Prunus Persica Cv Research Articles

Processing browning and increasing multiplication and rotting of Peach rootstock cv. Garnem by using antioxidants and plant growth regulators in vitro

The study aimed to find an accurate propagation program for the rootstock of peach Prunus persica cv. Garnem. The apical shoots and nodes of this rootstock were used as explants for the stages of initiation and multiplication, and they were planted on MS medium after adding different concentrations of Active Charcoal (AC), Polyvinyl Pyrrolidone (PVP), and Benzyl adenine (BA). The shoots were planted for the purpose of rooting on MS medium containing different concentrations of salts (1/4 MS, 1/2 MS and full MS salts) with different concentrations of IBA. In the establishment phase, the apical shoots grown on medium supplied with AC were given the highest response rate, the highest average length of plantlet, and the highest number of leaves. The best multiplication of explants in terms of the number of shoots and their length were obtained when cultivated on a medium supplemented with BA at 1 and 2 mg.L-1, whereas the application of BA at 1 mg. L-1 to the cultivated nodes gave the highest number of leaves. The best rooting percent was obtained when plantlets were s treated with 2 mg. L-1 was applied to 1/4 MS medium. The highest number of roots was obtained from plantlets grown in 1/2 MS medium treated with IBA at 3 mg.L-1, whereas the longest root was obtained from plantlets grown in 1/2 MS medium treated with 1 mg.L-1IBA.

Near-Freezing Temperature Storage Improves Peach Fruit Chilling Tolerance by Regulating the Antioxidant and Proline Metabolism

Chilling injury (CI) in peach fruit (Prunus persica cv. Yuhualu) is generally caused by long-time low temperature (5 °C or 0 °C) storage. However, peach fruit stored at near-freezing temperature (NFT in this research is −1 °C), defined as within 0.5 °C above the biological freezing point of biological tissue, does not exhibit CI symptoms. The effect of NFT on the CI, proline metabolism, and antioxidant capability of peach fruit during storage was studied and compared with 5 °C and 0 °C storage as controls. The results exhibit that NFT completely inhibited the occurrence of CI in peach fruit. NFT significantly (p < 0.05) enhanced the activities of superoxide dismutase, catalase, ascorbate peroxidase, and 1,1-diphenyl-2-picrylhydrazyl scavenging capacity. Moreover, the increase of malondialdehyde, ion leakage, and H2O2 accumulation were inhibited remarkably by NFT, and decreases in the contents of phenolics and ascorbic acid were slowed significantly in peach fruit stored at NFT (p < 0.05). Additionally, NFT storage enhanced proline accumulation by modulating the activity of proline metabolizing enzymes. In conclusion, the above results suggest that NFT storage can improve the chilling tolerance of peach fruit by regulating the antioxidant defense and proline metabolism, which might represent a potential novel method to store fruits and vegetables for longer storage times.

Vegetative growth, yield, and water productivity of an early maturing peach cultivar under deficit irrigation strategies in a warm and arid area

AbstractDeficit irrigation strategies are considered as promising irrigation management for water saving. In the arid areas of southern Tunisia, agriculture relies heavily on irrigation. With rainfall scarcity, valuable management of water requires efficient approaches. In this context, the effects of deficit irrigation (CDI) and partial root zone drying (PRD) on the vegetative and fruiting behaviour of an early maturing peach (Prunus persica cv. Flordastar) were investigated. Shoot and trunk growth, yield, and fruit size were evaluated during three successive years (2013–2015). In reference to full irrigation (FI) treatment, a 50% water restriction was applied using CDI and PRD. The results obtained showed that both strategies at 50% crop evapotranspiration induced a similar significant reduction of tree vigour mediated by shoot length, trunk cross‐sectional area, and pruning wood weight. Consequently, there was a significant yield loss of 25% following the continuous water restriction of 50% observed throughout the experimental period. However, these yield losses were offset by substantial water savings in the range of 48%–52% and a significant increase of agricultural water productivity. Hence, these techniques lead to significant water savings and vegetative and yield losses offset by a significant increase in water productivity.

Viral Reservoir Capacity of Wild Prunus Alternative Hosts of Plum Pox Virus Through Multiple Cycles of Transmission and Dormancy.

