growth.
Key words: Abscisic acid, ethylene, root growth, shoot growth, water stress.
Introduction
Shoot growth is more sensitive than root growth to soil drying (Sharp and Davies, 1989
), and can be inhibited prior to the development of decreased water potentials in the aerial parts of the plant (Saab and Sharp, 1989; Gowing et al., 1990). This response is thought to be attributable to the action of non-hydraulic regulatory signals from those roots exposed to dry soil, while at the same time the remainder of the root system supplies adequate water to maintain the shoot water status. There has been considerable attention given to the possibility that root-sourced abscisic acid (ABA) is at least partly the cause of shoot growth inhibition under these circumstances. However, definitive evidence is lacking and, by contrast, recent studies of ABA-deficient mutants suggest that endogenous ABA may often function to maintain rather than inhibit shoot growth. Drawing on current understanding of the role of ABA in root growth regulation at low water potentials, this review considers the circumstances under which ABA may act as an inhibitor or promoter of shoot growth in water-stressed plants, in particular regarding its involvement in long-distance signalling from the roots.
Recent advances
For almost 25 years, there has been much speculation that the increase in concentration of abscisic acid (ABA) in water-stressed plants may be causally related to growth inhibition, particularly of shoot growth (Quarrie and Jones, 1977; Trewavas and Jones, 1991). This view has arisen largely because of the typically inhibitory effect of ABA on shoot and root growth when it has been applied to well-watered plants. In some such experiments, the resulting relationship between the ABA content of the tissues or xylem sap and growth inhibition suggested that the increase in endogenous ABA in water-stressed plants was sufficient to account for much if not all of the inhibition of growth that resulted from the water stress treatment (Creelman et al., 1990; Zhang and Davies, 1990). However, in roots of maize seedlings, it has been demonstrated that such observations do not predict the function of endogenous ABA accumulation during water stress. As shown in Fig. 1, root elongation was inhibited progressively in well-watered seedlings when the root tip ABA content (encompassing the elongation zone) was increased by applying a range of ABA concentrations. The relationship is consistent with the possibility that the level of ABA in the roots of seedlings growing under water stress is responsible for the inhibition of root elongation in these seedlings. However, when the ABA content of the water-stressed roots was decreased chemically (using the inhibitor fluridone) or genetically (using the vp5 or vp14 mutants), elongation was further inhibited rather than increased. Root elongation recovered when the ABA content was restored with exogenous ABA, confirming that the normal accumulation of endogenous ABA is in fact necessary for root growth maintenance during water stress. It is important to emphasize that these experiments were performed under conditions of near-zero transpiration (darkness, near-saturation humidity, minimal shoot development), and therefore the effect of ABA deficiency on root growth was not confounded by indirect effects due to variation in stomatal control of plant water status.
|
w) (-0.03 MPa, open symbols) or low water potential (-1.6 MPa, closed symbols). At high water potential, the root ABA content of hybrid (cv. FR27xFRMo17) seedlings was raised above the normal level by adding various concentrations of ABA (A) to the vermiculite. At low water potential, the root ABA content was decreased below the normal level by treatment with fluridone (F) or by using the vp5 or vp14 mutants. Data are plotted as a percentage of the rate for the same genotype at high water potential. Elongation rates of the mutants at high water potential were similar to their respective wild types (from Sharp, 2001In ABA-deficient seedlings under water stress, the rate of ethylene production was greatly increased (Fig. 2
), and this effect was completely prevented when normal ABA levels were restored (Spollen et al., 2000). Moreover, root elongation of ABA-deficient seedlings recovered to the control rate when ethylene production was reduced to normal levels using inhibitors of ethylene synthesis, showing that an important role of endogenous ABA accumulation in the maintenance of root elongation at low water potentials is to prevent excess ethylene production. The discovery that increased ABA levels are required to limit ethylene production in water-stressed plants confirms ideas first suggested by Wright (Wright, 1980), but which had not been tested. Importantly, when the increase in ethylene production was prevented, ABA deficiency had no effect on root elongation (Fig. 2). Thus, the interaction of ABA with ethylene did not override an opposing growth-inhibitory role of ABA accumulation in the response of root elongation to water stress. From this work, it appears that the inhibitory effect of applied ABA on root growth of well-watered seedlings does not provide useful information about the function of ABA in the regulation of root growth during water stress.
