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Genetic mapping of the evergrowing gene in peach [Prunus persica (L.) Batsch].

In temperate locations, terminal apices on evergrowing (also called evergreen) peach trees keep growing in winter until killed by low temperatures, while the lateral buds go into dormancy. A recessive allele of a single gene (evergrowing or evg) controls this trait in peach. The amplified fragment length polymorphism (AFLP) technique and bulked segregant analysis were applied to construct a local genetic linkage map for the evg gene from the cross Empress op op dwarf x Evergrowing (P.I. 442380). This map, comprising nine AFLP markers and the evg locus, covers a total genetic distance of 79.3 cM. Four dominant AFLP markers (EAT/MCAC, ETT/MCCA2, EAT/MCTA, and ETT/MACC) were linked to the evg locus at distances of 1, 5.3, 6.7, and 11.7 cM, respectively. EAT/MCAC and EAT/MCTA were converted into polymorphic sequence-tagged sites. Microsatellite markers in the evg region were developed from peach bacterial artificial chromosome (BAC) clones that hybridized to the AFLP marker fragments. Using three microsatellite anchor markers (pchgms12, pchgms17, and pchgms19), the local genetic linkage map was integrated into one minor linkage group of a previously constructed peach rootstock genetic linkage map. Three AFLP markers from the rootstock genetic linkage map were found linked to the evg locus.

Base Sequence↗
PubMed2006

Ethylene-regulation of fruit softening and softening-related genes in peach.

To investigate the role of ethylene in peach fruit softening during ripening, stony hard peach fruit, in which ethylene production is suppressed during ripening, were treated with various concentrations of ethylene. There was no noticeable decrease in flesh firmness without ethylene treatment, while applied ethylene, in the range 0.1-100 microl l(-1), resulted in fruit softening. Furthermore, the fruit softened more rapidly when the applied ethylene concentration was higher. When ethylene treatment was interrupted, the degree of softening was greatly reduced. These results indicated that continuous ethylene treatment was required for the initiation and progression of fruit softening and that ethylene concentration is also an important factor in regulating the rate of softening. Eight genes, which putatively encode cell wall metabolism-related proteins, were investigated for mRNA accumulation patterns in the two different softening phenotypes of melting and stony hard peaches. All of the mRNAs investigated accumulated in fruit of the melting-flesh "Akatsuki" during ripening. By contrast, in the stony hard-flesh "Manami", the mRNAs for a putative endopolygalacturonase (PpPG), an alpha-L-arabinofuranosidase/beta-xylosidase (PpARF/XYL), and an expansin (PpExp3) showed either much lower levels or did not accumulate, and were identified as softening-related genes. Interruption of ethylene treatment indicated that these genes were regulated at the transcriptional level, and quickly responded to the presence or absence of ethylene before the softening response occurred, suggesting that ethylene directly regulates the transcription of these softening-related genes. These results suggested that cell wall metabolism, causing a rapid loss of firmness in peach fruit, may be controlled by ethylene at the transcriptional level.

Cell Wall↗
PubMed1998

Genomic structure of three phenotypically different isolates of peach latent mosaic viroid: implications of the existence of constraints limiting the heterogeneity of viroid quasispecies.

The peach latent mosaic viroid (PLMVd) is used to study the interactions between a viroid containing hammerhead ribozymes and its natural host, peach. To gain insight into the molecular basis of the phenotypic effects observed upon viroid infection, sequence variants from three PLMVd isolates that differ in symptom expression on the peach indicator GF-305 have been characterized. Analysis of the primary structures of a total of 29 different sequence variants derived from a severe and two latent isolates has revealed a large number of polymorphic positions in the viroid molecule. The variability pattern indicates that preservation of the stability of both hammerhead structures and conservation of a branched secondary structure of the viroid molecule may be factors limiting sequence heterogeneity in PLMVd. Moreover, compensatory mutations in two hairpin loops of the proposed secondary structure, suggesting that a pseudoknot-like interaction may exist between them, have also been observed. Phylogenetic analysis has allowed the allocation of PLMVd molecules into three major groups. This clustering does not strictly correlate with the source isolate from which the variants were obtained, providing insights into the complex mixture of molecules which make up each isolate. Bioassays of individual PLMVd sequence variants on GF-305 peach seedlings have shown that the biological properties of the PLMVd isolates may be correlated with both the complexity of their viroid populations and the presence of specific sequence variants.

