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Steudle, Ernst

doi:10.1023/a:1026439226716

Cited by 369 publications

(80 citation statements)

References 66 publications

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“…In the absence of transpiration, water moves cell-to-cell by osmotic forces through semipermeable membranes; membranes provide a variable resistance to water flow depending on the abundance and activity of aquaporins or water channel proteins. Steudle (1) postulated that the two pathways interact with each other and that such interactions are responsible for regulating the circulation of water in the plant. The results presented here support such an interaction: when the stomates were wide open, as in the aba1 and abi plants, the P os of the protoplasts was found to be very low, much lower than in control plants that had partially opened stomates; when the stomates were closed because ABA had been added to the growth medium, the P os increased more than 10-fold.…”

Section: Discussionmentioning

confidence: 99%

“…Water that moves through living tissues can follow an apoplastic or cell-to-cell path. Careful measurements of the hydraulic properties of plant tissues and organs show that the relative contribution of each pathway to overall hydraulic conductivity may change substantially depending on the intensity of water flow and other factors (1). When the rate of water flow is high (open stomates, low relative humidity), water flows along the apoplast and around the protoplasts because the apoplastic path has the lower hydraulic resistance.…”

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confidence: 99%

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The role of ABA and the transpiration stream in the regulation of the osmotic water permeability of leaf cells

Morillón

Chrispeels

2001

Proc. Natl. Acad. Sci. U.S.A.

142

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The transpiration stream that passes through a plant may follow an apoplastic route, with low resistance to flow, or a cell-to-cell route, in which cellular membranes impede water flow. However, passage of water through membranes can be facilitated by aquaporins thereby decreasing resistance. We investigated the relationship between transpiration, which can be down-regulated by abscisic acid (ABA) or by high humidity, and the osmotic water permeability (P os) of protoplasts. By using leaf protoplasts of wild-type (wt) Arabidopsis thaliana plants and of mutants that are low in ABA (aba1) or insensitive to ABA (abi1 and abi2), we found that protoplasts from aba1 and abi mutants have very low P os values compared with those from wt plants when the plants are grown at 45% relative humidity. High values of P os were found 3 h after the addition of ABA to the culture medium of aba1 plants; addition of ABA to abi plants did not restore the P os to wt levels. There was no such increase in P os when excised leaves of aba1 plants were treated with ABA. When the transpiration stream was attenuated by growing the plants at 85% relative humidity, the P os of protoplasts from all plants (wt and mutants) was higher. We suggest that attenuation of the transpiration stream in whole plants is required for the up-regulation of the P os of the membranes, and that this up-regulation, which does not require ABA, is mediated by the activation of aquaporins in the plasma membrane. P lant growth requires a tradeoff between the need to acquire CO 2 for photosynthesis and the need to minimize water loss from the leaves. Water lost through the transpiration stream is replaced by water that is taken up from the soil. The force that drives this water uptake is the tension created by the evaporation of water from the leaf cells. Water that moves through living tissues can follow an apoplastic or cell-to-cell path. Careful measurements of the hydraulic properties of plant tissues and organs show that the relative contribution of each pathway to overall hydraulic conductivity may change substantially depending on the intensity of water flow and other factors (1). When the rate of water flow is high (open stomates, low relative humidity), water flows along the apoplast and around the protoplasts because the apoplastic path has the lower hydraulic resistance. Conversely, when the rate of water flow is small, a larger proportion of water follows the cell-to-cell path and needs to pass through cellular membranes (and possibly through plasmodesmata). Water flow along this path has a much higher hydraulic resistance and can be modulated by aquaporins, proteins that facilitate transmembrane water transport (2-4). An important unanswered question is whether the magnitude of flow in the apoplastic path affects the resistance in the cell-to-cell path.In plants, aquaporins form a family of 35-37 sequence-related proteins (5, 6) that transport water and neutral solutes, such as glycerol, across membranes. Aquaporins have been found in the tonoplast (vacuol...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

The role of ABA and the transpiration stream in the regulation of the osmotic water permeability of leaf cells

Morillón

Chrispeels

2001

Proc. Natl. Acad. Sci. U.S.A.