|
How do these findings relate to the role of increased ABA concentrations in the response of shoot growth to water stress? As already mentioned, there are many reports that applied ABA is a potent inhibitor of shoot growth in well-watered plants. However, only one series of reports in the literature has shown that ABA deficiency in plants under water stress (or, in fact, under any stress condition) causes improvement of shoot growth, as would be expected if endogenous ABA accumulation is actually a cause of growth inhibition. Under water stress, the rate of shoot elongation was greater in ABA-deficient (fluridone-treated or vp5 mutant) maize seedlings than in the control (Saab et al., 1990
, 1992; Sharp et al., 1994). Additional work with the same system, however, showed that the promotive effect of ABA deficiency on shoot growth was restricted to the early post-germination stage and that, in fact, the response subsequently reversed such that ABA deficiency caused further growth inhibition, as in roots. Moreover, treatment with supplemental ABA resulted in a substantial promotion of shoot growth at the later time compared to control seedlings (Fig. 3; Feng, 1996; Sharp, 2001). This effect was not observed in the roots (Fig. 3; Sharp et al., 1994), indicating that one reason shoot growth was more inhibited than root growth during water stress was because ABA levels were optimal for root elongation but were insufficient for maximal elongation of the shoot.
|
Further experiments indicated that the effects of ABA status on shoot growth were attributable to a similar antagonistic interaction with ethylene to that described above for root growth (Feng, 1996
; Sharp, 2001). The results suggest that ABA was growth inhibitory in very young seedlings because ethylene was growth promotive during that stage of development, whereas ABA subsequently became growth promotive because ethylene became growth inhibitory. Moreover, because of the insufficiency of endogenous ABA accumulation, ethylene was a significant cause of the inhibition of shoot growth in water-stressed seedlings at the later stages of development. This contrasts to the roots, in which the normal accumulation of ABA was sufficient to prevent ethylene-induced growth inhibition (Spollen et al., 2000).
If restriction of ethylene production is a widespread function of ABA, then ABA may, more generally, play a role in shoot growth promotion rather than inhibition, because ethylene is usually inhibitory to the shoot growth of terrestrial plants (Abeles et al., 1992). In support of this idea, recent studies have established that the impaired shoot growth of ABA-deficient mutants of tomato (Sharp et al., 2000) and Arabidopsis (ME LeNoble, WG Spollen and RE Sharp, unpublished data) under well-watered conditions is at least partly attributable to excess ethylene production (rather than to adverse plant water relations as had previously been believed). Also, studies by Roberts et al. indicate that increased ABA concentrations help to maintain rather than inhibit the shoot growth of plants subjected to soil compaction (Roberts et al., 2002). In barley, it was demonstrated that shoot growth inhibition was greater in the ABA-deficient mutant Az34 than in the wild type (Mulholland et al., 1996a, b). Also, by using ethylene-deficient transgenic plants, it was demonstrated that excess ethylene production was a major cause of shoot growth inhibition in wild-type tomato plants (Hussain et al., 1999). Further, treatment with supplemental ABA (applied to the soil) partly reduced shoot ethylene production and partly restored shoot growth in the wild-type plants (Hussain et al., 2000). Thus, as in the water-stressed maize seedlings described above, the normal levels of ABA in the plants subjected to soil compaction appeared to be insufficient to prevent excess ethylene production in the shoot. Interestingly, in the ethylene-deficient transgenic plants, xylem ABA levels were increased to the same extent as in the wild type (2-fold in response to compaction, and 4-fold with the supplemental ABA treatment), yet shoot growth was almost the same as in plants grown without compaction. In other words, ethylene-deficiency did not uncover an inhibitory effect of increased ABA concentrations on shoot growth, similar to the above-described situation in water-stressed roots.
