Skip Navigation


AOBPreview originally published online on August 7, 2003
This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Content Snapshot
Right arrow Content Select
Right arrow All Versions of this Article:
92/4/523    most recent
mcg159v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (13)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by WANG, Z.-P.
Right arrow Articles by LOPEZ, F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by WANG, Z.-P.
Right arrow Articles by LOPEZ, F.
Agricola
Right arrow Articles by WANG, Z.-P.
Right arrow Articles by LOPEZ, F.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Annals of Botany 92: 523-528, 2003
© 2003 Annals of Botany Company

An in vivo Experimental System to Study Sugar Phloem Unloading in Ripening Grape Berries During Water Deficiency Stress

ZHEN-PING WANG1,2, ALAIN DELOIRE*,1, ALAIN CARBONNEAU1, BRIGITTE FEDERSPIEL1 and FRANÇOIS LOPEZ1

1 AGRO Montpellier, UMR 1083 ‘Sciences pour l’Oenologie et la Viticulture’, 2 place P.Viala, F-34060 Montpellier Cedex 1, France and 2 Ningxia University of China, Yinchuan, 750021 Ningxia, China

* For correspondence. E-mail deloire{at}ensam.inra.fr

Received: 31 January 2003; Returned for revision: 28 April 2003; Accepted: 10 June 2003    Published electronically: 7 August 2003


   ABSTRACT
TOP
 ABSTRACT
INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSION
 LITERATURE CITED
 

An in vivo experimental system—called the ‘berry-cup’ technique—was developed to study sugar phloem unloading and the accumulation of sugar in ripening grape berries. The berry-cup system consists of a single peeled grape berry immersed in a buffer solution in a cup prepared from a polypropylene syringe. A small cross-incision (2 mm in length) is made on the stylar remnant of a berry during its ripening phase, the skin of the berry then being easily peeled off, exposing the dorsal vascular bundles without damaging either these or the pulp tissue of the berry. The sites of sugar phloem unloading are thus made directly accessible and may be regulated by the buffer solution. In addition, the unloaded photoassimilates are easily transported into the buffer solution in the berry-cup. With the berry-cup technique, it takes 60 min to purge the sugar already present in the apoplast, after which the amount of sugar in the buffer solution is a direct measure of the sugar unloading from the grape berry phloem. The optimum times for sampling were 20 or 30 min, depending on the type of experiment. Sugar phloem unloading was significantly inhibited by the inclusion of either 7·5 mM NaF or 2·5 mM PCMB in the buffer solution. This study indicates that sugar phloem unloading in ripening grape berries is via the apoplastic network and that the process requires the input of energy. The system was shown to be an appropriate experimental system with which to study sugar phloem unloading in ripening grape berries, and was applied successfully to the study of berry sugar unloaded from grapevines subjected to water stress. The results showed that water deficiency inhibits sugar unloading in grape berries.

Key words: Sugar phloem unloading, ‘berry-cup’ technique, ripening grape berry, inhibitors, water deficiency.


   INTRODUCTION
TOP
 ABSTRACT
 INTRODUCTION
MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSION
 LITERATURE CITED
 
In the last two decades, following an initial surge of interest in the mechanism of phloem loading in leaves, a number of scientists turned their attention to sink regions of the plant and to the study of the pathway and mechanisms of phloem unloading. It is now well accepted that the sink regions of plants exert considerable influence in determining the pattern of photoassimilate distribution in plants (Ho, 1988; Patrick, 1990, 1997). Phloem unloading has been defined as the series of transport steps that solutes make from the sieve element lumen to sites of utilization in the recipient sink cells (Oparka, 1990). It is necessary to investigate the mechanisms of phloem unloading so that the effect of environmental factors on sugar accumulation in sink organs can be determined.