142

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“…For some cells, NaCl may be considered as a non-permeant species and eq is close to unity (Steudle and Henzler, 1995). Reflection coefficients smaller than unity were measured previously on entire roots for nutrient salts such as KCl and KNO 3 , but even in this case, cells were assumed to behave as perfect osmometers, the reduction in being explained by the lower reflection coefficient of parallel pathways (Steudle, 2000). In the stomata and pulvinar cells, KCl is the main osmoticum and the water flux induced by Equation 2 will remain small as long as the variations in ⌬ can be neglected.…”

Section: Rt V Wmentioning

confidence: 98%

Rapid Movements of Plants Organs Require Solute-Water Cotransporters or Contractile Proteins

Morillón

2001

Plant Physiology

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“…Changes in K r and L p are related to root structure and anatomy. Suberization and the formation of Casparian bands in the endo-and exodermis of roots impede transport along the apoplastic pathway, thus contributing to a lower L p of whole root system (Steudle 2000). Increase in K r is connected to the growth in the number and diameter of xylem vessels in Lupinus species (Bramley et al 2009).…”

Section: Water Relations and Gas Exchangementioning

confidence: 99%

Effect of waterlogging on boreal forest tree seedlings during dormancy and early growing season

Wang¹

2017

Diss. For.

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More precipitation in the form of rain in winter together with deteriorated ditch networks may expose drained peatland forestry to winter or spring waterlogging in boreal forests. The response of main boreal forest species on soil waterlogging is important for predicting forest productivity and justifying the demand for ditch network maintenance. In this study, the aim was to find out the physiological and growth responses of 1-year-old Norway spruce (Picea abies (L.) Karst.), silver birch (Betula pendula Roth) and pubescent birch (Betula pubescens Ehrh.) seedlings subjected to one-month waterlogging at the end of the dormancy phase, and to find out the morphology, physiology and growth of silver birch and pubescent birch seedlings subjected to one-month waterlogging at the beginning of the growing season.Two experiments were carried out in growth chambers. In experiment 1, Norway spruce seedlings were subjected to either no waterlogging or waterlogging for one month at 2 o C, after which a six-week follow-up growing season allowed the seedlings to recover. In experiment 2, silver birch and pubescent birch seedlings went through a four-week dormancy (weeks 1-4), a four-week early growing season (weeks 5-8), and a four-week late growing season (weeks 9-12). The treatments were 1) no waterlogging throughout the experiment (NW); 2) four-week waterlogging during dormancy (Dormancy waterlogging, DW); 3) four-week waterlogging during the early growing season (Growth waterlogging, GW); and 4) four-week dormancy waterlogging followed by four-week growth waterlogging during the early growing season (DWGW).Dormancy waterlogging reduced root volume and increased root mortality, but did not affect dark-acclimated chlorophyll fluorescence (F v /F m ) or the biomass of leaves, stems and roots in Norway spruce. Root biomass and root hydraulic conductance (K r ) of silver birch was reduced but aboveground organs were not affected by dormancy waterlogging. On the contrary, in pubescent birch root morphology, biomass and K r were not affected, but gas exchange was reduced by dormancy waterlogging. However, the biomass of leaves and stems was not negatively affected in pubescent birch. In conclusion, these tree species can tolerate a one-month winter waterlogging well.Growth waterlogging led to the reduction of stomatal conductance (g s ), and thus the reduction of light-saturated photosynthesis rate (A max ) in both birch species, although recovery was seen during the follow-up growing season. It also led to lower leaf area in both birch species. Growth waterlogging led also to decreased the K, Ca, Mg, Mn and B contents of leaves in silver birch, whereas in pubescent birch only Ca and Mg contents were decreased. In pubescent birch, fine cluster roots, the incidence of non-glandular trichomes, and stem lenticels were increased by growth waterlogging. However, silver birch did not show such acclimation to waterlogging. In conclusion, growth waterlogging caused more negative effects to both birch species than dormancy waterl...

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Cited by 369 publications

References 66 publications

The role of ABA and the transpiration stream in the regulation of the osmotic water permeability of leaf cells

The role of ABA and the transpiration stream in the regulation of the osmotic water permeability of leaf cells

Rapid Movements of Plants Organs Require Solute-Water Cotransporters or Contractile Proteins

Effect of waterlogging on boreal forest tree seedlings during dormancy and early growing season

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