Pico Gauges for Minimally Invasive Intracellular Hydrostatic Pressure Measurements

Knoblauch, Jan; Mullendore, Daniel L.; Jensen, Kaare H.; Knoblauch, Michael

doi:10.1104/pp.114.245746

Cited by 32 publications

(23 citation statements)

References 27 publications

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“…The measurement of water potential in plant leaves (Scholander et al, 1965 ) cannot reflect the rapid changes in water contents within tens of seconds in individual xylem vessel where water is refilled. But, a cell pressure probe (Wei et al, 1999 ; Knoblauch et al, 2014 ) can be employed to measure rapid change in xylem pressure when water refilling stops near perforation plates and water is refilled in a radial direction from adjacent cells and vessels. It requires a remote manipulation of the pressure probe in a delicate manner with submicron accuracy to simultaneously observe water-refilling phenomena by using X-ray microscope.…”

Section: Discussionmentioning

confidence: 99%

Vulnerability of Protoxylem and Metaxylem Vessels to Embolisms and Radial Refilling in a Vascular Bundle of Maize Leaves

2016

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Regulation of water flow in an interconnected xylem vessel network enables plants to survive despite challenging environment changes that can cause xylem embolism. In this study, vulnerability to embolisms of xylem vessels and their water-refilling patterns in vascular bundles of maize leaves were experimentally investigated by employing synchrotron X-ray micro-imaging technique. A vascular bundle in maize consisted of a protoxylem vessel with helical thickenings between two metaxylem vessels with single perforation plates and nonuniformly distributed pits. When embolism was artificially induced in excised maize leaves by exposing them to air, protoxylem vessels became less vulnerable to dehydration compared to metaxylem vessels. After supplying water into the embolized vascular bundles, when water-refilling process stopped at the perforation plates in metaxylem vessels, discontinuous radial water influx occurred surprisingly in the adjacent protoxylem vessels. Alternating water refilling pattern in protoxylem and metaxylem vessels exhibited probable correlation between the incidence location and time of water refilling and the structural properties of xylem vessels. These results imply that the maintenance of water transport and modulation of water refilling are affected by hydrodynamic roles of perforation plates and radial connectivity in a xylem vascular bundle network.

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Section: Discussionmentioning

confidence: 99%

Vulnerability of Protoxylem and Metaxylem Vessels to Embolisms and Radial Refilling in a Vascular Bundle of Maize Leaves

2016

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“…The development of new methods for laboratory experiments such as position emission tomography(PET, Hubeau and Steppe 2015), picogauge tissue pressure measurements (Knoblauch et al 2014) and magnetic resonance imaging (MRI, Windt et al 2006) has allowed progress in studying phloem transport in non-woody plants. However, phloem transport, and the interplay between its structure and function still remains poorly understood (Savage et al 2016) because of the challenges in studying phloem in woody plants and in any plants under field conditions.…”

Section: Introductionmentioning

confidence: 99%

Drought impacts on tree phloem: from cell-level responses to ecological significance

et al. 2019

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On-going climate change is increasing the risk of drought stress across large areas worldwide. Such drought events decrease ecosystem productivity and have been increasingly linked to tree mortality. Understanding how trees respond to water shortage is key to predicting the future of ecosystem functions. Phloem is at the core of the tree functions, moving resources such as non-structural carbohydrates, nutrients, and defence and information molecules across the whole plant. Phloem function and ability to transport resources is tightly controlled by the balance of carbon and water fluxes within the tree. As such, drought is expected to impact phloem function by decreasing the amount of available water and new photoassimilates. Yet, the effect of drought on the phloem has received surprisingly little attention in the last decades. Here we review existing knowledge on drought impacts on phloem transport from loading and unloading processes at cellular level to possible effects on long-distance transport and consequences to ecosystems via ecophysiological feedbacks. We also point to new research frontiers that need to be explored to improve our understanding of phloem function under drought. In particular, we show how phloem transport is affected differently by increasing drought intensity, from no response to a slowdown, and explore how severe drought might actually disrupt the phloem transport enough to threaten tree survival. Because transport of resources affects other organisms interacting with the tree, we also review the ecological consequences of phloem response to drought and especially predatory, mutualistic and competitive relations. Finally, as phloem is the main path for carbon from sources to sink, we show how drought can affect biogeochemical cycles through changes in phloem transport. Overall, existing knowledge is consistent with the hypotheses that phloem response to drought matters for understanding tree and ecosystem function. However, future research on a large range of species and ecosystems is urgently needed to gain a comprehensive understanding of the question.