Following long-distance transport in the phloem, the exit of photoassimilates from the sieve elements is the first step in a complex series of short-distance steps within the sink organs (Oparka, 1990). Some techniques have been described for the specific study of phloem unloading. For example, the ‘empty seed coat’ or ‘empty-ovule’ method was used for the study of phloem unloading in seed coats (Thorne and Rainbird, 1983; Wolswinkel and Ammerlaan, 1983; Gifford and Thorne, 1986). The ‘unloading trap technique’ was used for the study of phloem unloading in growing potato tubers (Oparka and Prior, 1987) and apples (Lü et al., 1999). These methods have the drawbacks of amputating the phloem and injuring the sink organ tissue, and make it difficult to find a suitable position to approach the phloem unloading point. The ‘tissue disk technique’ was used to study photoassimilate unloading, and the accumulation and metabolism of sugar in tomatoes (Damon et al., 1988), strawberries (Ofosu-Anim and Yamaki, 1994) and grape berries (Findlay et al., 1987). This method can also injure the phloem and surrounding tissue and does not produce reproducible results.

An isotopic tracer technique has also been used to study phloem unloading (Thorne and Rainbird, 1983; Wolswinkel and Ammerlaan, 1983; Xia, 1999). Not only can this method alter the growing environment of the plant, but the technique is cumbersome, costly and requires the availability of highly skilled personnel. Therefore, we considered it important to find a new technique to help quantify sugar phloem unloading in grape (Vitis vinifera L.) berries.

Grape berries exhibit a double sigmoid pattern of development, with two distinct phases of growth separated by a lag phase (Coombe, 1992; Robinson and Davies, 2000). The ripening phase in the maturation of grape berries occurs during the second growth period and results from the expansion, without multiplication, of pericarp cells (Ojeda et al., 2001). Veraison after the lag phase is defined as the beginning of berry ripening and sugar accumulation. This stage is characterized by berry softening and the accumulation of anthocyanins in red grape varieties (Coombe, 1992). Sugar accumulation occurs during the ripening phase and begins immediately after softening.

In this paper, a novel method is described which uses a berry-cup in an in vivo experimental system to study sugar phloem unloading in ripening grape berries. The method can also be used to study the effect of various internal and external factors on sugar accumulation in grape berries.


   MATERIALS AND METHODS
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
RESULTS AND DISCUSSION
 CONCLUSION
 LITERATURE CITED
 
Plant material and growth conditions
All experiments were performed on 12-year-old Syrah vines (Vitis vinifera L.), grafted on Fercal rootstocks, trained on lyre (the official name for a type of grapevine training system), planted in pots of 70 l in the Ecotron experimental system (AGRO-Montpellier, France). The rows of vines were arranged in a north–south orientation. The horticultural substratum was a mixture of Perlite and sand (9 : 1 by volume). Fertilization and irrigation were assured by a drip-irrigation system. Plant water status was controlled by the predawn leaf water potential ({Psi}b) (Scholander et al., 1965; Carbonneau, 1998). The {Psi}b of the control vines was 0 >= {Psi}b >= –0·2 MPa and –0·5 >= {Psi}b >= –0·6 MPa for the water-stressed vines.

Preparation of the berry-cup in vivo experimental system
The experiment was carried out between veraison and ripening. Well-developed primary stems with grape clusters were chosen from ten individual vines; one-third of the berries were cut away to facilitate the setting up of the berry-cup. The berry-cups were installed in the centre of the grape clusters and a berry close to the stem was chosen for the berry-cup. The cup parts of the berry-cup configuration were prepared by cutting 20 ml polypropylene syringes to a height of 2 cm from the exit spout of the syringe; the total capacity of the cup was 10 ml. The exit spout of the syringe was connected to a Teflon tube (TT in Fig. 1) fitted with a valve (V in Fig. 1) to permit emptying of the cup. The cup was filled with buffer by means of an injection pipe (IP in Fig. 1). The surface of the cup was covered with an aluminum-coated sponge material (ACSM in Fig. 1) to protect the berry-cup from light and to keep the temperature at 24–30 °C.



