Specialized cellular arrangements in legume leaves in relation to assimilate transport and compartmentation: comparison of the paraveinal mesophyll

Planta ◽  
1983 ◽  
Vol 159 (5) ◽  
pp. 415-422 ◽  
Author(s):  
Vincent R. Franceschi ◽  
Robert T. Giaquinta
Keyword(s):  
Assimilate Transport ◽  
Paraveinal Mesophyll

The paraveinal mesophyll: a specialized path for intermediary transfer of assimilates in legume leaves

2000 ◽  
Vol 27 (9) ◽  
pp. 757 ◽  
Author(s):  
Alexis J. Lansing ◽  
Vincent R. Franceschi
Keyword(s):  
Vascular System ◽  
Phloem Loading ◽  
Assimilate Transport ◽  
Vascular Bundles ◽  
Transport Pathway ◽  
Mesophyll Cells ◽  
Diffusion Limitations ◽  
Unit Leaf ◽  
Paraveinal Mesophyll ◽  
Leaf Surface Area

This paper originates from a presentation at the International Conference on Assimilate Transport and Partitioning, Newcastle, NSW, August 1999 The distance between sites of synthesis of assimilates and the site of phloem loading can be large, and specialized leaf cell layers such as the paraveinal mesophyll (PVM) might act to enhance the efficiency of transport. A number of techniques were used to analyse PVM of legume leaves with respect to a hypothesized function in transfer of assimilates between tissues. Of 39 legume species examined, PVM was found in 22. Leaves of all PVM-containing species had multiple palisade parenchyma layers, while non-PVM species generally had only one distinct palisade layer. Morphometric analysis identified a significant correlation between PVM presence and greater numbers of palisade cells per unit leaf surface area. Comparison of photosynthetic rates of four PVM and four non-PVM species showed the PVM species had higher rates on a leaf area basis than all but one of the non-PVM species. Microautoradiography of 14CO2 pulse–chase studies in soybean demonstrated PVM is an intermediary tissue in transfer of assimilates to vascular bundles. In addition, PVM cells but not mesophyll cells, were enriched in a sucrose binding protein previously found to be associated with sucrose-transporting tissues. The structural, positional and transport data support the hypothesis that the PVM acts as a transport pathway between the vascular system and photoassimilatory cells of the leaf, and has probably evolved to overcome diffusion limitations imposed by multiple palisade layers.

744 PB 076 IDENTIFICATION OF BOTH ACID AND NEUTRAL INVERTASE ACTIVITY IN DEVELOPING STRAWBERRY FRUIT

HortScience ◽  
1994 ◽  
Vol 29 (5) ◽  
pp. 539f-539
Author(s):  
Kirk W. Pomper ◽  
Patrick J. Breen
Keyword(s):  
Extraction Procedure ◽  
Invertase Activity ◽  
Assimilate Transport ◽  
Strawberry Fruit ◽  
Fruit Extracts ◽  
Neutral Invertase ◽  
Optimum Ph ◽  
Cold Acetone ◽  
Ripe Stage ◽  
Sugar Levels

Invertase (INV) may influence sugar levels and assimilate transport in strawberry fruit. Several groups, including our own, have only detected acid INV (optimum pH 4.6) in strawberry fruit, however, recently Hubbard et al. (Physiol. Plant. 82:191-196, 1991) reported the presence of a neutral INV (pH 7.5). Since dissimilar isolation protocols may have contributed to the different findings, we re-examined our work with developing `Brighton' strawberry using the extraction procedure of Hubbard et al. Neutral INV activity per gFW (pH 7.5-8.0) increased many fold as fruit developed from green to the red ripe stage. Acid INV activity decreased markedly from green-white to the red stage. In addition, when fruit extracts were precipitated with cold acetone, a pellet contained 60% of the acid INV activity, and a surface coagulation of protein contained 60% of the neutral INV activity. This allowed easy separation of these two enzymes. Extraction methodologies affect isolation of neutral INV activity from strawberry fruit.

Physiological Basis for the Different Phloem Mobilities of Chlorsulfuron and Clopyralid

Weed Science ◽  
1990 ◽  
Vol 38 (1) ◽  
pp. 1-9 ◽  
Author(s):  
Malcolm D. Devine ◽  
Hank D. Bestman ◽  
William H. Vanden Born
Keyword(s):  
Leaf Tissue ◽  
Phloem Transport ◽  
Assimilate Transport ◽  
Herbicide Application ◽  
Irreversible Binding ◽  
Sensitive Species ◽  
Physiological Basis ◽  
Treated Leaf ◽  
Phloem Translocation ◽  
Leaf Disks

Foliar-applied clopyralid was translocated much more readily than chlorsulfuron in the phloem of Tartary buckwheat plants. This result was not due to greater penetration of clopyralid into the treated leaf or to greater retention of chlorsulfuron in the cuticle. Experiments with excised leaf disks indicated that chlorsulfuron was taken up more readily by the leaf tissue and accumulated in the tissue to a higher concentration than clopyralid. Both herbicides effluxed readily from the tissue after transfer to herbicide-free medium, indicating that the accumulation was not due to irreversible binding within the tissue. Chlorsulfuron (2.8 nmol) applied with14C-sucrose reduced14C export from the treated leaf. Chlorsulfuron also reduced export of14C following exposure of the treated leaf to14CO2at 6, 12, or 24 h after herbicide application. This effect of chlorsulfuron could be partially reversed by pretreating the plants with a combination of 1 mM valine, leucine, and isoleucine. In similar experiments clopyralid had no effect on assimilate transport. It is concluded that phloem translocation of chlorsulfuron in sensitive species is limited by a rapid, indirect effect on phloem transport that reduces both its own translocation and that of assimilate.