Base Sequence↗
PubMed1996

[Effect of supplementation with peach palm as source of vitamin A: study with rats].

The effect of supplementation with peach palm (Bactris gasipaes H.B.K.), as an alternative source of vit. A, in the regional diet of Manaus, AM, Brazil, in which the pulp was cooked and transformed into flour, was studied. The biological trial involved rats which were depleted in zinc and vitamin A, followed by repletion using the regional diet (RD), RD plus peach palm and RD plus vitamin A. The parameters used to determine the utilization of vitamin A were the vitamin A concentrations in the liver and plasma, and the growth of the animals. The diet was prepared according to the data of Shrimpton and Giugliano for families earning less than two legal minimum salaries. Adult post-partum rats were used, with six male pups each, which received a diet based on casein washed with 1% EDTA, without the addition of zinc or vitamin A for a period of 25 days, for the purpose of obtaining newly-weaned animals which were deficient in Zn and Vit.A. A control group received a diet also based on casein washed with 1% EDTA, but with all the nutrients in the quantities suggested by the Committee on Laboratory Animal Diets. The repletion period of the newly-weaned rats was of 30 days and the experimental design was entirely randomized with four groups of eight rats each. The diet supplementation followed the recommendations of the Committee on Laboratory Animal Diets. At the end of the experiment, it was observed that rats which consumed the diet based on the regional diet of Manaus supplemented with either peach palm or vitamin A showed a significantly greater concentration of vitamin A in the liver, 43.3 +/- 6.5 micrograms/g, 42.0 +/- 4.3 micrograms/g, respectively in relation to the regional diet, 5.5 +/- 1.1 micrograms/g (p < 0.05). The amount of zinc present in the regional diet, 10.7 mg per day, was bioavailable as determined by the concentration of zinc in the femurs. The results suggest that the regional diet of Manaus needs to be supplemented with vitamin A to maintain the hepatic reserves, and that such supplementation can be accomplished with peach palm, an abundant local commodity.

Analysis of Variance↗
PubMed2002

Managing Brachycaudis persicae (Homoptera: Aphididae) during peach orchard establishment.

We investigated whether preplant root dips or postplant sprays or drenches could be used to control the black peach aphid, Brachycaudus persicae (Passerini), on young peach trees. In greenhouse trials, B. persicae died after being placed on peach trees that had their roots dipped in imidacloprid before planting. All rates (0.8, 1.6, and 3.2 ml/liter of water) tested controlled this aphid. B. persicae died faster on trees dipped in imidacloprid (1.6 ml/liter of water) for 5 min before planting than on trees dipped for 2 s. Aphids eventually died on all treated trees. Approximately 50% of untreated trees died from B. persicae infestations in greenhouse studies. Results from afield experiment show that peach trees root-dipped in imidacloprid before planting or drenched with imidacloprid after planting eliminate B. persicae infestations and prevent root colonization for at least 1 yr.

Agriculture↗
PubMed2006

Comparative survival rates of oriental fruit moth (Lepidoptera: Tortricidae) larvae on shoots and fruit of apple and peach.