View larger version (38K):
[in this window]
[in a new window]
  		Fig. 1. Experimental arrangement of the ‘berry-cup’ system for the study of sugar phloem unloading. ACSM, Aluminium-coated sponge material; BF, buffer solution; C, cup; DVB, dorsal vascular bundle; FPS, fruiting primary stem; GC, grape cluster; IP, injection pipe; V, valve; PF, Parafilm; RBS, remaining berry skin; TT, Teflon tube.

 
A small cross-incision (2 mm in length) was made with a scalpel on the stylar remnant, which is the end link point of the dorsal vascular bundles. The incision was made so as not to damage the pulp tissue. The berry skin was then completely peeled away from the stylar remnant with tweezers and scissors. Different buffer solutions were evaluated in order to determine the buffer that most closely resembles the natural pH and ionic strength of the grape berry. The buffer finally selected consisted of 5 mM 2(N-morpholino) ethanesulfonic acid (MES), 2 mM CaCl2, 100 mM D-mannitol and 0·2 % (w/v) polyvinylpyrrolidone (PVP), pH 5·5, otherwise referred to as ‘standard MES buffer’. This buffer solution was added into a prepared cup, followed immediately by the peeled berry. The top of the berry-cup was then sealed with Parafilm (PF in Fig. 1). If necessary, the buffer solution could be topped up via the injection pipe (IP in Fig. 1). To change buffer solutions, the valve on the Teflon tube was opened and the entire contents drained into a test-tube. After closing the valve, fresh buffer was introduced via the injection pipe. Buffer solution could be replaced in 30 s maximum.

Determination of the experimental collecting time
To determine how quickly the buffer solution became saturated with sugar, 18 berry-cups were prepared and divided into six groups of three. The buffer solution of the three berry-cups in the first group was drained into test-tubes after 10 min, and after 20, 30, 40, 50 and 60 min for the second to sixth groups, respectively. The 18 samples were then frozen at –80 °C before analysis.

Determination of the efflux kinetics of the sugars in vivo
To determine the efflux kinetics of the sugar in a peeled berry in vivo, the buffer solution was replaced every 20 min with fresh buffer solution. Each drained buffer solution constituted one sample. For any given berry-cup, the maximum number of buffer changes was seven, amounting to a total of seven samples for each berry-cup within an experimental period of 140 min. As three berry-cups were prepared in this experiment, the total number of samples was 21. The samples (i.e. drained buffer solutions) were frozen at –80 °C before analysis. This experiment was repeated three times

Preparation and treatment of metabolic inhibitors
The respiratory metabolic inhibitor, sodium fluoride (NaF) was chosen because of its inhibitory effect on the inhibition of energy production which in turn inhibits sugar phloem unloading (Thorne, 1985; Xia, 1999). The NaF solution was prepared prior to each experiment by adding it to the MES buffer; a concentration of 7·5 mM NaF being used as previously described by Xia (1999). p-(chloromercurio) benzoic acid (PCMB), a modifier of cysteine groups, was also chosen, because of its inhibitory effects on sugar transportation, which in turn inhibits apoplastic phloem unloading. The PCMB solution was prepared prior to each experiment by incorporating it into to the MES buffer at a concentration of 2·5 mM. To determine the effect of the inhibitors on sugar phloem unloading, three groups of three berry-cups were used. In the first (control) group, the buffer solution was changed every 30 min over a period of 180 min. In the other two (treatment) groups, the berry-cups were treated in the same way as the controls for 30 min (i.e. 30 min immersion in standard MES buffer solution), followed by immersion for 3 x 30 min in buffer containing either 7·5 mM NaF or 2·5 mM PCMB. For the four succeeding immersions, the samples were treated in the same way as the control group. In both cases (control and treatment groups) sampling was carried out after an apoplastic draining period of 60 min and the samples were frozen at –80 °C before analysis. This experiment was repeated three times.

