Structural and transcriptional analysis of the self-incompatibility locus of almond: identification of a pollen-expressed F-box gene with haplotype-specific polymorphism.
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Gametophytic self-incompatibility in Rosaceae, Solanaceae, and Scrophulariaceae is controlled by the S locus, which consists of an S-RNase gene and an unidentified "pollen S" gene. An approximately 70-kb segment of the S locus of the rosaceous species almond, the S haplotype-specific region containing the S-RNase gene, was sequenced completely. This region was found to contain two pollen-expressed F-box genes that are likely candidates for pollen S genes. One of them, named SFB (S haplotype-specific F-box protein), was expressed specifically in pollen and showed a high level of S haplotype-specific sequence polymorphism, comparable to that of the S-RNases. The other is unlikely to determine the S specificity of pollen because it showed little allelic sequence polymorphism and was expressed also in pistil. Three other S haplotypes were cloned, and the pollen-expressed genes were physically mapped. In all four cases, SFBs were linked physically to the S-RNase genes and were located at the S haplotype-specific region, where recombination is believed to be suppressed, suggesting that the two genes are inherited as a unit. These features are consistent with the hypothesis that SFB is the pollen S gene. This hypothesis predicts the involvement of the ubiquitin/26S proteasome proteolytic pathway in the RNase-based gametophytic self-incompatibility system. (+info)
Effects of the experimental blockage of the major veins on hydraulics and gas exchange of Prunus laurocerasus L. leaves.
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The impact of leaf vein blockage on leaf hydraulic conductance (K(L)), gas exchange (g(L)) and water potential (Psi(L)) was studied in Prunus laurocerasus L., a broad-leaved evergreen. For this purpose, leaves were measured for the three variables above, either with an intact leaf blade (controls) or with the midrib cut a third of the way up (cut a), or with the midrib cut at three different points and the first-order veins cut through near their insertion to the midrib (cut b), or with the midrib cut at 2 mm from the leaf base (cut c). All the cut surfaces were sealed with cyanoacrylate. A serial decrease of K(L) was recorded from cut a to cut c with respect to that measured for the controls, i.e. a K(L) loss of about 37% (cut a), 57% (cut b) and 87% (cut c). A positive linear relationship appeared to exist between g(L) and K(L) with a high correlation coefficient (r(2)=0.99) and a high statistical significance (P <0.01). Even under a severe drop in K(L) (as that induced by cut c), leaf water potential remained approximately constant and not statistically different from Psi(L) measured for the controls. In fact, Psi(L) ranged between -0.83 and -0.98 MPa, i.e. within the cavitation threshold of leaves in terms of the critical Psi(L) inducing a significant production of ultrasound acoustic emissions which was -0.94+/-0.09 MPa. The conclusion was that stomata were very sensitive to changes in K(L) and that stomatal closure led to the homeostatic maintenance of Psi(L) and cavitation avoidance. (+info)
Purification and characterization of a beta-galactosidase from peach (Prunus persica).
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A beta-galactosidase (EC 3.2.1.23) from peach (Prunus persica cv Mibackdo) was purified and characterized. The purified peach beta-galactosidase was 42 kDa in molecular mass and showed high enzyme activity against a the beta-galactosidase substrate, rho-nitrophenyl-beta-D-galactopyranoside. The Km and Vmax values of the enzyme activity of the peach beta-galactosidase were 5.16 and 0.19 mM for rho-nitrophenyl-beta-D-galactopyranoside mM/h, respectively. The optimum pH of the enzyme activity was pH 3.0, but it was relatively stable from pH 3.0-10.0. The temperature optimum was 50 degrees C. The enzyme activities were not improved in the buffers that contained Ca2+, Cu2+, Zn2+, and Mg2+, which indicates that the purified peach beta-galactosidase did not require these cations as co-factors. However, the enzyme was completely inhibited by Hg2+. The purified protein was cross-reacted with an antibody against the persimmon fruit beta-galactosidase. A further comparison of the N-terminal amino acid sequence of the purified protein showed high homologies to those of beta-galactosidase in apple (87%), persimmon (80%), and tomato (87%). Therefore, enzymatic, immunological, and molecular evidences in this study indicate that the purified 42-kDa protein is a peach beta-galactosidase. (+info)
Medicinal flowers. VIII. Radical scavenging constituents from the flowers of Prunus mume: structure of prunose III.