Studies were designed to examine the effects of host plants on oriental fruit moth, Grapholita molesta (Busck) (Lepidoptera: Tortricidae), survival. G. molesta larval survival in the orchard was comparable between apple (Malus spp.) and peach (Prunus spp.) shoots, indicating that both host species can harbor large larval populations during the early season. G. molesta larvae used multiple shoots for feeding and development on peaches but usually only damaged single shoots in apple. Survival differences were present between peach and apple fruit, but this survival was affected by fruit maturity level. Generally, larval survival higher was in ripening peach fruit than in green, immature apple fruit. Larval survival varied among several apple cultivars, indicating that cultivar-level variability needs to be considered. These host-associated effects may impact efforts to predictively model G. molesta populations in commercial orchards where multiple host plant species, or different cultivars of the same species are often grown in proximity. Thus, host-associated dynamics should be included into future population models that underlie management programs.

Animals↗
PubMed2005

Changes in aroma volatile compounds and ethylene production during "Hujingmilu" peach (Prunus persica L.) fruit development.

Changes in ethylene production rate, respiration rate, and aroma volatile composition was determined from the immature to mature stage in "Hujingmilu" peach (Prunus presica) fruit. Flesh firmness, fruit size, ground color of skin, and total soluble solids (TSS), titratable acidity (TA) in juice were analyzed, and ACC, ACC synthase and ACC oxidase activities were measured. With the increase of fruit maturity, fruit size, L* value, and TSS and major reducing sugar contents increased, whereas fruit firmness, skin hue angle (h degrees ), and juice TA and organic acid contents decreased. In immature fruits, a C(6)-aldehydes (trans-2-hexenal) and C(6)-alcohols (cis-3-hexenol) were the major components, corresponding to the low ethylene production and high respiration rates. With increasing of fruit maturity, the C(6)-C(12) lactonic compounds, particularly gamma- and delta-lactones became the dominant volatile constituents, which increased significantly at the climacteric stage. These facts suggest that ethylene production may be involved in the regulation of lactones production in maturing peach fruit. The activity of ACC synthase in the mesocarp declined during the climacteric rise of ethylene. ACC level and ACC oxidase activity in mesocarp were consistent with the onset of ethylene production in fruit. Major aroma volatiles are thought to form in conjunction with the initiation of climacteric rises in respiration and ethylene production. Detection of changes in aroma volatile compound synthesis rate in peach may be useful as index of maturity reflecting the current physiological stage of peach fruit development.

Amino Acid Oxidoreductases↗
PubMed2005

Detection and epidemiological characteristics of peach latent mosaic viroid in Tunisia.

A rapid and sensitive assay was developed for the detection and identification of Peach latent mosaic viroid (PLMVd) by reverse transcription-polymerase chain reaction (RT-PCR) in infected tissues from Tunisian orchards. The test was initially performed by using total RNA preparations from selected isolates and then applied on total RNA preparations from leaf or bark tissues of fruit trees collected in 2003 in 20 orchards in the North of Tunisia and the Sahel. PLMVd occurred in peach and pear trees. The identity of the detected viroid was confirmed by comparison of its sequence with other isolates previously characterized. The test was then simplified by direct use of diluted crude plant extracts. The results obtained from crude sap extracts of leaves or bark tissues are identical to those obtained from total RNA preparations. Epidemiological characteristics of PLMVd on peach trees have been investigated. A survey of peach trees was carried out in 32 orchards in May 2004. The obtained results showed that (1) PLMVd is highly and equally present in several regions of the north of Tunisia rather than the central, the Sahel and the southern regions, (2) infection percentage increases with the age of the tree and (3) the studied cultivars are classified into three groups of sensitivity.

Gene Amplification↗
PubMed2002

Microsatellite variability in peach [ Prunus persica (L.) Batsch]: cultivar identification, marker mutation, pedigree inferences and population structure.

