Separating the contribution of the upper and lower mesophyll to photosynthesis in Zea mays L. leaves

Long, Stephen P.; Farage, P. K.; Bolhàr‐Nordenkampf, H. R.; Rohrhofer, U.

doi:10.1007/bf00392809

Cited by 37 publications

(58 citation statements)

References 12 publications

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“…3, C and D). Long et al (1989) demonstrated that there is a physical CO 2 diffusion barrier between adaxial and abaxial sides of C4 isobilateral leaves; therefore, the adaxial and abaxial sides of C4 isobilateral leaves can be viewed as separate compartments in terms of CO 2 diffusion and assimilation. The two separate compartment system is useful not only in the optimization of whole-leaf photosynthesis, but also allows the separation in the signaling of stress and in the effects of stress factors (Long et al, 1989; Soares- …”

Section: Discussion Systemic Regulation Of Leaf Morphology and Anatomymentioning

confidence: 99%

Systemic Regulation of Leaf Anatomical Structure, Photosynthetic Performance, and High-Light Tolerance in Sorghum

et al. 2011

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Leaf anatomy of C3 plants is mainly regulated by a systemic irradiance signal. Since the anatomical features of C4 plants are different from that of C3 plants, we investigated whether the systemic irradiance signal regulates leaf anatomical structure and photosynthetic performance in sorghum (Sorghum bicolor), a C4 plant. Compared with growth under ambient conditions (A), no significant changes in anatomical structure were observed in newly developed leaves by shading young leaves alone (YS). Shading mature leaves (MS) or whole plants (S), on the other hand, caused shade-leaf anatomy in newly developed leaves. By contrast, chloroplast ultrastructure in developing leaves depended only on their local light conditions. Functionally, shading young leaves alone had little effect on their net photosynthetic capacity and stomatal conductance, but shading mature leaves or whole plants significantly decreased these two parameters in newly developed leaves. Specifically, the net photosynthetic rate in newly developed leaves exhibited a positive linear correlation with that of mature leaves, as did stomatal conductance. In MS and S treatments, newly developed leaves exhibited severe photoinhibition under high light. By contrast, newly developed leaves in A and YS treatments were more resistant to high light relative to those in MS-and S-treated seedlings. We suggest that (1) leaf anatomical structure, photosynthetic capacity, and high-light tolerance in newly developed sorghum leaves were regulated by a systemic irradiance signal from mature leaves; and (2) chloroplast ultrastructure only weakly influenced the development of photosynthetic capacity and high-light tolerance. The potential significance of the regulation by a systemic irradiance signal is discussed.

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Section: Discussion Systemic Regulation Of Leaf Morphology and Anatomymentioning

confidence: 99%

Systemic Regulation of Leaf Anatomical Structure, Photosynthetic Performance, and High-Light Tolerance in Sorghum

et al. 2011

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“…The measurements here suggest this vein network acts as an effective lateral diffusion barrier. In addition, measurements by Long et al (1989) showed very limited transverse gas diffusion across maize leaves because of the limited connectivity between upper and lower surface airspaces, which would further restrict any lateral diffusion. However, we have previously found substantial lateral diffusion in another nongrass monocot species, C. communis (Morison et al, 2005), which suggests that a range of other monocots should be examined before a generalization is made.…”

Section: Lateral Co 2 Diffusion Is Low In Maizementioning

confidence: 99%

Lateral CO2 Diffusion inside Dicotyledonous Leaves Can Be Substantial: Quantification in Different Light Intensities

2007

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Substantial lateral CO 2 diffusion rates into leaf areas where stomata were blocked by grease patches were quantified by gas exchange and chlorophyll a fluorescence imaging in different species across the full range of photosynthetic photon flux densities (PPFD). The lateral CO 2 flux rate over short distances was substantial and very similar in five dicotyledonous species with different vascular anatomies (two species with bundle sheath extensions, sunflower [Helianthus annuus] and dwarf bean [Phaseolus vulgaris]; and three species without bundle sheath extensions, faba bean [Vicia faba], petunia [Petunia hybrida], and tobacco [Nicotiana tabacum]). Only in the monocot maize (Zea mays) was there little or no evident lateral CO 2 flux. Lateral diffusion rates were low when PPFD ,300 mmol m 22 s 21 but approached saturation in moderate PPFD (300 mmol m 22 s 21 ) when lateral CO 2 diffusion represented 15% to 24% of the normal CO 2 assimilation rate. Smaller patches and higher ambient CO 2 concentration increased lateral CO 2 diffusion rates. Calculations with a two-dimensional diffusion model supported these observations that lateral CO 2 diffusion over short distances inside dicotyledonous leaves can be important to photosynthesis. The results emphasize that supply of CO 2 from nearby stomata usually dominates assimilation, but that lateral supply over distances up to approximately 1 mm can be important if stomata are blocked, particularly when assimilation rate is low.