It is not known whether endogenous ABA functions to restrict synthesis of the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC) or the conversion of ACC to ethylene, or both. This information is important for understanding the involvement of the ABA–ethylene interaction in root-to-shoot signalling in stressed plants. In the case of soil compaction, only the roots directly experienced the stress condition. In response to mechanical impedance it is known that roots exhibit increased production of ACC and ethylene, and that ethylene is a cause of root growth inhibition (Sarquis et al., 1991, 1992). Accordingly, the excess synthesis of ethylene in the shoots of plants growing in compacted soil may be attributable to an insufficiency of ABA in the roots, leading to the increased export of ACC to the shoot. Such a scenario is also likely in plants exposed to soil flooding, in which it has been shown that the ABA concentration in roots decreases substantially (probably because of the oxygen-requiring steps in ABA synthesis) and the ACC concentration in xylem sap increases greatly (Jackson, 2002). On the other hand, in the studies of water-stressed maize seedlings, ABA accumulated to high levels in the roots, and this was sufficient to prevent ethylene-induced inhibition of root growth. Since the whole seedlings were at low water potentials, it seems likely that the ethylene-induced inhibition of shoot growth resulted from insufficiency of ABA within the shoots themselves.
Issues for the future
Taken together, the findings with water-stressed maize seedlings, compaction-stressed barley and tomato, and well-watered tomato and Arabidopsis indicate that restriction of ethylene production is a common function of endogenous ABA. In stressed tissues, however, it appears that a greater tendency for ethylene production necessitates elevated levels of ABA to prevent ethylene-induced growth inhibition.
Is there any situation where increased ABA concentrations in water-stressed plants might exert the inhibitory effect on shoot growth predicted from the effects of applying ABA to well-watered plants? Conceivably, this might occur under the conditions described at the beginning of this review where plants are growing in drying soil but with unchanged shoot water status. Bacon et al. demonstrated that, in wild-type barley, growth of excised leaves from well-watered plants was inhibited when they were fed artificial xylem sap with a raised pH to simulate the known effect of soil drying (Bacon et al., 1998). The growth inhibition is thought to result from an increase in the concentration of ABA in the apoplast, and did not occur in the ABA-deficient mutant Az34 unless a normal well-watered concentration of ABA was supplied in the sap. However, it remains to be tested whether ABA-deficient intact plants actually exhibit less inhibition of shoot growth than control plants when growing under such conditions in drying soil.
The design and interpretation of such experiments will be challenging for several reasons. First, if plants with ABA-deficient roots as well as shoots are studied, ACC export from the roots may increase, resulting in ethylene-induced inhibition of shoot growth that could override any improvement of growth that might otherwise have occurred. This difficulty could be resolved by examining the effects of ABA deficiency in ethylene-deficient or ethylene-insensitive plants. Second, because of the adverse effect of ABA deficiency on stomatal behaviour and hence shoot water status, interpretation of growth responses of ABA-deficient compared to control genotypes might be confounded by indirect effects of differing water status. Therefore, experimental strategies to circumvent variation in water status between genotypes should be employed (Sharp et al., 2000; Sharp, 2001). Third, impaired shoot and root growth of well-watered control plants, as is often the case for ABA-deficient mutants, may also confound the interpretation of growth responses to ABA deficiency under stress. In such plants, it may not be possible to distinguish the role of stress-induced increases in ABA concentration from the function of normal ABA levels. For example, Hussain et al. attempted to use the ABA-deficient notabilis mutant of tomato to demonstrate that wild-type ABA concentrations are important in maintaining shoot growth of plants growing in compacted soil by limiting ethylene production (Hussain et al., 2000), as would be predicted from the above-described promotive effect of supplemental ABA in this system. However, the mutant actually exhibited less inhibition of shoot growth and a similar rate of leaf ethylene evolution compared to the wild type. It seems likely that these results were attributable, respectively, to the increase in ethylene with compaction exerting a greater effect on shoot growth of the previously uninhibited wild type, and to the smaller root system of the mutant (Sharp et al., 2000), which would have lessened the amount of roots exposed to compacted soil and, consequently, limited the ACC signal to the shoot.
To avoid the problem of impaired growth of well-watered control plants, a partially complemented line of the notabilis mutant has recently been identified which exhibits normal ABA levels and growth when well watered, yet is deficient in ABA accumulation under water stress (ET Thorne, AC Jackson, A Burbidge, AJ Thompson, IB Taylor, RE Sharp, unpublished data). This genotype is being used to examine the role of increased ABA concentrations in the response of shoot growth to soil drying both under conditions of whole plant water stress and when the shoot water status is maintained.