A collection of 212 peach and nectarine cultivars covering a wide variation of the species were studied with 16 polymorphic single-locus microsatellite, or simple-sequence repeat (SSR), markers. The average number of alleles per locus was 7.3, 35% of the cultivar x locus combinations analyzed were heterozygous and 87% of the cultivars studied could be individually identified. Most of the groups where two or more cultivars had the same SSR fingerprint included known peach mutants or possible synonymies. Pedigree information was tested with the SSR data. Five unexpected genotypes, due to a mutation at five SSR loci were found when comparing the SSR fingerprint of 14 known mutant cultivars and putative synonymous cultivars. The pedigree data were not consistent with the observed data in 11 out of 38 cases that could be analyzed. The group of non-melting fruit flesh cultivars, generally used by the canning industry, was more variable and genetically distant than the rest of the cultivars tested. Based on their level of homozygosity it was possible to separate those cultivars that were obtained by modern breeding technologies from those that were selected from traditional orchards after generations of seed propagation. The former had a distribution of genotypic frequencies close to a random mating model while the latter had a higher level of homozygosity. The implications of these data for the use of SSR fingerprints in breeder's rights protection and peach breeding are discussed.

Heterozygote↗
PubMed2003

Genetic linkage maps of two apricot cultivars ( Prunus armeniaca L.) compared with the almond Texas x peach Earlygold reference map for Prunus.

Several genetic linkage maps have been published in recent years on different Prunus species suggesting a high level of resemblance among the genomes of these species. One of these maps (Joobeur et al., Theor Appl Genet 97:1034-1041 [(1998); Aranzana et al., Theor Appl Genet 106:819-825 (2002b)] constructed from interspecific almond Texas x peach Earlygold F(2) progeny (TxE) was considered to be saturated. We selected 142 F(1) apricot hybrids obtained from a cross between P. armeniaca cvs. Polonais and Stark Early Orange for mapping. Eighty-eight RFLP probes and 20 peach SSR primer pairs used for the 'reference map' were selected to cover the eight linkage groups. One P. davidiana and an additional 14 apricot simple sequence repeats (SSRs) were mapped for the F(1) progeny. Eighty-three amplified fragment length polymorphisms were added in order to increase the density of the maps. Separate maps were made for each parent according to the 'double pseudo-testcross' model of analysis. A total of 141 markers were placed on the map of Stark Early Orange, defining a total length of 699 cM, and 110 markers were placed on the map of Polonais, defining a total length of 538 cM. Twenty-one SSRs and 18 restriction placed in the TxE map were heterozygous in both parents (anchor loci), thereby enabling the alignment of the eight homologous linkage groups of each map. Except for 15 markers, most markers present in each linkage group in apricot were aligned with those in TxE map, indicating a high degree of colinearity between the apricot genome and the peach and almond genomes. These results suggest a strong homology of the genomes between these species and probably between Prunophora and Amygdalus sub-genera.

Chromosome Mapping↗
PubMed2004

Analysis of genotypic variation in fruit flesh total sugar content via an ecophysiological model applied to peach.

A simulation model of the evolution of total sugar content ( C(TS)) in fruit was developed in order to describe the within- and between-genotype variation of C(TS) observed in a peach ( Prunus persica (L.) Batsch) breeding population. The parameter k defines the ratio of carbon used for synthesizing compounds other than sugars for each genotype. Model input variables are dry flesh growth rate and fresh flesh mass of fruit. We estimated k for 137 peach and nectarine genotypes derived from a clone of a wild peach ( Prunus davidiana) by three generations of crosses with commercial nectarine varieties. We tested the predictive quality of the model on independent datasets. Despite an underestimation of the observed C(TS), the correlation between observations and predictions was suitable (0.72). Spearman correlation coefficients between 2001 and 2002 for model input variables and parameter k were higher than for C(TS). None of the three components assimilation supply to the fruit, metabolism, or dilution, seemed to have a greater relative effect on C(TS) variation than the others. Indeed, C(TS) variation seemed to result from the balance between the three components. The interest of this approach, which consists of dissecting traits into components via an ecophysiological model, for breeding strategy and for sugar accumulation studies are discussed.

Biological Evolution↗
PubMed2026

Benzoic acid inhibits peach root growth and lateral root emergence by disrupting auxin homeostasis through salicylic acid accumulation.