Plum pox virus (PPV) is a significant pathogen of Prunus worldwide and is known for having a broad experimental host range. Many of these hosts represent epidemiological risks as potential wild viral reservoirs. A comparative study of the PPV reservoir capacity of three commonly found native North American species, western choke cherry (Prunus virginiana var. demissa), black cherry (Prunus serotina), and American plum (Prunus americana) was conducted. Pennsylvania isolates of PPV-D were transmitted from the original host peach (Prunus persica cv. GF305) to all three species. Viral accumulation and transmission rates to alternative hosts and peach were monitored over the course of five vegetative growth and cold induced dormancy (CID) cycles. The three alternative host species demonstrated differences in their ability to maintain PPV-D and the likelihood of transmission to additional alternative hosts or back transmission to peach. Western choke cherry had low (5.8%) initial infection levels, PPV-D was not transmissible to additional western choke cherry, and transmission of PPV-D from western choke cherry to peach was only possible before the first CID cycle. Black cherry had intermediate initial infection levels (26.6%) but did not maintain high infection levels after repeated CID cycles. Conversely, American plum had a high level (50%) of initial infection that was not significantly different from initial infection in peach (72.2%) and maintained moderate levels (15 to 25%) of infection and PPV-D transmission to both American plum and peach through all five cycles of CID. Our results indicate that American plum has the greatest potential to act as a reservoir host for Pennsylvania isolates of PPV-D.

Cultivar and tissue-specific changes of abscisic acid, its catabolites and individual sugars during postharvest handling of flat peaches (Prunus persica cv. platycarpa)

The role of abscisic acid (ABA) during postharvest ripening of peaches remains unclear. This study aimed to investigate the temporal and tissue-specific changes in ABA, and ABA catabolites, of two flat peach cultivars, ‘Plane Sun’ and ‘Platibell’, during the stone fruit supply chain. The relationship between ABA catabolism, ethylene production, individual sugar changes and fruit firmness was also studied. We found that flat peaches can produce and metabolise ABA during postharvest ripening, and that this is cultivar and tissue dependent. Our results demonstrated that a burst in ABA concentration preceded that of ethylene production in ‘Plane Sun’ fruit, suggesting cross-talk between the two hormones. ABA and ethylene were both negatively correlated with fruit firmness, whilst sugar content, especially glucose, was only correlated with ABA. In conclusion, ABA may trigger ethylene production changes while also affecting sugar metabolism leading to fruit softening and over-ripening associated processes during stone fruit postharvest handling.

Metagenomic Survey of the Highly Polyphagous Anastrepha ludens Developing in Ancestral and Exotic Hosts Reveals the Lack of a Stable Microbiota in Larvae and the Strong Influence of Metamorphosis on Adult Gut Microbiota.

We studied the microbiota of a highly polyphagous insect, Anastrepha ludens (Diptera: Tephritidae), developing in six of its hosts, including two ancestral (Casimiroa edulis and C. greggii), three exotic (Mangifera indica cv. Ataulfo, Prunus persica cv. Criollo, and Citrus x aurantium) and one occasional host (Capsicum pubescens cv. Manzano), that is only used when extreme drought conditions limit fruiting by the common hosts. One of the exotic hosts (“criollo” peach) is rife with polyphenols and the occasional host with capsaicinoids exerting high fitness costs on the larvae. We pursued the following questions: (1) How is the microbial composition of the larval food related to the composition of the larval and adult microbiota, and what does this tell us about transience and stability of this species’ gut microbiota? (2) How does metamorphosis affect the adult microbiota? We surveyed the microbiota of the pulp of each host fruit, as well as the gut microbiota of larvae and adult flies and found that the gut of A. ludens larvae lacks a stable microbiota, since it was invariably associated with the composition of the pulp microbiota of the host plant species studied and was also different from the microbiota of adult flies indicating that metamorphosis filters out much of the microbiota present in larvae. The microbiota of adult males and females was similar between them, independent of host plant and was dominated by bacteria within the Enterobacteriaceae. We found that in the case of the “toxic” occasional host C. pubescens the microbiota is enriched in potentially deleterious genera that were much less abundant in the other hosts. In contrast, the pulp of the ancestral host C. edulis is enriched in several bacterial groups that can be beneficial for larval development. We also report for the first time the presence of bacteria within the Arcobacteraceae family in the gut microbiota of A. ludens stemming from C. edulis. Based on our findings, we conclude that changes in the food-associated microbiota dictate major changes in the larval microbiota, suggesting that most larval gut microbiota is originated from the food.