The variation in the percentage of sugar phloem unloading was calculated using the following expression:


where {Delta}S is the change in percentage of sugar phloem unloading; S0 is the quantity of sugar phloem unloaded during the first 30 min and Sn is the quantity of sugar phloem unloading after n buffer collections.

Sugar analysis
The collected samples were thawed at room temperature (20 °C), and adjusted to 10 ml with distilled water. A 50 µl aliquot was used to determine the concentrations of sucrose, D-glucose and D-fructose by an enzymatic kit method (Boehringer Mannheim, Darmstadt, Germany) using a spectrophotometer.

To follow the berry growth we weighed samples of 50 berries from the population (several repetitions). The quantity of sugar phloem unloading was expressed in terms of weight per gram of fresh berry. We cannot weigh the berries used for the ‘berry-cup’ so we measured their diameter and weighed berries from the population with a similar diameter (there is a correlation between berry diameter and fresh weight; R2 = 0·98).

Effect of water stress on the phloem sugar unloading
The berry-cup technique was used to compare berry sugar unloading in normally hydrated and water stressed grapevines. Grapevine water status was measured in terms of the predawn leaf water potential ({Psi}b) (Scholander et al., 1965; Carbonneau, 1998). During phase I and the early parts of phase II (until 54 d after anthesis, DAA), all the grapevines were irrigated normally ({Psi}b of the grapevines was {Psi}b –0·2 MPa). In late phase II (54 DAA, i.e. 5 d before veraison, DBV), the grapevines were divided into two groups, control grapevines and treated (water-stressed) grapevines, each group consisting of 11 plants. The experiments were carried out weekly during the maturation period of the berries during which the {Psi}b of the control grapevines was determined to be {Psi}b –0·2 MPa and that of the water-stressed grapevines was –0·5 >= {Psi}b >= –0·6 MPa. By way of an example, the results obtained for an experiment carried out 82 d after anthesis, i.e. 23 d after veraison (DAA) are presented. A kinetic study was carried out over a single day on the same berry-cup at four time intervals (0900 h, 1200 h, 1500 h and 1800 h). The buffer was replaced every 30 min, and with each buffer change, the berry-cups were immediately refilled with fresh buffer solution to prevent desiccation of the berry. The apoplastic sugar was purged with the buffer solution for 60 min before the first experiment at 0900 h. The 24 samples were then frozen at –80 °C before analysis.


   RESULTS AND DISCUSSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
CONCLUSION
 LITERATURE CITED
 
Experimental system to study sugar phloem unloading in ripening grape berries
To investigate sugar phloem unloading in grape berries reliably, it is essential to establish an experimental system that does not cause injury to either the phloem or the pulp. It is also important to reduce the distance between the phloem and the buffer solution (Thorne, 1985; Ho, 1988).

In mature berries, the skin can be removed readily, thus exposing the dorsal vascular bundles. The sites of sugar phloem unloading are therefore easily accessible by the buffer, which may modulate the flow of sugar in the phloem. Furthermore, the unloaded photoassimilates can easily be transported into the buffer solution in the berry-cup. The berry-cup design (Fig. 1) is such that the opera tions of collecting and changing the buffer solution are accomplished easily and quickly.

Determination of the experimental collecting time
The accumulation of sugar in the buffer solution increased over 50 min, after which the solution became saturated, as evidenced by the levelling off of the sugar concentration curve (Fig. 2). Thus, for reliable results, collection times of 20 or 30 min were chosen depending on the individual experiment.



View larger version (10K):
[in this window]
[in a new window]
  		Fig. 2. Buffer sugar content as a function of sampling time. The buffer solution of the berry-cup becomes saturated after 50 min. The results shown are the mean values (n = 3 replicate berry-cups) of sugar efflux (µg g–1 berry) from the peeled berry into the buffer solution.