We established a non-sterile root transformation system in peach seedlings. Using this system, we demonstrated that BA treatment inhibits plant growth and lateral root emergence by SA-mediated disruption of auxin distribution. Allelopathic autotoxins, particularly benzoic acid (BA), are recognized as primary contributors to peach (Prunus persica) replant disease; however, the molecular mechanisms by which BA disrupts root development remain poorly understood. BA treatment significantly reduced stem and root length and inhibited lateral root emergence without affecting lateral root initiation. To investigate the underlying mechanism at cellular resolution, we established a non-sterile Agrobacterium rhizogenes-based root transformation system achieving 27.11% transformation efficiency. Auxin biosynthesis (PpYUC10), influx transport (PpAUX1), and response (PpARF19) genes were markedly downregulated following BA treatment. Transgenic roots expressing the DR5::GUS auxin reporter exhibited reduced DR5 activity in root tips and suppressed expression in tissues surrounding lateral root primordia, indicating impaired auxin signaling at both developmental sites. Hormone profiling revealed a non-significant trend toward reduced auxin metabolites alongside significant accumulation of salicylic acid (SA), an auxin-antagonistic hormone, and its storage conjugate SA 2-O-&#x3b2;-glucoside. Supporting a causal role for SA, exogenous SA phenocopied BA-induced root growth inhibition, whereas co-treatment with IAA or the SA-biosynthesis inhibitor aminoindan-1-phosphonic acid (AIP) significantly rescued lateral root number and root fresh weight. Multi-treatment RNA-seq identified "response to auxin" and "response to salicylic acid" as the most enriched GO terms in BA-treated roots, and AIP treatment restored the expression of key auxin-related genes while reversing BA-induced SA-pathway changes. Together, these findings suggest that BA-induced SA accumulation suppresses auxin biosynthesis, transport, and signaling, thereby inhibiting peach root growth and lateral root emergence. This study elucidates the molecular basis of BA autotoxicity and establishes a transformation platform for functional genomic studies in Prunus.

Indoleacetic Acids↗
PubMed2001

Characterization and expression of beta-1,3-glucanase genes in peach.

Beta-1,3-glucanase is one of the pathogenesis-related (PR) proteins involved in plant defense responses. A peach beta-1,3-glucanase gene, designated PpGns1, has been isolated and characterized. The deduced amino acid sequence of the product of PpGns indicates that it is a basic isoform (pI 9.8), and contains a putative signal peptide of 38 amino acids but has no C-terminal extension. Amino acid sequence comparisons revealed that PpGns1 is 69% and 67% identical to citrus and soybean beta-1,3-glucanases, respectively. Southern analysis of total genomic DNA also indicates that at least three genes for beta-1,3-glucanases exist in peach, forming a small gene family. Characterization of four additional clones by PCR has identified a second beta-1,3-glucanase gene, PpGns2. PpGns2 has been partially sequenced, and when compared to PpGns1, it shows high sequence homology, 96% and 99% nucleotide identity in the first and (partial) second exons, respectively. The deduced partial sequence of the PpGns2 product displays only two differences from PpGns1 in the signal peptide and one in the (partial) mature protein (141 amino acids). The 5'-flanking promoter regions of these two genes share 90% identity in nucleotide sequences interrupted by five major gaps (4-109 nt long). The promoter region contains various sequences similar to cis-regulatory elements present in different stress-induced plant genes. In leaves and stems of peach shoot cultures grown in vitro, PpGns1 is induced within 12 h after exposure to a culture filtrate of Xanthomonas campestris pv. pruni or ethephon. However, it is not induced following treatment with mercuric chloride.

Amino Acid Sequence↗
PubMed2001

Study of the polymerization step of the rolling circle replication of peach latent mosaic viroid.