Response of rooting media on sprouting propagation through cuttings in peach (Prunus persica) cv. Shan-i-Punjab

Response of rooting media on sprouting propagation through cuttings in peach (Prunus persica) cv. Shan-i-Punjab

First Report of Ceratocystis changhui Causing Postharvest Fruit Rot of Peach in Kunming, China.

The peach (Prunus persica (L) Batsch) is a predominant commercially grown stone fruit in China (Lee et al. 1990). Ceratocystis changhui is an aggressive pathogen causing typical black rot symptoms on corms of taro (Colocasia esculenta) (Liu et al. 2018), it has not been reported on other hosts. During the summer and autumn of 2013, a postharvest fruit rot disease was observed on several peaches at a farmer's market (N 25°02'; E 102°42') in Kunming City, Yunnan Province, China. The incidence of the disease varied from 5 to 20%. Necrotic spots were first observed on the infected peach fruit (Prunus persica cv. shuimitao). The spots enlarged gradually and developed into a brown, water-soaked and rotted lesion. Eventually, the whole fruit became soft, rotted and covered with a gray-brown mycelium (Fig. 1 A, B). The isolates were obtained from the symptomatic tissues incubated on slices of fresh carrot root (Moller et al. 1968). After 5 to 10 days of incubation, perithecia and mycelium were observed growing on carrot slices. Spore masses were removed from the apices of perithecia, transferred to potato dextrose agar medium (PDA) and incubated at 25°C for 5 to 10 days, followed by single-spore isolation. All eight single-spore isolates from peach fruits obtained in this study were deposited in the State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan Agricultural University, China. In culture, mycelium was initially white, gradually turned to greyish-green or brown (Fig. 1E, F). Measurements were made 7 days after the formation of perithecia. Perithecia (Fig. 1G) were black, globose, 185.71 to 305.56 μm × 142.86 to 264.29 µm and showed a long black neck, 600 to 957.14 µm (Fig. 1H). Ascospores (Fig. 1I) were helmet-hat shaped and 2.86 to 6.67 µm ×3.81 to 4.76 µm. Cylindrical conidia (Fig. 1J) 6.67 to 38. 95 µm × 2.86 to7.62 µm were observed. Chlamydospore (Fig. 1K), 8.57 to 13.33 μm × 5.71 to 9.52 μm, were ovoid or obpyriform, smooth. To further verify pathogen identity the internal transcribed spacer (ITS) region of rDNA was amplified using primers ITS1F and ITS4 (Thorpe et al. 2005), and the total genomic DNA from the mycelia of five isolates was extracted using a CTAB method (Lee &Taylor 1990). The nucleotide sequences have been blasted and deposited in the GenBank database. Analysis of the ITS sequences from the isolates T1-1yp, T1-2yp, T2-1yp (GenBank accession no. KY580895-KY580897) showed 99% to 100% similarity with isolates C. changhui CMW43272 (KY643886), CMW43281 (KY643884), CMW46112 (KY643891) and CMW46113 (KY643892) from taro in China. Phylogenetic trees based on the maximum-likelihood (ML) method were constructed using MEGA 7. ITS sequences of other Ceratocystis spp. were attained from NCBI for comparative analysis (Liu et al. 2018), and Davidsoniella virescens (CMW11164) served as outgroup. The robustness of ML tree was evaluated with 1,000 bootstrap (BS) values. The pathogen was identified as C. changhui based on the phylogenetic analysis (Fig. 2). Three isolates (T1-1yp, T1-2yp, T2-1yp) were used for pathogenicity. Nine Prunus persica cv. yingzuitao fruits at early maturity (8 points out of 10) were wound inoculated with 200μL conidia suspension of the fungus (approximately 2.0 × 106 conidia / mL). Degreasing cotton dipped in sterile water was used to raise the humidity in preservation boxes. Boxes were incubated for 10 days at 25°C. Three peaches as controls were treated only with sterile distilled water in the same way. Symptoms of sunken lesions and fruit rot were observed two days after inoculation, and measured at 1.8 to 3.2 cm from the inoculation point within 5 days (Fig. 1C: right, D). The same pathogen was re-isolated from them confirming Koch's postulates. Control peaches remained symptomless. This fungus was morphologically and phylogenetically identified as C. changhui. To our knowledge, this is the first report of C. changhui on postharvest peach in Yunnan, China. The disease will affect quality and taste of peach, so it is critical to deploy appropriate management strategies to limit the fungus spread.