 
Efflux kinetics of sugars from an in vivo grape berry
It has been shown that glucose and fructose were the major sugars in the phloem unloading solution. It has also been shown previously that the sugar unloaded from the phloem is accumulated in the vacuole via the apoplastic system (Gifford and Thorne, 1986; Dreier et al., 1998). In this study, two distinct phases were identified in the time course of the efflux: a rapid decline over the first 60 min, which in some runs, showed signs of stabilizing after 60 min (Fig. 3). The first phase (0–60 min) is characterized by apoplastic purging and the second phase (60–160 min) is characterized by equilibration of the sugar content between the apoplast and the buffer solution. The end of the apoplastic purge was also accompanied by a transient increase in sugar efflux. As the second portion of the graph (after the arrow) shown in Fig. 3 represents phloem unloading in relation to photosynthesis (sink–source relationship), the efflux kinetics were determined in subsequent experiments after an apoplastic purge of 60 min (three buffer changes, each after 20 min).



View larger version (21K):
[in this window]
[in a new window]
  		Fig. 3. Efflux of sucrose, glucose and fructose from a peeled berry over 160 min. For the first 60 min (arrow) the decline in sugar efflux corresponds to apoplastic purging. Thereafter, the sugar efflux represents the sugar phloem unloading of the grape berry. The results shown are the mean values (n = 3 replicate berry-cups) of sugar efflux (µg g–1 berry) from the peeled berry into the buffer solution.

 
Effect of NaF and PCMB on sugar unloading of the grape berry
Sodium fluoride (NaF) is a phosphatase inhibitor of respiratory electron transport. Incorporation of 7·5 mM NaF into the buffer solution significantly inhibits sugar phloem unloading in grape berries (Fig. 4). These results also show that NaF can act rapidly on phloem to inhibit the production of energy, and that it continues to exert this inhibitory effect for up to 60 min after it has been removed from the MES buffer solution. These findings support the observation that sugar phloem unloading is a process that requires energy in ripening grape berries (Thorne, 1985; Xia, 1999).



View larger version (17K):
[in this window]
[in a new window]
  		Fig. 4. Effect of NaF and PCMB on sugar unloading in grape berries. {Delta}S is the variation in percentage of sugar phloem unloading. Samples were taken between 1000 h and 1300 h. The arrows indicate where NaF and PCMB were included in the buffer solution. This graph shows that NaF and PCMB act rapidly in inhibiting phloem sugar unloading. The results shown are the mean values (n = 3 replicate berry-cups).

 
PCMB is a compound that modifies cysteine groups. It is lipid soluble and modifies thiol groups both at the surface and within the plasma membrane of root tissue (Wilkinson and Duncan, 1993), it has been used previously to inhibit enzyme activity (Wilkinson and Duncan, 1993; Wu et al., 2000).

Figure 4 shows that 2·5 mM PCMB significantly inhibits sugar phloem unloading in the grape berry, and that it continues to exert this inhibitory effect for up to 60 min after it has been removed from the MES buffer solution. These results demonstrate that phloem sugar unloading is a process that involves a sugar transporter and the intervention of enzymes (Fillon et al., 1999; Patrick and Offler, 1996). The inhibition of the sugar transporter produced by PCMB was not reversed by immersion in fresh MES buffer solution for 60 min.

Effect of water stress on phloem sugar unloading
Water stress can affect the rate of photosynthesis of plant, stomatal conductance, abscisic acid content and osmotic potential; it can also affect photoassimilate translocation (Rodrigues et al., 1993; Winkel and Rambal, 1993; Clifford, 1998; Flexas et al., 1998, 1999; Yakushiji, 1998; Escalona et al., 1999; Kobashi, 2000; Peterlunger et al., 2000). During maturation, moderate water stress retards secondary shoot growth without notably affecting photosynthetic activity (Carbonneau and Deloire, 2001), thus favouring the redistribution sugar in the berries and the perennial organs. However, severe water stress can actually inhibit the accumulation of sugar in grape berries. Sugar phloem unloading is the first step in the accumulation of sugar in the sink organ (Thorne, 1985; Oparka, 1990; Patrick, 1990, 1997). Figure 5 shows that the berries of vines subjected to water stress (equivalent to approx. {Psi}b {approx} –0·5 MPa) accumulated less sugar than the control vines ({Psi}b {approx} –0·2 MPa); this effect was observed principally after 1300 h. For any given berry volume, the sugar concentration in grapes subjected to water stress is less than that of the control. This finding concurs with earlier observations relating to the effect of water stress on vine photosynthesis (data not shown), and further demonstrates the suitability of the berry-cup system to study the effects of environmental factors or chemical inhibition on the accumulation of sugar in ripening grape berries.



