Measurement of a growth‐induced water potential gradient in tall fescue leaves

Martre, Pierre; Bogeat‐Triboulot, Marie‐Béatrice; Durand, J. L.

doi:10.1046/j.1469-8137.1999.00405.x

Cited by 31 publications

(29 citation statements)

References 35 publications

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“…In tall fescue leaves elongating in the dark under similar conditions and at the same rate, Martre et al (1999) found a ∆Ψ of about 0.3 MPa throughout the elongation zone. Combining this value with those for d water (Fig.…”

Section: Radial Hydraulic Conductivity and Water Deposition Rate Alonmentioning

confidence: 87%

“…There is evidence from the literature that the leaf elongation rate might decline within seconds in response to atmospheric or edaphic water deficits (Frensch, 1997). Cells in the growth zone have significantly lower water potential values than expanded cells of the maturation zone (Matsuda & Riazi, 1981 ;Michelena & Boyer, 1982 ;Barlow, 1986 ;Fricke & Flowers, 1998 ;Martre et al, 1999). A water potential difference between the water source (xylem) and sink (expanding mesophyll cells) is a prerequisite for growth.…”

Section: mentioning

confidence: 99%

“…0.4 Mpa. This would result in a xylem water potential close to the water potential of the elongating cells (Martre et al, 1999), which would reduce the water flux from the xylem lumen to the growing tissue. However, the rate of transpiration in the growing leaf of tall fescue would certainly be much less than that in the mature leaf, as the growing leaf is still partly rolled, and shaded by the older leaf.…”

Section: Axial Hydraulic Conductivitymentioning

confidence: 99%

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Changes in axial hydraulic conductivity along elongating leaf blades in relation to xylem maturation in tall fescue

2000

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Xylem maturation in elongating leaf blades of tall fescue (Festuca arundinacea) was studied using staining and microcasting. Three distinctive regions were identified in the blade : (1) a basal region, in which elongation was occurring and protoxylem (PX) vessels were functioning throughout ; (2) a maturation region, in which elongation had stopped and narrow (NMX) and large (LMX) metaxylem vessels were beginning to function ; (3) a distal, mature region in which most of the longitudinal water movements occurred in the LMX. The axial hydraulic conductivity (K h ) was measured in leaf sections from all these regions and compared with the theoretical axial hydraulic conductivity (K t ) computed from the diameter of individual inner vessels. K t was proportional to K h throughout the leaf, but K t was about three times K h . The changes in K h and K t along the leaf reflected the different stages of xylem maturation. In the basal 60 mm region, K h was about 0.30p0.07 mmol s −" mm MPa −" . Beyond that region, K h rapidly increased with metaxylem element maturation to a maximum value of 5.0p0.3 mmol s −" mm MPa −" , 105 mm from the leaf base. It then decreased to 3.5p0.2 mmol s −" mm MPa −" near the leaf tip. The basal expanding region was observed to restrict longitudinal water movement. There was a close relationship between the water deposition rate in the elongation zone and the sum of the perimeters of PX vessels. The implications of this longitudinal vasculature on the partitioning of water between growth and transpiration is discussed.

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Section: Radial Hydraulic Conductivity and Water Deposition Rate Alonmentioning

confidence: 87%

Section: mentioning

confidence: 99%

Section: Axial Hydraulic Conductivitymentioning

confidence: 99%

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Changes in axial hydraulic conductivity along elongating leaf blades in relation to xylem maturation in tall fescue

2000

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“…In monocotyledon leaves, the water status of the growing zone and of the xylem markedly differs from that of mature tissues (Martre et al, 1999). Indeed, mature tissues are located downstream of the growing zone, with a hydraulic connection that is not perfect because minor veins are still at a protoxylem stage (Martre et al, 2000).…”

Section: A Transcriptome Analysis Suggests Possible Contributions Of mentioning

confidence: 99%

A Hydraulic Model Is Compatible with Rapid Changes in Leaf Elongation under Fluctuating Evaporative Demand and Soil Water Status

et al. 2014

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Plants are constantly facing rapid changes in evaporative demand and soil water content, which affect their water status and growth. In apparent contradiction to a hydraulic hypothesis, leaf elongation rate (LER) declined in the morning and recovered upon soil rehydration considerably quicker than transpiration rate and leaf water potential (typical half-times of 30 min versus 1–2 h). The morning decline of LER began at very low light and transpiration and closely followed the stomatal opening of leaves receiving direct light, which represent a small fraction of leaf area. A simulation model in maize (Zea mays) suggests that these findings are still compatible with a hydraulic hypothesis. The small water flux linked to stomatal aperture would be sufficient to decrease water potentials of the xylem and growing tissues, thereby causing a rapid decline of simulated LER, while the simulated water potential of mature tissues declines more slowly due to a high hydraulic capacitance. The model also captured growth patterns in the evening or upon soil rehydration. Changes in plant hydraulic conductance partly counteracted those of transpiration. Root hydraulic conductivity increased continuously in the morning, consistent with the transcript abundance of Zea maize Plasma Membrane Intrinsic Protein aquaporins. Transgenic lines underproducing abscisic acid, with lower hydraulic conductivity and higher stomatal conductance, had a LER declining more rapidly than wild-type plants. Whole-genome transcriptome and phosphoproteome analyses suggested that the hydraulic processes proposed here might be associated with other rapidly occurring mechanisms. Overall, the mechanisms and model presented here may be an essential component of drought tolerance in naturally fluctuating evaporative demand and soil moisture.

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“…Osmolality and turgor pressure change little along the elongation zone of cereal leaves (Fricke et al, 1997;Fricke & Flowers, 1998;Martre et al, 1999;Fricke, 2002a) and roots (Pritchard, 1994). The implication of a constant turgor pressure in expanding cells might be that cells instantly deposit solutes to maintain osmolality as the osmotic force driving water uptake while they expand and cell contents become diluted (Fricke, 2002a).…”

Section: Solutesmentioning

confidence: 99%