Conclusions
Recent studies show that increased concentrations of ABA are required to prevent excess ethylene production from tissues under water stress. As a result, ABA accumulation during water stress may often function to help maintain shoot as well as root growth, rather than to inhibit growth as is commonly believed. It is also possible that ABA acts to inhibit shoot growth in drying soil under conditions where shoot water deficits do not occur, but this remains to be demonstrated.
Acknowledgments
This work was supported by award no. 95-37100-1601 from the NRI Competitive Grants Program/US Department of Agriculture and by the University of Missouri Food for the 21st Century Program. This is contribution No. 13181 from the Missouri Agricultural Experiment Station Journal Series.
Notes
1 To whom correspondence should be addressed. Fax: +1 573 882 1469. E-mail: SharpR{at}missouri.edu 
References
Abeles FB, Morgan PW, Saltveit Jr ME. 1992. Ethylene in plant biology, 2nd edn. San Diego: Academic Press.
Bacon MA, Wilkinson S, Davies WJ. 1998. pH-regulated leaf cell expansion in droughted plants is abscisic acid dependent. Plant Physiology 118, 1507–1515.
Creelman RA, Mason HS, Bensen RJ, Boyer JS, Mullet JE. 1990. Water deficit and abscisic acid cause differential inhibition of shoot versus root growth in soybean seedlings. Analysis of growth, sugar accumulation and gene expression. Plant Physiology 92, 205–214.
Feng X. 1996. Is ABA an inhibitor or promoter of shoot growth in water-stressed plants? MS thesis, University of Missouri, Columbia, USA.
Gowing DJG, Davies WJ, Jones HG. 1990. A positive root-sourced signal as an indicator of soil drying in apple, Malusxdomestica Borkh. Journal of Experimental Botany 41, 1535–1540.
Hussain A, Black CR, Taylor IB, Roberts JA. 1999. Soil compaction. A role for ethylene in regulating leaf expansion and shoot growth in tomato? Plant Physiology 121, 1227–1237.
Hussain A, Black CR, Taylor IB, Roberts JA. 2000. Does an antagonistic relationship between ABA and ethylene mediate shoot growth when tomato (Lycopersicon esculentum Mill.) plants encounter compacted soil? Plant, Cell and Environment 23, 1217–1226.
Jackson M. 2002. Long-distance signalling from roots to shoots assessed: the flooding story. Journal of Experimental Botany 53, (in press).
Mulholland BJ, Black CR, Taylor IB, Roberts JA, Lenton JR. 1996a. Effect of soil compaction on barley (Hordeum vulgare L.) growth. I. Possible role for ABA as a root-sourced chemical signal. Journal of Experimental Botany 47, 539–549.
Mulholland BJ, Taylor IB, Black CR, Roberts JA. 1996b. Effect of soil compaction on barley (Hordeum vulgare L.) growth. II. Are increased xylem sap ABA concentrations involved in maintaining leaf expansion in compacted soils? Journal of Experimental Botany 47, 551–556.
Quarrie SA, Jones HG. 1977. Effects of abscisic acid and water stress on development and morphology of wheat. Journal of Experimental Botany 28, 192–203.
Roberts JA, Hussain A, Taylor IB, Black CR. 2002. Use of mutants to study long-distance signalling in response to compacted soil. Journal of Experimental Botany 53, 45–50.
Saab IN, Sharp RE. 1989. Non-hydraulic signals from maize roots in drying soil: inhibition of leaf elongation but not stomatal conductance. Planta 179, 466–474.
Saab IN, Sharp RE, Pritchard J. 1992. Effect of inhibition of ABA accumulation on the spatial distribution of elongation in the primary root and mesocotyl of maize at low water potentials. Plant Physiology 99, 26–33.
Saab IN, Sharp RE, Pritchard J, Voetberg GS. 1990. Increased endogenous abscisic acid maintains primary root growth and inhibits shoot growth of maize seedlings at low water potentials. Plant Physiology 93, 1329–1336.
Sarquis, JI, Jordan WR, Morgan PW. 1991. Ethylene evolution from maize (Zea mays L.) seedling roots and shoots in response to mechanical impedance. Plant Physiology 96, 1171–1177.