We have developed an in vitro transcriptional assay using Escherichia coli RNA polymerase to initiate the replication of peach latent mosaic viroid (PLMVd). Regardless of the polarity of the PLMVd strand used as template, initiation in vitro occurred at the same hairpin structure. These initiation sites correspond to the 5'-ends of two small (280 nt) PLMVd-related RNAs found in infected peach leaves. Using a series of truncated PLMVd-derived transcripts, we have demonstrated that the viroid domain composed solely of the self-complementary hammerhead sequences is sufficient to trigger polymerase-driven replication in vitro. These data suggest that the bacterial-like RNA polymerase from peach chloroplasts catalyzes PLMVd replication.

Base Sequence↗
PubMed2006

Activity and subcellular localization of glucose-6-phosphate dehydrogenase in peach fruits.

The subcellular distribution and activity of glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) were studied in developing peach (Prunus persica L. Batsch cv. Zaoyu) fruit. Fruit tissues were separated by differential centrifugation at 15,000g into plastidic and cytosolic fractions. There was no serious loss of enzyme activity (or activation) during the preparation of fractions. G6PDH activity was found in both the plastidic and cytosolic compartments. Moreover, DTT had no effect on the plastidic G6PDH activities, that is, the redox regulatory mechanism did not play an important role in the peach fleshy tissue. Results from the immunogold electron-microscope localization revealed that G6PDH isoenzymes were mainly present in the cytosol, the secondary wall and plastids (chloroplasts and chromoplasts), but scarcely found in the starch granules or the cell wall. In addition to a decrease in fruit firmness, the G6PDH activity in the cytotolic and plastidic fractions increased, and anthocyanin started to accumulate during fruit maturation. These results suggest that G6PDH, by providing precursors for metabolic processes, might be associated with the red coloration that occurs in peach fruit.

Anthocyanins↗
PubMed2005

Detection of uronic oxidase activity in ripening peaches.

Uronic acid oxidase activity was found in an extract from harvested peaches that was incubated with citrus pectin at pH 8.5. The product of this reaction was identified by GC-MS analysis to be galactaric acid. The reaction was linear at 37 degrees C for up to 20 h, and the pH optimum was 8.5. The activity found in firm peaches one day after harvest did not change as the peaches softened over 5 days to eating softness. The incubation conditions were those suitable for monitoring the activity of pectate lyase, but instead of finding an increase in galacturonosyl residue reducing groups due to generation of pectin-derived oligosaccharides, uronic acid oxidase catalyzed the oxidation of the aldehyde reducing functions to carboxyl groups.

Aldehydes↗
PubMed2005

Peach: a simple Perl-based system for distributed computation and its application to cryo-EM data processing.

A simple distributed processing system named "Peach" was developed to meet the rising computational demands of modern structural biology (and other) laboratories without additional expense by using existing hardware resources more efficiently. A central server distributes jobs to idle workstations in such a way that each computer is used maximally, but without disturbing intermittent interactive users. As compared to other distributed systems, Peach is simple, easy to install, easy to administer, easy to use, scalable, and robust. While it was designed to queue and distribute large numbers of small tasks to participating computers, it can also be used to send single jobs automatically to the fastest currently available computer and/or survey the activity of an entire laboratory's computers. Tests of robustness and scalability are reported, as are three specific electron cryomicroscopy applications where Peach enabled projects that would not otherwise have been feasible without an expensive, dedicated cluster.

Computational Biology↗
PubMed2001

Proteolytic activation of latent Paraguaya peach PPO. Characterization of monophenolase activity.

The kinetics of the activation process of latent peach PPO by trypsin was studied. By coupling this activation process to the oxidation of 4-tert-butylcatechol (TBC) to its corresponding quinone, it was possible to evaluate the specific rate constant of active PPO formation, k(3), which showed a value of 0.04 s(-1). This proteolytic activation of latent peach PPO permitted us to characterize the monophenolase activity of peach PPO for the first time using p-cresol as substrate, and it showed the characteristic lag period of the kinetic mechanism of monophenols hydroxylation, which depended on the enzyme and substrate concentration, the pH and the presence of catalytic amounts of o-diphenol (4-methylcatechol). The enzyme activation constant, k(act), was 2 microM.

Catechol Oxidase↗