View larger version (39K):
[in this window]
[in a new window]
  		Fig. 5. Effect of water stress on sugar unloading in grape berries 82 d after anthesis. The water stress applied to the vine appears to inhibit sugar phloem unloading in the grape berry during the day mainly after 1300 h. in relation with a significant reduction of photosynthesis activity. The results shown are the mean values (n = 3 replicate berry-cups) of sugar efflux (µg g–1 berry) from the peeled berry into the buffer solution.

 


   CONCLUSION
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSION
LITERATURE CITED
 
The berry-cup in vivo experimental system is a useful technique to study sugar phloem unloading and sugar accumulation in ripening grape berries. The content of sugar in the buffer solution is a realistic measure of phloem unloading following 60 min apoplastic purging. Thereafter, the buffer solution only becomes saturated with sugar after approx. 50 min. Thus, the optimum time period between buffer changes was taken to be 20 or 30 min (depending on the type of experiment). This experimental system can be used not only to study the mechanism of the sugar phloem unloading but also to study the effect of environmental factors or chemical inhibition on the accumulation of sugar in ripening grape berries. Sugar phloem unloading in ripening grape berries is shown to be via the apoplastic network and that the process requires a sugar transporter, the intervention of enzymes and a source of energy. This berry-cup technique is currently being used to investigate sugar unloading in relation to both the hydric status of the vine (water supply) and to the interception of sunlight (water demand).


   ACKNOWLEDGEMENTS
 
The authors thank Mary Kelly (Faculté de Pharmacie, Montpellier, France) for assisting with the English in this manuscript and for proofreading the text. We also thank Christian Bedes for technical assistance in the vineyard.


   LITERATURE CITED
TOP
 ABSTRACT
 INTRODUCTION
 MATERIALS AND METHODS
 RESULTS AND DISCUSSION
 CONCLUSION
 LITERATURE CITED
 

    Carbonneau A. 1998. Irrigation, vignoble et produit de la vigne. In: Tiercelin J-R, coordinator. Traité d’irrigation. Chapitre IV. Aspects Qualitatifs. Paris: Lavoisier Tec & Doc, 257–298.

    Carbonneau A, Deloire A. 2001. Plant organization based on source-sink relationship: new findings on developmental, biochemical and molecular responses to environment. In Roubelakis-Angelakis, KA, ed. Molecular Biology & Biotechnology of Grapevine. Dordrecht: Kluwer Academic Publishers, 263–280.

    Clifford SC. 1998. The role of solute accumulation, osmotic adjustment and changes in cell wall elasticity in drought tolerance in Ziziphus mauritiana (Lamk.). Journal of Experi mental Botany 49: 967–977.[Abstract/Free Full Text]

    Coombe BG. 1992. Research on development and ripening of the grape berry. American Journal of Enology and Viticulture 43: 101–110.[Abstract/Free Full Text]

    Damon S, Hewitt J, Nieder M, Bennett AB. 1988. Sink metabolism in tomato fruit. II. Phloem unloading and sugar uptake. Plant Physiology 87: 731–736.[Abstract/Free Full Text]

    Dreier LP, Hunter JJ, Ruffner HP. 1998. Invertase activity, grape berry development and cell compartmentation. Plant Physiology and Biochemistry 36: 865–872.[CrossRef]