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“…Specific structural phloem proteins (P-proteins) occurring as filaments or persistent crystalline structures in the majority of sieve elements of angiosperms ( Fig. 11) do not seem to have a large influence on assimilate transport in intact sieve tubes (Froelich et al, 2011;Knoblauch et al, 2014). Wounding of the phloem by mechanical impacts and pathogen attacks is, however, thought to lead to the accumulation of such proteins on and in sieve pores.…”

Section: A Phloem Anatomymentioning

confidence: 99%

“…In trees, where the high number of sieve elements in the bark makes them more accessible, a needle with a narrow tip produced by pulling a glass capillary tube has been used (Hammel, 1968;Lee, 1981;Sovonick-Dunford et al, 1981). This technique was also recently used to measure pressure inside translocating sieve elements in the herbaceous bean plant Vicia faba (Knoblauch et al, 2014). The measured pressures lie in the range of p ¼ 0.6-1.4 MPa for trees, while it can reach up to p ¼ 2.4 MPa in herbaceous plants (Wright and Fisher, 1980;Lee, 1981;Sovonick-Dunford et al, 1981;Fisher and Cash-Clark, 2000).…”

Section: Phloem Cell Pressurementioning

confidence: 99%

“…Disturbance of the sieve element (e.g., mechanically or by cooling) can cause local stopping of the flow, for instance, by occlusion of the sieve tube by forisomes (a class of contractile proteins) or by clogging of the sieve plates [Fig. 1(d)] (Lang and Minchin, 1986;Knoblauch et al, 2014). Suspension of translocation is widespread throughout the plant kingdom and may be an important control mechanism.…”

Section: Introductionmentioning

confidence: 99%

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Sap flow and sugar transport in plants

et al. 2016

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Green plants are Earth's primary solar energy collectors. They harvest the energy of the Sun by converting light energy into chemical energy stored in the bonds of sugar molecules. A multitude of carefully orchestrated transport processes are needed to move water and minerals from the soil to sites of photosynthesis and to distribute energy-rich sugars throughout the plant body to support metabolism and growth. The long-distance transport happens in the plants' vascular system, where water and solutes are moved along the entire length of the plant. In this review, the current understanding of the mechanism and the quantitative description of these flows are discussed, connecting theory and experiments as far as possible. The article begins with an overview of low-Reynolds-number transport processes, followed by an introduction to the anatomy and physiology of vascular transport in the phloem and xylem. Next, sugar transport in the phloem is explored with attention given to experimental results as well as the fluid mechanics of osmotically driven flows. Then water transport in the xylem is discussed with a focus on embolism dynamics, conduit optimization, and couplings between water and sugar transport. Finally, remarks are given on some of the open questions of this research field.

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Pico Gauges for Minimally Invasive Intracellular Hydrostatic Pressure Measurements

Cited by 32 publications

References 27 publications

Vulnerability of Protoxylem and Metaxylem Vessels to Embolisms and Radial Refilling in a Vascular Bundle of Maize Leaves

Vulnerability of Protoxylem and Metaxylem Vessels to Embolisms and Radial Refilling in a Vascular Bundle of Maize Leaves

Drought impacts on tree phloem: from cell-level responses to ecological significance

Sap flow and sugar transport in plants

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