The functional status of paraveinal mesophyll vacuoles changes in response to altered metabolic conditions in soybean leaves

2005 ◽  
Vol 32 (4) ◽  
pp. 335 ◽  
Author(s):  
Kimberly A. Murphy ◽  
Rachel A. Kuhle ◽  
Andreas M. Fischer ◽  
Aldwin M. Anterola ◽  
Howard D. Grimes
Keyword(s):  
Functional Status ◽  
Storage Proteins ◽  
Vegetative Storage Proteins ◽  
Paraveinal Mesophyll ◽  
Lytic Function ◽  
Metabolic Conditions ◽  
Glycine Max L ◽  
Soybean Leaves ◽  
And Storage ◽  
Lytic Compartment

Antibodies raised against tonoplast intrinsic proteins (TIPs) were used to probe the functional status of the soybean [Glycine max (L.) Merr.] paraveinal mesophyll (PVM) vacuole during changes in nitrogen metabolism within the leaf. Young plants grown under standard conditions had PVM vacuoles characterised by the presence of γ-TIP, which is indicative of a lytic function. When plants were then subjected to shoot tip removal for a period of 15 d, forcing a sink-limited physiological condition, the γ-TIP marker diminished while the δ-TIP marker became present in the PVM vacuole, indicating the conversion of the PVM vacuole to a storage function. When the shoot tips were allowed to regrow, the γ-TIP marker again became dominant demonstrating the reversion of these PVM vacuoles back to a lytic compartment. The changes in TIP markers correlated with the accumulation of vegetative storage proteins and vegetative lipoxygenases, proteins implicated in nitrogen storage and assimilate partitioning. This research suggests that the PVM vacuole is able to undergo dynamic conversion between lytic and storage functions and further implicates this cell layer in assimilate storage and mobilisation in soybeans.

Uptake, partitioning and utilization of carbon and nitrogen in the phloem bleeding tree, Tasmanian blue gum (Eucalyptus globulus)

2000 ◽  
Vol 27 (9) ◽  
pp. 869
Author(s):  
John S. Pate ◽  
David J. Arthur
Keyword(s):  
Eucalyptus Globulus ◽  
Assimilate Transport ◽  
Concentration Gradients ◽  
Phloem Sap ◽  
Empirical Modelling ◽  
Carbon And Nitrogen ◽  
C And N ◽  
Four Levels ◽  
Gains And Losses ◽  
Growing Shoot

This paper originates from a presentation at the International Conference on Assimilate Transport and Partitioning, Newcastle, NSW, August 1999 An empirical modelling procedure was employed to follow uptake, transport and utilization of photo-assimilated carbon (C) and soil-derived nitrogen (N) over a 19-d period (November 1998) in 2-year-old plantation-grown trees of Eucalyptus globulus Labill. Models utilized data for gains and losses of C and N in dry matter (DM) of tree parts, CO2 exchanges and transpiration of foliage, respiratory losses of stems and roots, C:N weight ratios of xylem and phloem sap collected at different sites within the system, and phloem sap sugar concentration gradients along trunks and branches to indicate directions of assimilate flow. The model for C depicted the fate of exported fixed C from four levels of branches on the shoot system, cycling of 16% of the C supplied from shoot to root back to the shoot in xylem, major involvement of xylem-derived C in nourishment of rapidly growing branches, and a net daily respiratory output per tree equivalent to 39% of its net daytime photosynthetic gain in C by foliage. The model for N showed that upper growing shoot parts gained more N mobilized from lower branches than was being acquired from soil. It also indicated high rates of cycling of N through mature foliage, effective retention of xylem-derived N by growing branches and apices, and feedback of substantial amounts of phloem-exported N from lower branches into xylem moving further up the trunk. Transpiration loss per tree was equivalent to 272 mL g–1 DM accumulated. Data are discussed in relation to similarly executed C:N partitioning studies on herbaceous annual species.

Bark Banding of Pinus radiata with Morphactin (IT3456): Influence on Trunk Anatomy Assimilate Transport and Growth

1977 ◽  
Vol 39 (4) ◽  
pp. 280-284 ◽  
Author(s):  
ROBERT P. DOSS ◽  
PETER M. NEUMANN ◽  
RALPH A. BACKHAUS ◽  
ROY M. SACHS
Keyword(s):  
Pinus Radiata ◽  
Assimilate Transport
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