Inoculation of in vitro cultures with rhizosphere microorganisms improve plant development and acclimatization during immature embryo rescue in nectarine and pear breeding programs

In the present study, two fungi Cladosporium ramotenellum strain PGP02 and Phoma spp. strain PGP03 and the bacterium Pseudomonas oryzihabitans PGP01 were isolated from Pyrus and Prunus in vitro rescued embryos, whose plantlets showed a better growth than non-contaminated cultures. Upon identification, concentrated solutions of the three microorganisms were applied to pear (Pyrus communis L.) in vitro rooted plantlets, increasing in different ways biometric parameters such as plant fresh weight (FW), stem length and root length. Then, these microorganisms were tested in embryos derived from three directed crosses between early ripening nectarine varieties (Prunus persica cv. Nectarina). In a first cross, in vitro cultured embryos were inoculated with both fungi, C. ramotenellum PGP02 and Phoma spp. PGP03, at 2 × 107 esp mL−1, and the bacterium P. oryzihabitans PGP01, at 2 × 108 CFU mL−1. In the following crosses, only the bacterium P. oryzihabitans PGP01, at 2 × 108 CFU mL−1, was employed. The effects on number of germinated embryos, development of the subsequent plants, after 24 weeks of in vitro culture, as well as their ex vitro acclimatization performance were analysed. These microorganisms had no effect on the germination efficiency of nectarine embryos. However, the presence of the bacterium P. oryzihabitans PGP01 modified root system architecture in the three crosses, increasing root volume and thickness, which in consequence enhanced the acclimatization efficiency to soil in those crosses with poor acclimation efficiencies. These results enforce a breakthrough in the use of microorganisms along the in vitro embryo rescue used in early ripening peaches and nectarines breeding programmes, and the production of plants more resistant to the stressful conditions imposed by the acclimatization to soil.

Assessing ranked set sampling and ancillary data to improve fruit load estimates in peach orchards

Fruit load estimation at plot level before harvest is a key issue in fruit growing. To face this challenge, two sampling methods to estimate fruit load in a peach tree orchard were compared: simple random sampling (SRS) and ranked set sampling (RSS). The study was carried out in a peach orchard (Prunus persica cv. ‘Platycarpa’) covering a total area of 2.24 ha. Having previously sampled the plot systematically to cover the entire area (104 individual trees or sampling points), both sampling methods (SRS and RSS) were tested by taking samples from this population with varying sample sizes from N = 4 to N = 12. Since RSS requires ancillary information to obtain the samples (ranking mechanism), several proximal and remote sensors already used or recently introduced in agriculture were assessed as data sources. A total of 14 variables provided by 5 different sensors and platforms were considered as potential ancillary variables. Among them, RGB images captured by an unmanned aerial vehicle (UAV), and used to estimate the canopy projected area of individual trees, proved to be the best of the options. This was shown by the high correlation (R = 0.85) between this area and the fruit load, providing RSS with the UAV-based canopy projected area the lowest Coefficient of Error (CE) for a given tree sample size. Then, comparing relative efficiency between random sampling (SRS) and RSS, the latter enables more precise fruit load estimates for any of the considered sample sizes. Interest and opportunity of RSS can be raised from two points of view. In terms of confidence, RSS managed to reduce the variance of fruit load estimates by about half compared to SRS. Sampling errors above the 10% threshold were always produced significantly fewer times using RSS, regardless of the sample size. In terms of operation within the plot, sample size could be reduced by 50%, from N = 10 for SRS to N = 5 for RSS, and this being expected sampling errors less than 10% in practically 70% of the samplings performed in both cases. In summary, fruit growers can take advantage of the combined use of appropriate data (RGB images from UAV) and RSS to optimize sample sizes and operational sampling costs in fruit growing.

