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At least 163 records · Page 9Linked to original sources
PubMed1999

Technical Advance: Confocal measurement of the three-dimensional size and shape of plant parenchyma cells in a developing fruit tissue.

Parenchyma cells from the inner mesocarp of a grape berry (Vitis vinifera L. cv. Chardonnay) were visualised in three-dimensions within a whole mount of cleared, stained tissue using confocal laser scanning microscopy and digital image reconstruction. The whole berry was fixed, bisected longitudinally, cleared in methyl salicylate, stained with safranin O and mounted in methyl salicylate. Optical slices were collected at 1.0 µm intervals to a depth of 150 µm. Neighbouring z-series were joined post-collection to double the field-of-view. Attenuation at depth of the fluorescent signal from cell walls was quantified and corrected. Axial distortion due to refractive index mismatch between the immersion and mounting media was calibrated using yellow-green fluorescent microspheres and corrected. Transmission electron microscopy was used to correct fluorescent measurements of cell wall thickness. Digital image reconstructions of wall-enclosed spaces enabled cells to be rendered as geometric solids of measurable surface area and volume. Cell volumes within the inner mesocarp tissue of a single grape berry exhibited a 14-fold range, with polysigmoidal distribution and groupings around specific size classes. Cell shape was irregular and the planes of contact were rarely flat or simple. Variability in cell shape was indicated by the range in surface area to volume ratios, from 0.080 to 0.198 µm-1. Structural detail at the internal surface of the cell wall was apparent. The technique is applicable to a wide range of morphometric analyses in plant cell biology, particularly developmental studies, and reveals details of cell size and shape that were previously unattainable.

Journal Article↗
PubMed1987

Intracellular pH of Cotton Embryos and Seed Coats during Fruit Development Determined by P Nuclear Magnetic Resonance Spectroscopy.

The pH of the phosphate-containing compartments of developing cotton seed coat and embryo tissues was determined by means of (31)P nuclear magnetic resonance spectroscopy. The pH values of these tissues varied as a function of developmental age. From 27 to approximately 38 days postanthesis, a strong pH differential existed between the two tissues; the seed coat was up to 1.4 pH units more acid than developing cotton embryos. The pattern of pH values found with this technique agrees with pH values of tissue homogenates in distilled water. The results confirm an earlier suggestion that seed coat cells are more acidic than embryo cells during key developmental stages of the seed. The pH differential between these two tissues causes abscisic acid to diffuse from seed coats to embryos against its apparent concentration gradient to prevent viviparous germination, despite a higher abscisic acid concentration in the embryo.

Journal Article↗
PubMed1988

Mechanism of export of organic material from the developing fruits of pea.

Pisum sativum L. fruits export a small quantity of radiolabeled substances to other plant parts after the fruits are allowed to photosynthesize in the presence of (14)CO(2). Export was uninhibited by peduncle girdling suggesting an apoplastic route for transport of material, presumably by ;reverse' flow in the peduncle xylem. To determine if any diurnal water potential gradient formed between pea leaves and fruit might be responsible for the observed export, the water potentials of the various organs were monitored over 24 hours. Water potential differences of up to 7.5 bars existed between leaves and fruit in long photoperiods, and up to 2.5 bars in short photoperiods. Pulses of (14)CO(2) labeling indicated that initial delivery of exported label was to ;transpirational sinks,' with subsequent redistribution of label to metabolic sinks. Export to the apical bud appeared to be direct via the xylem. Application of membrane-impermeable inulin to a surgically opened seed coat ;cup' resulted in export mainly to the subtending leaf with little redistribution. Simultaneous application of sucrose to the seed coat resulted in more extensive distribution of the sucrose, consistent with reloading of the sucrose into mature leaf phloem. Thus, export of material from fruits appears to occur via a xylem pathway in response to transpirationally derived water potential gradients.

Journal Article↗
PubMed2000

Molecular characterization of the expression of distinct classes of cyclins during the early development of tomato fruit.

Early fruit development in tomato (Lycopersicon esculentum Mill.) proceeds from two distinct phases of growth, essentially cell division and cell expansion. In this study, we investigated the expression characteristics of the key cell-cycle regulators, mitotic and G1 cyclins, during tomato fruit development. We isolated six genes designated Lyces;CycA1;1, Lyces;CycA2;1, Lyces; CycA3;1, Lyces;CycB1:1 and Lyces;CycB2;1 encoding tomato mitotic cyclins, and Lyces;CycD3;1 encoding a G1 cyclin. The accumulation of transcripts was predominantly associated with mitotically active organs: developing fruits, young leaves and roots, and with cell-suspension cultures under appropriate sugar feeding conditions. Transcripts for all the isolated cyclin genes could be detected in the epidermis and pericarp of fruit tissues where some slight mitotic activity still remained at the onset of ripening. However, Lyces;CycA3;1 and Lyces;CycD3;1 were expressed in the gel tissue at the late stage of fruit development, suggesting that they are involved in endoreduplication of the differentiated and giant cells of the gel tissue.