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The methanolic extract and its fractions from the fresh flowers of Prunus mume SIEB. et ZUCC. were found to show scavenging effects on 1,1-diphenylpicryl-2-hydrazyl (DPPH) radical and superoxide. The fragrance constituents of P. mume were analyzed by GC-MS and a new polyacylated sucrose, prunose III, was isolated from the ethyl acetate-soluble fraction. The structure of prunose III was determined on the basis of chemical and physicochemical evidence as 4,3',4',6'-tetra-O-acetyl-6-O-p-coumaroylsucrose. In addition, the scavenging effects of the principal constituents on DPPH radical and superoxide were examined. (+info)
Cloning, expression, and characterization of sorbitol transporters from developing sour cherry fruit and leaf sink tissues.
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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. (+info)
Growth and photosynthesis of Japanese flowering cherry under simulated microgravity conditions.
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The photosynthetic rate, the leaf characteristics related to photosynthesis, such as the chlorophyll content, chlorophyll a/b ratio and density of the stomata, the leaf area and the dry weight in seedlings of Japanese flowering cherry grown under normal gravity and simulated microgravity conditions were examined. No significant differences were found in the photosynthetic rates between the two conditions. Moreover, leaf characteristics such as the chlorophyll content, chlorophyll a/b ratio and density of the stomata in the seedlings grown under the simulated microgravity condition were not affected. However, the photosynthetic product of the whole seedling under the simulated microgravity condition increased compared with the control due to its leaf area increase. The results suggest that dynamic gravitational stimulus controls the partitioning of the products of photosynthesis. (+info)
Consumption of cherries lowers plasma urate in healthy women.
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To assess the physiologic effects of cherry consumption, we measured plasma urate, antioxidant and inflammatory markers in 10 healthy women who consumed Bing sweet cherries. The women, age 22-40 y, consumed two servings (280 g) of cherries after an overnight fast. Blood and urine samples were taken before the cherry dose, and at 1.5, 3 and 5 h postdose. Plasma urate decreased 5 h postdose, mean +/- SEM = 183 +/- 15 micro mol/L compared with predose baseline of 214 +/- 13 micro mol/L (P < 0.05). Urinary urate increased postdose, with peak excretion of 350 +/- 33 micro mol/mmol creatinine 3 h postdose compared with 202 +/- 13 at baseline (P < 0.01). Plasma C-reactive protein (CRP) and nitric oxide (NO) concentrations had decreased marginally 3 h postdose (P < 0.1), whereas plasma albumin and tumor necrosis factor-alpha were unchanged. The vitamin C content of the cherries was solely as dehydroascorbic acid, but postdose increases in plasma ascorbic acid indicated that dehydroascorbic acid in fruits is bioavailable as vitamin C. The decrease in plasma urate after cherry consumption supports the reputed anti-gout efficacy of cherries. The trend toward decreased inflammatory indices (CRP and NO) adds to the in vitro evidence that compounds in cherries may inhibit inflammatory pathways. (+info)
Characterization of the S-RNase promoters from sweet cherry (Prunus avium L.).
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Genomic DNA fragments containing the S(3)-, S(4)-, and S(6)-RNase genes were isolated from the sweet cherry (Prunus avium L.) and sequenced. Comparison of the 5'-flanking sequences of these three S-RNases indicated that a highly conserved region (designated CR) existed just upstream from the putative TATA boxes. We postulate that CR contains cis-regulatory element(s) involved in pistil expression. To examine the activity of the isolated S-RNase promoters of sweet cherry in the pistil, we transiently introduced approximately 650-bp fragments of the S(4)- and S(6)-RNase promoters fused to beta-glucuronidase (GUS) gene into the pistil of the petunia using a particle bombardment technique. Histochemical analysis showed that the 5'-flanking region of each S-RNase was active in the pistil. This suggests that cis-regulatory element(s) for pistil-specific expression may exist(s) within the 650-bp region upstream from the TATA box in the sweet cherry S-RNase promoter. (+info)