Sarquis JI, Morgan PW, Jordan WR. 1992. Metabolism of 1-aminocyclopropane-1-carboxylic acid in etiolated maize seedlings grown under mechanical impedance. Plant Physiology 98, 1342–1348.
Sharp RE. 2001. Interaction with ethylene: changing views on the role of ABA in root and shoot growth responses to water stress. Plant, Cell and Environment (in press).
Sharp RE, Davies WJ. 1989. Regulation of growth and development of plants growing with a restricted supply of water. In: Jones HG, Flowers TL, Jones MB, eds. Plants under stress. Cambridge: Cambridge University Press, 71–93.
Sharp RE, LeNoble ME, Else MA, Thorne ET, Gherardi F. 2000. Endogenous ABA maintains shoot growth in tomato independently of effects on plant water balance: evidence for an interaction with ethylene. Journal of Experimental Botany 51, 1575–1584.
Sharp RE, Wu Y, Voetberg GS, Saab IN, LeNoble ME. 1994. Confirmation that abscisic acid accumulation is required for maize primary root elongation at low water potentials. Journal of Experimental Botany 45, 1743–1751.
Spollen WG, LeNoble ME, Samuels TD, Bernstein N, Sharp RE. 2000. Abscisic acid accumulation maintains maize primary root elongation at low water potentials by restricting ethylene production. Plant Physiology 122, 967–976.
Trewavas AJ, Jones HG. 1991. An assessment of the role of ABA in plant development. In: Davies WJ, Jones HG, eds. Abscisic acid: physiology and biochemistry. Oxford: Bios Scientific Publishers, 169–188.
Wright STC. 1980. The effect of plant growth regulator treatments on the levels of ethylene emanating from excised turgid and wilted wheat leaves. Planta 148, 381–388.
Zhang J, Davies WJ. 1990. Does ABA in the xylem control the rate of leaf growth in soil-dried maize and sunflower plants? Journal of Experimental Botany 41, 1125–1132.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  M. Okamoto, Y. Tanaka, S. R. Abrams, Y. Kamiya, M. Seki, and E. Nambara High Humidity Induces Abscisic Acid 8'-Hydroxylase in Stomata and Vasculature to Regulate Local and Systemic Abscisic Acid Responses in Arabidopsis Plant Physiology, February 1, 2009; 149(2): 825 - 834. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Albacete, M. E. Ghanem, C. Martinez-Andujar, M. Acosta, J. Sanchez-Bravo, V. Martinez, S. Lutts, I. C. Dodd, and F. Perez-Alfocea Hormonal changes in relation to biomass partitioning and shoot growth impairment in salinized tomato (Solanum lycopersicum L.) plants J. Exp. Bot., November 1, 2008; 59(15): 4119 - 4131. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. Wasilewska, F. Vlad, C. Sirichandra, Y. Redko, F. Jammes, C. Valon, N. F. d. Frey, and J. Leung An Update on Abscisic Acid Signaling in Plants and More ... Mol Plant, March 1, 2008; 1(2): 198 - 217. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. V. Kurepin, R. J. N. Emery, R. P. Pharis, and D. M. Reid Uncoupling light quality from light irradiance effects in Helianthus annuus shoots: putative roles for plant hormones in leaf and internode growth J. Exp. Bot., June 1, 2007; 58(8): 2145 - 2157. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. J. Burke Evaluation of Source Leaf Responses to Water-Deficit Stresses in Cotton Using a Novel Stress Bioassay Plant Physiology, January 1, 2007; 143(1): 108 - 121. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Rosado, A. L. Schapire, R. A. Bressan, A. L. Harfouche, P. M. Hasegawa, V. Valpuesta, and M. A. Botella The Arabidopsis Tetratricopeptide Repeat-Containing Protein TTL1 Is Required for Osmotic Stress Responses and Abscisic Acid Sensitivity Plant Physiology, November 1, 2006; 142(3): 1113 - 1126. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Okamoto, A. Kuwahara, M. Seo, T. Kushiro, T. Asami, N. Hirai, Y. Kamiya, T. Koshiba, and E. Nambara CYP707A1 and CYP707A2, Which Encode Abscisic Acid 8'-Hydroxylases, Are Indispensable for Proper Control of Seed Dormancy and Germination in Arabidopsis Plant Physiology, May 1, 2006; 141(1): 97 - 107. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. E. Verslues and E. A. Bray Role of abscisic acid (ABA) and Arabidopsis thaliana ABA-insensitive loci in low water potential-induced ABA and proline accumulation J. Exp. Bot., January 1, 2006; 57(1): 201 - 212. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C.-W. Chen, Y.-W. Yang, H.-S. Lur, Y.-G. Tsai, and M.-C. Chang A Novel Function of Abscisic Acid in the Regulation of Rice (Oryza sativa L.) Root Growth and Development Plant Cell Physiol., January 1, 2006; 47(1): 1 - 13. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Park, J. Li, J. K. Pittman, G. A. Berkowitz, H. Yang, S. Undurraga, J. Morris, K. D. Hirschi, and R. A. Gaxiola Up-regulation of a H+-pyrophosphatase (H+-PPase) as a strategy to engineer drought-resistant crop plants PNAS, December 27, 2005; 102(52): 18830 - 18835. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Y. Liang and J. M. Harris Response of root branching to abscisic acid is correlated with nodule formation both in legumes and nonlegumes Am. J. Botany, October 1, 2005; 92(10): 1675 - 1683. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. M. Barrero, P. Piqueras, M. Gonzalez-Guzman, R. Serrano, P. L. Rodriguez, M. R. Ponce, and J. L. Micol A mutational analysis of the ABA1 gene of Arabidopsis thaliana highlights the involvement of ABA in vegetative development J. Exp. Bot., August 1, 2005; 56(418): 2071 - 2083. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. Y. Sobeih, I. C. Dodd, M. A. Bacon, D. Grierson, and W. J. Davies Long-distance signals regulating stomatal conductance and leaf growth in tomato (Lycopersicon esculentum) plants subjected to partial root-zone drying J. Exp. Bot., November 1, 2004; 55(407): 2353 - 2363. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. Ruggiero, H. Koiwa, Y. Manabe, T. M. Quist, G. Inan, F. Saccardo, R. J. Joly, P. M. Hasegawa, R. A. Bressan, and A. Maggio Uncoupling the Effects of Abscisic Acid on Plant Growth and Water Relations. Analysis of sto1/nced3, an Abscisic Acid-Deficient but Salt Stress-Tolerant Mutant in Arabidopsis Plant Physiology, October 1, 2004; 136(2): 3134 - 3147. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. DaCosta, Z. Wang, and B. Huang Physiological Adaptation of Kentucky Bluegrass to Localized Soil Drying Crop Sci., July 1, 2004; 44(4): 1307 - 1314. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
W. Fricke, G. Akhiyarova, D. Veselov, and G. Kudoyarova Rapid and tissue-specific changes in ABA and in growth rate in response to salinity in barley leaves J. Exp. Bot., May 1, 2004; 55(399): 1115 - 1123. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Koiwai, K. Nakaminami, M. Seo, W. Mitsuhashi, T. Toyomasu, and T. Koshiba Tissue-Specific Localization of an Abscisic Acid Biosynthetic Enzyme, AAO3, in Arabidopsis Plant Physiology, April 1, 2004; 134(4): 1697 - 1707. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. E. LeNoble, W. G. Spollen, and R. E. Sharp Maintenance of shoot growth by endogenous ABA: genetic assessment of the involvement of ethylene suppression J. Exp. Bot., January 2, 2004; 55(395): 237 - 245. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Reymond, B. Muller, A. Leonardi, A. Charcosset, and F. Tardieu Combining Quantitative Trait Loci Analysis and an Ecophysiological Model to Analyze the Genetic Variability of the Responses of Maize Leaf Growth to Temperature and Water Deficit Plant Physiology, February 1, 2003; 131(2): 664 - 675. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. M. CHAVES, J. S. PEREIRA, J. MAROCO, M. L. RODRIGUES, C. P. P. RICARDO, M. L. OSORIO, I. CARVALHO, T. FARIA, and C. PINHEIRO How Plants Cope with Water Stress in the Field? Photosynthesis and Growth Ann. Bot., June 15, 2002; 89(7): 907 - 916. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||