Effects of IAA and ABA on the Immature Peach Fruit Development Process

Peach (Prunus persica cv. Dajiubao) was chosen as a model to clarify the roles of IAA and ABA during the fruit ripening process. Seventy days after flowering (DAF), the fruits were treated with IAA and ABA (0.1 mmol·L−1 and 1 mmol·L−1, respectively) and with the IAA transporter inhibitor (NPA) and the ABA biosynthesis inhibitor (NDGA). IAA decreased the fruit ABA concentration, and increased ethylene concentration, leading to fruit (70 DAF) softening and coloration. NPA had the opposite effect. ABA decreased IAA and ethylene concentrations, leading to fruit hardness and lack of color. NDGA had similar effects as with IAA application. A qPCR analysis indicated that in immature fruits, the expression levels of ethylene biosynthesis and signaling genes (PpACS, PpACO, PpETR, PpERF2), anthocyanin biosynthesis genes (PpCHS, PpDFR, PpF3H, PpUFGT), cell wall softening genes (PpEXP1, PpEXP2, PpPG2, PpPME), and auxin biosynthesis genes (PpPIN, PpTIR1) were upregulated by IAA application but were inhibited by NPA. In contrast, these ripening-related genes were downregulated by ABA application, but upregulated by NDGA. Generally, the immature fruit ripening process requires a high IAA concentration to generate a large amount of ethylene. ABA appeared to modulate ripening through interference not only with ethylene and cell wall related genes but also with auxin-related genes.

Comparative “phenol-omics” and gene expression analyses in peach (Prunus persica) skin in response to different postharvest UV-B treatments

Ultraviolet-B (UVB) radiation impacts the plant behaviour in many ways, including modifying their secondary metabolism. Although several studies have quantified the UV-B effects on phenolic composition, most of them focused on leaves or investigated a limited amount of phenolics. The present work aimed to investigate the phenolic changes after two postharvest UV-B treatments, 10 and 60 min (1.39 kJ m−2 and 8.33 kJ m−2, respectively), on peach (Prunus persica cv Fairtime) fruit with a non-targeted, whole profiling approach, and targeted gene expression analysis on skin. After both UV-B exposures, peach fruit were harvested at 24 and 36 h for “phenol-omics” analysis, while additional 6 h and 12 h recovery times were used for gene expression analysis. Our results revealed that both UV-B exposures resulted in a decrease of several phenolic compounds, such as anthocyanins, after 24 h from the exposure. In contrast, the expression of the UV-B signalling components, the phenylpropanoid biosynthesis genes and their transcriptional regulators increased 6 h after the treatment, mostly with a UV-B-dose dependent behaviour, preceding an accumulation of most phenolics in both the UV-B treatments at 36 h compared to 24 h. Orthogonal projections to latent structures discriminant analysis (OPLS-DA) revealed that flavonoids, particularly anthocyanins, were the main phenolic subclasses accumulated after UV-B exposure.

Extension of the Postharvest Life of Nectarine Using Modified Atmosphere Packaging and Potassium Permanganate Treatment

The effects of combinations of modified atmosphere packaging (MAP) with potassium permanganate (KMnO4) based ethylene scrubbers on the storage life and fruit quality of nectarine (Prunus persica cv. Bayramiç Beyazı) were investigated. Three different types of ethylene sachets (contained 3, 7 and 10 g KMnO4) were used and placed beside fruits in polypropylene baskets then lined with MAP. Fruits were stored at 0-1°C and 90% relative humidity throughout 40 day. During the cooling storage period, O2 and CO2 percentage in MAP, fruit firmness, total soluble solids, titratable acidity, ascorbic acid, total flavonoid content, total phenolic content, total antioxidant content and chilling injury (CI) were determined at 10 day interval. KMnO4 treated fruits had shown delayed ripening, reduced respiration and retained of higher firmness. As the dose of KMnO4 treatment increased, it was determined more positive effect on fruit quality. 10 g KMnO4 treatment was most effective in the retention of higher biochemical compounds and inhibition of CI symptoms. The results indicate that KMnO4 treatment, as well as MAP application, should be highly recommended for retaining the fruit quality of cold-stored ‘Bayramiç Beyazı‘ nectarines and fruits treated with 10 g doses of KMnO4 could be stored for 40 days with good quality.

