Control Of Import And Export Of Photosynthate In Leaves
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Glucose inhibits the expression of triose phosphate/phosphate
the export of photosynthate out of chloroplasts and the import of raw materials needed for photosynthetic phos-phorylation in chloroplasts, TPT is closely related with photosynthetic carbon metabolism and plays an impor-tant role in regulating the distribution of photosynthate in wheat (Sun et al., 2004).
AN ABSTRACT OF THE THESIS OF Charles F. Forney for the degree
depend on the import of assimilates for growth, play a central role in determining assimilate distribution patterns within the plant (120). Sink-mediated control of assimilate distribution may be achieved through the sink's ability to accumulate assimilates from the phloem (41). The strawberry fruit is a strong sink for dry matter. Under
Why are Small Hass Fruit Small? - avocadosource
photosynthetic activity, photosynthate partitioning and yield. By comparison, horticulturalists have concentrated their efforts on ripening and senescence and post-harvest physiology. This dichotomy is largely a consequence of the type of plant product being generated and the economics involved. While it is clear that there exists a wealth
The sucrose-cleaving enzymes of plants are crucial for
source leaves is the synthesis of energy-rich molecules for the transport of carbon, whereas heterotrophic sink organs, such as developing fruits, seeds, roots and tubers are dependent on the import and utilization of these compounds. In most plant species, assimilated carbon is transported as sucrose, a disaccharide in
Source sink coupling in young barley plants and control of
Key words: Anoxia, barley, carbohydrate, leaves, phloem loading, temperature. Introduction Mass balance demands that a sustained carbon ﬂux out of a source leaf must equal the capacity of the sinks to utilize it. If utilization of assimilate by the sinks is altered, then this must be followed by a matching change in export from the source leaves.
Hormonal Regulation of Development III
3.5 Import of Assimilates into Expanded Leaves 11 3.6 Export of Assimilates When Leaves or Shoots Are Pretreated with Growth Substances 13 3.7 Time-Course Studies on Hormone-Induced Movement of 14C Assimilates 15 3.8 Effect of Hormone Concentration of Tran'slocation 16 3.9 Interaction of Different Hormones on Hormone-Directed Transport 16
Cytochrome c Deficiency Differentially Affects the In Vivo
Feb 26, 2021 ATP to the cytosol from photosynthetic cells, which can be used for the synthesis and export of sucrose in mature leaves or for growth in immature growing leaves [1,25]. As a further step, the use of genetically modiﬁed plants with altered components of the ATP-producing
REGULATION OF ABSCISIC ACID CONCENTRATION IN LEAVES OF FIELD
The concentration of ABA in leaves is determined by rates of its synthesis and metabolism, and by rates of import and export. In detached leaves the rise in [ABA] in response to water stress results largely from an increased rate of synthesis (Pierce & Raschke, 1981; Zeevaart, 1980; Murphy, 1984), while during rehydration
BOT 4503 3 Hours Photosynthate utilization, including phloem
Photosynthate utilization, including phloem transport Objectives 1. Summarize generally the fate of photosynthate. 2. Discuss, in general, the relative permeabilities of the inner and outer envelope of the chloroplast. 3. Write a brief essay on how the functioning of the phosphate translocator serves to maintain, at
Plant sink-source relationships and carbon isotopic labeling
photosynthesizing tissue and organ with export of carbon skeletons. Source organs are the photosynthetically active portions such as mature leaves. The sinks are the sites where assimilates are stored or used, or the ones requiring import of carbon (Long, 2005). Sink regions that draw
Integration of photosynthetic acclimation to CO2 at the whole
phosphate export from the chloroplast in a strict counter-exchange for Pi import into the chloroplast. This exchange Rubisco and leaf N concentration. A reductio~ in active rubisco (determined by either biochemical assay or leaf gas exchange) is one of the most commonly described acclimation responses to prolonged exposure to
EFFECTS OF DROUGHT STRESS ON SEED SINK STRENGTH AND LEAF
available for export to the sink organs (Kim et al., 2000). Drought can also affect carbohydrate metabolism in plant reproductive organs (Liu et al., 2004). For example, Setter et al. (2001) found higher or at least similar levels of sucrose in maize ovaries between drought-stressed and well-watered controls. These results imply that, in
Plasmodesmata signaling: many roles, sophisticated statutes
deliver photosynthate to developing tissues. Viruses expose the dynamic nature of plasmodesmata, however, as they trigger a dramatic increase in PD SEL great enough to export their genomes, either as virions or pro-tein/nucleic acid complexes, between cells and ultimately into the phloem (reviewed in [3,4 ,5]). The speed of viral
Carbohydrate partitioning and photosynthesis in Arabidopsis