    Escalona JM, Flexas J, Medrano H. 1999. Stomatal and non-stomatal limitations of photosynthesis under water stress in field-grown grapevines photosynthesis. Australian Journal of Plant Physiology 26: 421–433.[Web of Science]

    Fillon L, Ageorges A, Picaud S, Coutos-Thévenot P, Lemoine R, Romieu C, Delrot S. 1999. Cloning and expression of a hexose transporter gene expressed during the ripening of grape berry. Plant Physiology 120: 1083–1094.[Abstract/Free Full Text]

    Findlay N, Oliver KJ, Nii N, Coombe BG. 1987. Solute and accumulation by grape pericarp cell. Journal of Experimental Botany 189: 668–679.

    Flexas J, Escalona JM, Medrano H. 1998. Down-regulation of photosynthesis by drought under field conditions in grapevine leaves. Australian Journal of Plant Physiology 25: 893–900.[Web of Science]

    Flexas J, Escalona JM, Medrano H. 1999. Water stress induces different levels of photosynthesis and electron transport rate regulations in grapevines. Plant Cell Environment 22: 39–48.

    Gifford RM, Thorne JH. 1986. Phloem unloading in soybean seed coats: dynamics and stability of efflux into attached ‘empty ovules’. Plant Physiology 80: 464–469.[Abstract/Free Full Text]

    Ho LC. 1988. Metabolism and compartmentation of imported sugars in sink organs in relation to sink strength. Annual Review of Plant Physiology and Plant Molecular Biology 39: 55–378.

    Kobashi K. 2000. Abscisic acid content and sugar metabolism of peaches grown under water stress. Journal of the American Society for Horticultural Science 125: 425–428.

    Lü YM, Zhang DP, Yan HY. 1999. Sugar unloading mechanisms in the development of apple fruit. Acta Horticulturae Sinica 26 (3): 141–146 [in Chinese].

    Ofosu-Anim J, Yamaki S. 1994. Sugar content compartmentation and efflux in strawberry tissue. Journal of the American Society for Horticultural Science 119: 1024–1028.

    Ojeda H, Deloire A, Carbonneau A. 2001. Influence of water deficits on grape berry growth. Vitis 40: 141–145.[Web of Science]

    Oparka KJ. 1990. What is phloem unloading? Plant Physiology 94: 393–396.[Abstract/Free Full Text]

    Oparka KJ, Prior AM. 1987. 14C sucrose eflux from the perimedulla of growing potato tubers. Plant Cell Environment 10: 667–675.[CrossRef]

    Patrick JW. 1990. Sieve elements unloading: cellular pathway, mechanism and control. Physiologia Plantarum 78: 298–308.[CrossRef]

    Patrick JW. 1997. Phloem unloading: sieve element unloading and post-sieve element transport. Annual Review of Plant Biology 48: 191–222.[CrossRef][Web of Science]

    Patrick JW, Offler CE. 1996. Post-sieve element transport of photo assimilates in sink region. Journal of Experimental Botany 47 (Special Issue): 1165–1177.[Abstract]

    Peterlunger E, Buccella A, Iacono F, Bravdo BA. 2000. Physiological changes in grapevine during adjustment to water stress: ABA, leaf gas exchanges and root hydraulic conductivity. Acta-Horticulturae 526: 211–206.

    Robinson SP, Davies C. 2000. Molecular biology of grape berry ripening. Australian Journal of Grape and Wine Research 6: 175–188.