Protein changes in response to photoperiod during dormancy induction in peach leaves and flower buds

Abstract Bud dormancy in deciduous fruit trees is a key feature for the survival of winter chill but is a limiting factor for forcing cultivation in the greenhouse. Photoperiod is an important signal in dormancy induction; the quality and quantity of many genes and proteins can change and undergo a transition from active growth to dormancy. The aim of this work was to provide new insights into these changes during the early stage of dormancy. We analyzed protein changes in response to photoperiod during dormancy induction in peach (Prunus persica cv. Chunjie) leaves and flower buds. The results showed that short photoperiod could get the buds into dormant-induction period under non-low temperature conditions. However, the dormancy induction factor for long photoperiod treatment was the decreasing of the temperature. Sixty-five differentially expressed proteins were revealed, 42 of which were identified. The critical expression period of the differentially expressed proteins was mid-September in the leaves and mid-October or slightly earlier in the flower buds. Compared with that of the other identified proteins, the expression of proteins associated with stimulus responses and stress defense was higher and occurred earlier in short-photoperiod dormancy induction, whereas the expression of proteins associated with photosynthesis and growth was lower. This study is the first to identify the name, expression pattern, functional category, and biological function of various proteins in peach leaves and flower buds during photoperiod dormancy induction.

Diversity of Xylella fastidiosa host suitability among siblings from a non-traditional interspecific Prunus cross

Ten F2 clones from an initial hybridization of Prunus webbii × Prunus persica cv Harrow Blood were evaluated under greenhouse conditions for their reaction to Xylella fastidiosa subsp. fastidiosa strain M23 during two growing seasons. Clonal accessions used for the study were selected on the basis of horticultural diversity, and were a small subset of trees from a large F2 population. Foliar symptoms of M23-inoculated trees were monitored weekly throughout the 20-week growth period. Clones were then sampled for bacterial titer determinations. With the exception of parental accession Harrow Blood, all clones yielded measurable titer; however, almond leaf scorch disease symptoms were never observed in five of the ten sibling clonal accessions. Vegetative bud break and bloom phenology data collected from field-grown mother trees over a 7 year period as well as leaf morphology characters of the clonal accessions were examined for associations with bacterial titers of inoculated clones using a principal components analysis. No clear associations were noted, with small sample size limiting the predictive ability of the analysis.

Multiplex analyses of the changes of aromatic compounds during the development of peach fruit using GC–MS and iTRAQ proteomic techniques

Abstract This study aimed to combine GC–MS and iTRAQ techniques to investigate the changes in aromatic compounds and protein profiles of peach fruit peel (Prunus persica cv. Hujiingmilu) at its different developmental stages. The fruits were collected 50, 90, 95, 100, and 105 days after flowering. GC–MS during development and ripening revealed more than 200 volatile compounds, and 18 of them were aroma-related. Based on the varying amount and pattern, γ-decalactone, δ-decalactone, hexyl acetate, and 1-hexanol were involved in peach aroma. Proteomic analysis with the iTRAQ technique identified 1848 unique proteins, out of which 842 were related to biological processes and 100 related with aromatic compounds and energy transfer during fruit development and ripening. The up-regulated linoleate 9(S)-lipoxygenase plays an important role in the increase of hexanal and benzaldehyde content during ripening. The activity of phosphoglycerate mutase, glyceraldehyde 3-phosphate dehydrogenase, and inorganic pyrophosphatase regulated the terpenoids production for linalool through the 3-phosphoglyceric acid/pyruvic acid pathway but not the mevalonic acid pathway. Caffeoyl-CoA-O-methyltransferase had linear interactions with 4-coumarate-CoA ligase and 3-hydroxyisobutyryl-CoA hydrolase, and it might be the critical pathway of aromatic compounds during the development of peach fruit. Overall, the fatty acid metabolism was the primary pathway for aromatic compound formation in peach fruit and the AOC, AOS, LOX, and OPR were the key functional proteins for the formation of lactones and esters representing the characteristic aroma of honey peach. This study combined the techniques of GC–MS and proteomics to delineate the relationship between the change of aromatic compounds and proteins and their possible biological processes with aroma formation in peach fruit during development and ripening.

Determination of Quality Changes in Peaches Wrapped in Active Paper and Stored at Ambient Temperature in Summer

Peaches are known for their palatable flavor and abundant nutrients. However, peaches are perishable, and the existing preservation techniques for peaches are still immature. To further extend the shelf life and prevent nutrient loss of perishable peaches under ambient temperature in summer (approximately 25–32 °C), we conducted experiments wrapping peaches (Prunus persica cv ‘Baihua’) in single- and composite-treated vegetal fibrous papers that contained calcium carbonate, phytic acid, Na-alginate and vitamin C. The pathogenic fungi that primarily caused peach decay during storage belonged to the genera of Penicillium, Botrytis, Aspergillus, Alternaria, and Rhizopus. After analyzing quality attributes, including weight loss, firmness, soluble sugar content, respiration rate, relative electric conductivity, malonaldehyde content, peroxidase activity and the decay index, we proved that vitamin C within the preservative paper greatly contributes to peach preservation. Combined with phytic acid and Na-alginate, the composite vitamin C preservative papers played significant roles in delaying fruit senescence, and 0.4% (w/v) vitamin C preservative paper with 1% Na-alginate could maintain quality and extend shelf life with the best effect. This preservation technique significantly postponed the respiration peak by 2–3 days and is a significant contribution to contemporary commercial production.