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“…A more direct way to assess the restriction to diffusion across the leaf is to follow an inert gas such as helium or N,O. This has yielded values of intercellular resistance across the leaf from 3 m2 s-' mol-' for Xanthium (Farquhar and Raschke, 1978;Mott and OLeary, 1984) up to 59 m2 s-' mol-' for Zea mays (Long et al, 1989). However, it is possible to determine this only with amphistomatous leaves, and since intercellular resistance to CO, diffusion involves lateral as well as vertical movement, these resistances are probably overestimates.…”

Section: Vertical Resistancementioning

confidence: 99%

Carbon Dioxide Diffusion inside Leaves

Evans¹,

Caemmerer²

1996

Plant Physiol.

375

301

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Leaves are beautifully specialized organs that enable plants to intercept light necessary for photosynthesis. The light is dispersed among a large array of chloroplasts that are in close proximity to air and yet not too far from vascular tissue, which supplies water and exports sugars and other metabolites. To control water loss from the leaf, gas exchange occurs through pores in the leaf surface, stomata, which are able to rapidly change their aperture. Once inside the leaf, CO, has to diffuse from the intercellular air spaces to the sites of carboxylation in the chloroplast (for C, species) (Fig. 1) or the cytosol (for C, species). These internal diffusion paths are the topic of this article.There are several reasons why internal diffusion is of interest. First, Rubisco has a poor affinity for CO, and operates at only a fraction of its catalytic capacity in C, leaves. The CO, gradient within the leaf thus affects the efficiency of Rubisco and the overall nitrogen use efficiency of the leaf. Second, prediction of photosynthetic rates of leaves from their biochemical properties requires a good estimate of the partial pressure of CO, at the sites of carboxylation, pc. Third, internal resistance to CO, diffusion results in a lower pc and reduces carbon gain relative to water loss during photosynthesis (water-use efficiency). Considerable effort is being invested selecting and identifying plants with improved water-use efficiency using the surrogate measure of carbon isotope discrimination, A, of plant dry matter (Ehleringer et al., 1993). The ratio of intercellular to ambient CO, partial pressure, pi/p,, and A are both linearly related to water-use efficiency if pc/pi is constant. To date, we have little knowledge of genetic variation in p c / p i .Until recently, it was not possible to directly measure the gradient in CO, partial pressure to the sites of carboxylation. The gradient could be inferred from a theoretical analysis of the diffusion pathway, but because several steps have unknown permeability constants, the values are uncertain. Opinion has oscillated from the existence of large to small gradients over the last 30 years. There are now two techniques that enable the gradient to be measured in C, leaves. After describing these techniques, we will consider diffusion through intercellular air spaces and diffusion across cell walls and liquid phase to sites of carboxylation. Finally, we will examine CO, diffusion into mesophyll cells and across the bundle sheath in C, leaves.* Corresponding author; e-mail evans8rsbs-centra1.anu.edu.au; fax 61-(0)6-249-4919. 339 TECHNIQUES FOR MEASURING CO, TRANSFER CON D UCTANC EConventional gas-exchange techniques measure fluxes of water and CO, into and out of a leaf. The gradient in partial pressure of CO, from ambient air to the substomatal cavities (usually referred to as p,) is derived using Ficks law of diffusion, which states that the gradient in partial pressure is equal to the flux divided by the conductance, i.e. pa -pi = A/g, where A is the rate of CO, assimilat...

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Separating the contribution of the upper and lower mesophyll to photosynthesis in Zea mays L. leaves

Cited by 37 publications

References 12 publications

Systemic Regulation of Leaf Anatomical Structure, Photosynthetic Performance, and High-Light Tolerance in Sorghum

Systemic Regulation of Leaf Anatomical Structure, Photosynthetic Performance, and High-Light Tolerance in Sorghum

Lateral CO2 Diffusion inside Dicotyledonous Leaves Can Be Substantial: Quantification in Different Light Intensities

Carbon Dioxide Diffusion inside Leaves

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