    Rodrigues ML, Chaves MM, Wendler R, David MM, Quick WE, Leegood RC, Stitt M, Pereira JS. 1993. Osmotic adjustment in water stressed grapevine leaves in relation to carbon assimilation. Australian Journal of Plant Physiology 20: 309–321.[Web of Science]

    Scholander PE, Hammel HT, Brandstreet ET, Hemmingsen EA. 1965. Sap pressure in vascular plants. Science 148: 339–346.[Abstract/Free Full Text]

    Thorne JH. 1985. Phloem unloading of C and N assimilates in developing seeds. Annual Reviews of Plant Physiology 36: 317–343.[CrossRef][Web of Science]

    Thorne JH, Rainbird RM. 1983. An in vivo technique for the study of phloem unloading in seed coats of developing soybean seeds. Plant Physiology 72: 268–271.[Abstract/Free Full Text]

    Wilkinson RE, Duncan RR. 1993. Calcium (45Ca2+) uptake in GP-10 sorghum root tips as influenced by hydrogen ion (H+) concentration and hours of exposure to H+-ATPase inhibitors. Journal of Plant Nutrition 16: 643–652.

    Winkel T, Rambal S. 1993. Influence of water stress on grapevines growing in the field: from leaf to whole-plant response. Australian Journal of Plant Physiology 20: 143–157.

    Wolswinkel P, Ammerlaan A. 1983. Phloem unloading in developing seeds of Vicia faba L. Planta 158: 205–215.[CrossRef][Web of Science]

    Wu LJ, Huang WC, Sung HY, Wu LJ, Huang WC, Sung HY. 2000. Partial purification and characterization of soluble acid invertase from sweet potato suspension cells. Food Science, Agricultural Chemistry 2(1): 49–54.

    Xia GH. 1999. Mechanisms of sugar unloading and metabolism in grape berries. Thesis, Agricultural University of China, Beijing [in Chinese].

    Yakushiji H. 1998. Sugar accumulation and partitioning in satsuma mandarin tree tissues and fruit in response to drought stress. Journal of the American Society for Horticultural Science 123: 719–726.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 J Exp BotHome page
M. Krasnow, M. Matthews, and K. Shackel
Evidence for substantial maintenance of membrane integrity and cell viability in normally developing grape (Vitis vinifera L.) berries throughout development
J. Exp. Bot., March 1, 2008; 59(4): 849 - 859.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Bot.Home page
E. Etxeberria, P. Gonzalez, and J. Pozueta-Romero
Mannitol-enhanced, fluid-phase endocytosis in storage parenchyma cells of celery (Apium graveolens; Apiaceae) petioles
Am. J. Botany, June 1, 2007; 94(6): 1041 - 1045.
[Abstract] [Full Text] [PDF]

Home page
 ANN BOT (LOND)Home page
K. P. Gaffal, G. J. Friedrichs, and S. El-Gammal
Ultrastructural Evidence for a Dual Function of the Phloem and Programmed Cell Death in the Floral Nectary of Digitalis purpurea
Ann. Bot., April 1, 2007; 99(4): 593 - 607.
[Abstract] [Full Text] [PDF]

Home page
 Plant Physiol.Home page
F. Goes da Silva, A. Iandolino, F. Al-Kayal, M. C. Bohlmann, M. A. Cushman, H. Lim, A. Ergul, R. Figueroa, E. K. Kabuloglu, C. Osborne, et al.
Characterizing the Grape Transcriptome. Analysis of Expressed Sequence Tags from Multiple Vitis Species and Development of a Compendium of Gene Expression during Berry Development
Plant Physiology, October 1, 2005; 139(2): 574 - 597.
[Abstract] [Full Text] [PDF]

Home page
 Plant Physiol.Home page
T. E. Sondergaard, A. Schulz, and M. G. Palmgren
Energization of Transport Processes in Plants. Roles of the Plasma Membrane H+-ATPase
Plant Physiology, September 1, 2004; 136(1): 2475 - 2482.
[Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow Content Snapshot
Right arrow Content Select
Right arrow All Versions of this Article:
92/4/523    most recent
mcg159v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (13)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by WANG, Z.-P.
Right arrow Articles by LOPEZ, F.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by WANG, Z.-P.
Right arrow Articles by LOPEZ, F.
Agricola
Right arrow Articles by WANG, Z.-P.
Right arrow Articles by LOPEZ, F.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?