Quantitative proteomic analysis of pre- and post-harvest peach fruit ripening based on iTRAQ technique

To further elucidate the molecular mechanism involved in peach (Prunus persica cv. Xiacui) fruit ripening, a differential proteomic analysis was conducted using iTRAQ based strategy for studying peach fruit ripening from day 15 before commercial harvesting (D0) to 15-day storage period at 25 °C. 64 differentially expressed proteins (≥1.5-fold, p ≤ 0.05) were successfully identified. Lipoxygenase (LOX) family members exposed the status of causing disorder metabolism and senescence by increased expressions. Some well-known antioxidant enzymes did not show significant expressions especially in later storage time. Nevertheless, proteins involved in ABA metabolism were up-regulated, demonstrating the important role of ABA in adaptation of plants to various environmental stresses. Glutathione S-transferase, cysteine proteinase inhibitor, transcription factor bHLH135 all showed great potential in response to ROS or other stresses. Proteins associated with flavonoid biosynthesis and amino acid metabolism also revealed critical roles in metabolism during storage.

Micropropagation of Peach, Prunus persica (L.) BATSCH. cv. Garnem

The present study aimed to develop micropropagation procedure for Prunus persica cv. Garnem. Shoot induction and multiplication was found from nodal explants cultured on MS medium fortified with different concentrations of two cytokinins (6-benzyladeninepourine and Kinetin) alone and in combination with 0.5 mg/l gibberellic acid and 0.01 mg/l indole-3-butyric acid. Microplantlets were cultured to root on ½ strength MS medium supplemented with different concentrations of indole-3-butyric acid and α-naphthalene-acetic acid alone. 6-Benzyladeninepourine (0.5 mg/l) with indole-3-butyric acid (0.01 mg/l) and gibberellic acid (0.5 mg/l) was found to be the optimum combination treatment for shoot initiation (100%). 6-Benzyladeninepourine (2.0 mg/l) with indole-3-butyric acid (0.01 mg/l) and gibberellic acid (0.5 mg/l) was found to be optimum for maximum shoot number per explant (7.67). The maximum rooting (42.86%), maximum root number/shoot (6.33) and longest rooting (7.17 cm) were found at 1.5 mg/l indole-3-butyric acid. α-naphthalene-acetic acid was found to be not effective. The plantlets were acclimatized in the glasshouse and survival percentage was 73.3% at potting mixture of autoclaved river sand, forest soil and manure in a 2:1:1 (v/v/v) ratio. Key words: Acclimatization, auxin, cytokinin, micropropagation, Prunus persica.

High-Throughput Sequencing Identifies Novel Viruses in Nectarine: Insights to the Etiology of Stem-Pitting Disease

Recent studies have shown the superiority of high-throughput sequencing (HTS) technology over many standard protocols for pathogen detection. HTS was initiated on fruit tree accessions from disparate sources to improve and advance virus-testing procedures. A virus with genomic features resembling most closely that of the recently described Nectarine stem-pitting-associated virus, putative member of genus Luteovirus, was found in three nectarine trees (Prunus persica cv. nectarina), each exhibiting stem-pitting symptoms on the woody cylinder above the graft union. In these samples, HTS also revealed the presence of a coinfecting virus with genome characteristics typical of members of the genus Marafivirus. The same marafivirus- and luteovirus-like viruses were detected in nonsymptomatic nectarine and peach selections, indicating only a loose relationship between these two viruses with nectarine stem-pitting disease symptoms. Two selections infected with each of these viruses had previously tested free of known virus or virus-like agents using the current biological, serological, and molecular tests employed at the Clean Plant Center Northwest. Overall, this study presents the characterization by HTS of novel marafivirus- and luteovirus-like viruses of nectarine, and provides further insights into the etiology of nectarine stem-pitting disease. The discovery of these new viruses emphasizes the ability of HTS to reveal viruses that are not detected by existing protocols.