Amino Acid Sequence↗
PubMed2004

Developing pineapple fruit has a small transcriptome dominated by metallothionein.

In a first step toward understanding the molecular basis of pineapple fruit development, a sequencing project was initiated to survey a range of expressed sequences from green unripe and yellow ripe fruit tissue. A highly abundant metallothionein transcript was identified during library construction, and was estimated to account for up to 50% of all EST library clones. Library clones with metallothionein subtracted were sequenced, and 408 unripe green and 1140 ripe yellow edited EST clone sequences were retrieved. Clone redundancy was high, with the combined 1548 clone sequences clustering into just 634 contigs comprising 191 consensus sequences and 443 singletons. Half of the EST clone sequences clustered within 13.5% and 9.3% of contigs from green unripe and yellow ripe libraries, respectively, indicating that a small subset of genes dominate the majority of the transcriptome. Furthermore, sequence cluster analysis, northern analysis, and functional classification revealed major differences between genes expressed in the unripe green and ripe yellow fruit tissues. Abundant genes identified from the green fruit include a fruit bromelain and a bromelain inhibitor. Abundant genes identified in the yellow fruit library include a MADS box gene, and several genes normally associated with protein synthesis, including homologues of ribosomal L10 and the translation factors SUI1 and eIF5A. Both the green unripe and yellow ripe libraries contained high proportions of clones associated with oxidative stress responses and the detoxification of free radicals.

Ananas↗
PubMed1985

Economy of water, carbon, and nitrogen in the developing cowpea fruit.

The nutritional economy of the fruit of cowpea (Vigna unguiculata (L.) Walp cv Vita 3) was assessed quantitatively from intake and utilization of carbon, nitrogen, and water. Fruits failed to make net gains of CO(2) from the atmosphere during daytime, although pod photosynthesis did play a role in the fruit's carbon economy by refixing a proportion of the fruit's respired CO(2). Of every 100 units by weight of carbon entering the fruit, 70.4 were finally incorporated into seeds, 10.3 remained as nonmobilizable material in pod walls, and the remaining 19.3 were lost in fruit respiration. Phloem supplied 97% of the fruit's carbon and 72% of its nitrogen. The xylem contribution of nitrogen occurred mainly in early growth. Ninety-six% of the fruit's nitrogen was incorporated into seeds, approximately 10% of this mobilized from the senescing pod. The mean transpiration ratio of the fruit was very low-8 milliliters water transpired per gram dry matter accumulated. Models of carbon, nitrogen, and water flow were constructed for the two consecutive 11 day periods of fruit development, and indicated a considerably greater entry of water through xylem and phloem than could be accounted for in changes in fruit tissue water and transpiration loss. This discrepancy was greater in the second half of fruit growth and was interpreted as evidence that a significant fraction of the water entering the fruit through phloem cycled back to the parent plant via the xylem.

Journal Article↗
PubMed2003

Cloning, expression, and characterization of sorbitol transporters from developing sour cherry fruit and leaf sink tissues.

The acyclic polyol sorbitol is a primary photosynthetic product and the principal photosynthetic transport substance in many economically important members of the family Rosaceace (e.g. almond [Prunus dulcis (P. Mill.) D.A. Webber], apple [Malus pumila P. Mill.], cherry [Prunus spp.], peach [Prunus persica L. Batsch], and pear [Pyrus communis]). To understand key steps in long-distance transport and particularly partitioning and accumulation of sorbitol in sink tissues, we have cloned two sorbitol transporter genes (PcSOT1 and PcSOT2) from sour cherry (Prunus cerasus) fruit tissues that accumulate large quantities of sorbitol. Sorbitol uptake activities and other characteristics were measured by heterologous expression of PcSOT1 and PcSOT2 in yeast (Saccharomyces cerevisiae). Both genes encode proton-dependent, sorbitol-specific transporters with similar affinities (K(m) sorbitol of 0.81 mM for PcSOT1 and 0.64 mM for PcSOT2). Analyses of gene expression of these transporters, however, suggest different roles during leaf and fruit development. PcSOT1 is expressed throughout fruit development, but especially when growth and sorbitol accumulation rates are highest. In leaves, PcSOT1 expression is highest in young, expanding tissues, but substantially less in mature leaves. In contrast, PcSOT2 is mainly expressed only early in fruit development and not in leaves. Compositional analyses suggest that transport mediated by PcSOT1 and PcSOT2 plays a major role in sorbitol and dry matter accumulation in sour cherry fruits. Presence of these transporters and the high fruit sorbitol concentrations suggest that there is an apoplastic step during phloem unloading and accumulation in these sink tissues. Expression of PcSOT1 in young leaves before completion of the transition from sink to source is further evidence for a role in determining sink activity.

Amino Acid Sequence↗