require import of photosynthate, primarily in the form of sucrose, to maintain growth and metabolism. Examples would include roots, fruits, and young expanding leaves. Sources are leaves that have made the transition from importing to exporting photosynthate, and source strength is a measure of the capacity of leaves to assimilate carbon and export
Temporal Dynamics of Carbon Partitioning and
reduced compared with control plants at 3 h but was fairly similar to control plants at the end of the chase period. Mean total loss of 14C-labeled products to the rhizosphere in these plants was 0.6% of cumulative leaf export at 7.5 h. Control and defoliated plants differed significantly (P 140.05) in the measured val-
An Investigation into the Rate and Control of Assimilate
removal of photosynthate is more important in controlling export than the photosynthate build-up in the leaf itself. The non-destructive technique enabled comparisons to be made between export curves for individual plants. It was found that in experiments replicated in time, the same relationship
Research Commons at the University of Waikato Copyright Statement
the trunk of a non-girdled control vine (vine C4). Both transducers showed the same pattern of pressure with the (B) pressure transducer often with slightly higher pressure than the (A) pressure transducer. 29 Figure 2.11: Mean daily pressure (kPa) measured from two xylem pressure transducer in the trunk of control vine five (C5). The red circles
Physiological observations of maize (Zea mays L.) genotypes
(leaves) to export assimilate or the sink (fruit, root, stalk, and/or tiller) to import assimilate has been observed to change photosynthesis in many species (Kriedemann et al., 1976). The ratio of source to sink strength appears to exert control on the realized rate of photosynthesis.
Chemical Growth Retardant Effects on Easter Lilies
Ten plants each received the following treatments: 1) control; 2 -3) one or two sprays of 50 mg al.-liter-1 ancymidol; 4-9) one or two sprays of 5, 10, or 15 mg al.-liter-1 XE-1019; and 10) one spray of 20 mg al.-liter-1 XE -1019. The first applications were made on 22 January 1988; plant shoots averaged (t SD) 8.0 t 0.8 cm long, at this time
Plant performance: a physiological and genetic analysis using
active primarily in mature leaf mesophyll cells (the source), and photosynthate is transported via phloem, primarily as sucrose, to developing organs such as tubers, roots, flowers, fruits, or seeds (the sinks) which are characterized by a net import of sugars.
THE EFFECTS OF LIGHT ON BULBING IN ONIONS D.S. Bertaud ABSTRACT
Leaves that are no longer growing export carbohydrates through the stem to supply the youngest leaves (Mann, 1983), while in very young leaves, or scale leaves with no photosynthesising lamina, all carbohydrates are imported through the stem from older, photosynthesising leaves (Fig. 3). mature foliage leaf 1 'lamina 1 'sheath' J I
A rapid-equilibrium model for the control of the Calvin
facilitating the export of photosynthate and the import of orthophosphate required to sustain photosynthesis at a steady-state rate [6, 10 - 131. The opposite view has also been Correspondence to G. Pettersson, Avdelningen for Biokemi, Kemicentrum, Lunds Universitet, Box 124, S-22100 Lund, Sweden Abbreviations.
The Effects of Drought Stress on Assimilate Availability and
form of photosynthate for long-distance transport to sink organs, its concentration in leaves represents the current availability of assimilate for reproductive development (Westgate and Thomson 1989). Any effect of drought on synthesis, partitioning, export and utilization of sucrose would modify availability of the assimilate at source
Control of Import and Export of Photosynthate in Leaves
Control of Import and Export of Photosynthate in Leaves M. R. THORPE and ALEXANDER LANG Physics and Engineering Laboratory, DSIR, Private Bag, Lower Hutt, New Zealand Received 14 September 1982 ARSTR ATT The flow of photosynthetic assimilate in leaves was traced using radioactive C02. In younger leaves
On the Inside
import have revealed that targeting and import is speciﬁc for each organ-elle. However, over 100 proteins have now been reported to be dual targeted to mitochondria and plastids in a variety of plants. In addition to dual targeting to mitochondriaandplastids,dual targeting of proteins to mitochondria and peroxi-somes has also been reported
Dissection of Phloem Transport in Cucurbitaceae by
system according to net carbon import or export into two parts: the autotrophic photosynthate- producing source (e.g. mature leaves), and heterotrophic sink (e.g. developing leaves, roots, fruits, shoots) (Marson and Phillis, 1936; Sonnewald and Willmitzer, 1992).
BIOCHEMICAL AND PHYSIOLOGICAL ASPECTS OF LEAF DEVELOPMENT IN
photosynthate from older leaves. Towards the end of leaf expansion both glucose and fructose levels decline, although the sucrose content is still increasing. This possibly reflects the termination of the import of photosynthate by the leaf and the onset of an 300 400 200 1 100 Time (days) Fig. 4 10 Time (days) Fig. 5 Fig. 4.