Search Results (39)

Pseudomonas syringae pv. syringae (Pss) is the causal agent of bacterial canker, a disease that can result in yield losses, aerial tissue damage, and tree mortality in stone fruits worldwide. Peach, one of the major stone fruit crops, experiences significant yield losses and tree mortality attributed to bacterial canker in the United States. As the second-largest peach-producing state, South Carolina faces direct and significant impacts due to Pss. Early evaluations of peach scion responses to Pss infection have relied primarily on circumstantial field observations in rootstock trials. Although laboratory evaluations in peach have been reported, these studies primarily focused on pathogen virulence testing or small accession sets and did not establish a standardized, scalable detached twig protocol for systematic germplasm phenotyping. The absence of a clearly described laboratory assay has limited reproducible and large-scale evaluation of bacterial canker tolerance in peach. To address this gap, a detached dormant twig assay, previously developed for cherry, was adapted and optimized for peach. Dormant shoots from nine peach accessions were cut into 10 cm segments, surface-sterilized, and inoculated with a Pss suspension prepared in 10 mM MgCl₂ buffer or with the buffer alone. After six weeks of incubation, inner bark lesion size was evaluated visually and quantified using ImageJ. A newly developed visual rating scale was established and compared with quantitative lesion measurements. Spearman correlation analysis showed strong positive correlations between visual disease scores and ImageJ-based lesion measurements across two independent replicates (ρ = 0.80–1.00, p < 0.01), while shoot segment diameter showed weak-to-moderate negative correlations with disease severity. This adapted and consolidated dormant twig assay provides a practical, reproducible, and scalable method for phenotyping bacterial canker tolerance in peach and supports future germplasm screening and breeding efforts. Full article

Adventitious shoot regeneration is an essential prerequisite for the application of biotechnological tools such as CRISPR-Cas in woody fruit crops. Nonetheless, many Prunus species exhibit strong recalcitrance to in vitro regeneration. Light quality has emerged as an important environmental factor influencing morphogenic responses under in vitro conditions. In this study, the effect of different LED light spectra on adventitious shoot regeneration was evaluated in three peach-related genotypes: the commercial peach cultivar ‘Siroco 5’ (Prunus persica L.) and the hybrid rootstocks ‘GF677’ and ‘Garnem’ (P. persica × P. dulcis). Callus explants derived from the basal region of in vitro proliferation cultures were exposed for 30 days to five LED light treatments: white (control), blue, red + far-red, mixed (red + far-red + blue), and sequential LED light. Regeneration efficiency was assessed through the frequency of organogenic callus formation (FOC), the number of regenerated shoots per explant, the organogenic rate, and the fresh weight of the regenerated explants. While FOC was consistently high across genotypes and light treatments, shoot regeneration was significantly influenced by both genotype and light spectrum. The hybrid rootstocks exhibited a higher regeneration capacity than the commercial cultivar under most conditions. Red + far-red LED light promoted the highest regeneration efficiency across all of the genotypes, particularly enhancing shoot regeneration and fresh weight in ‘Siroco 5’. These results demonstrate that LED light spectrum modulation, especially red + far-red, is an effective strategy to optimize adventitious shoot regeneration in peach cultivar and hybrid rootstock genotypes, providing a robust basis for future applications in micropropagation and genetic improvement programs. Full article

Adventitious root (AR) formation is critical for the vegetative propagation of peach rootstocks. While miRNAs are known to regulate AR development, the role of specific miRNAs and target genes in peach rootstocks remains poorly understand. In this study, we profiled the miRNAome of ‘GF677’ peach rootstock during indole-3-butyric acid (IBA)-induced AR formation. Samples were collected at key four time points (2 h, 2, 10, and 17 days) based on the dynamic changes in endogenous auxin and root morphogenesis. A total of 188 miRNAs were identified, including 60 novel miRNAs. There were 28, 45, 59, 18, 30, and 14 differentially expressed miRNAs (DEMs) in the following six comparison groups of libraries: 2 h vs. 2 d, 2 h vs. 10 d, 2 h vs. 17 d, 2 d vs. 10 d, 2 d vs. 17 d, and 10 d vs. 17 d, respectively. KEGG pathway enrichment indicated that the target genes of DEMs were predominantly associated with signal transduction and metabolism. Specifically, the plant hormone signaling and starch and sucrose metabolism pathways were enriched across all the six comparison groups, while each group exhibited a unique enriched pathway. Additionally, the functional validation of miR319, a DEM, through transgenic analysis in Arabidopsis revealed its regulatory role in AR development. Collectively, this study provides the first insights into the role of miRNAs in peach adventitious rooting, laying a theoretical foundation for improving the vegetative propagation of peach rootstock. Full article

Fruit tree rootstock breeding is prolonged by extended juvenile phases, high heterozygosity, limited germplasm diversity, and hybrid incompatibilities, often requiring four decades to release new cultivars. Direct somatic embryogenesis (DSE) in established peach rootstocks presents a promising avenue for rapid genetic transformation and breeding. However, peach is highly recalcitrant to in vitro regeneration, posing major challenges for organogenesis and somatic embryogenesis (SE). This study evaluated the effects of 2,4-dichlorophenoxyacetic acid (2,4-D) and Kinetin (KIN) on SE %, SE productivity, and callus % rate in the widely used Guardian^® peach rootstock. A 5 × 3 full factorial completely randomized design was used to test 15 different combinations of 2,4-D and KIN on immature cotyledons, classified as upper or lower based on their position on the preculture medium. Media formulation containing a higher concentration (3.2 µM) of 2,4-D and KIN induced SE in ~50% of lower and ~85% of upper cotyledons. Optimal SE productivity occurred with higher KIN (3.2 µM) and reduced 2,4-D (2.6 µM). Callus formation peaked with 1.8 µM 2,4-D and 3.2 µM KIN. This highly reproducible research establishes a robust whole plant regeneration system via DSE in Guardian^® peach rootstock using immature cotyledons, providing a foundation for expedited trait manipulation through biotechnological approaches. Full article

This study examines how various rootstocks affect the pomological, biochemical, and aroma contents of the local ‘Sırrı’ peach genotype grown in the Lapseki region of Türkiye. The research focused on peach trees grafted onto three distinct rootstocks: ‘Seedling’, ‘GF-677’ (P. persica × P. amygdalus), and ‘Rootpac-R’ (P. cerasifera × P. amygdalus). The results showed that peaches from the ‘Seedling’ and ‘GF-677’ rootstocks had larger sizes, greater weights, and brighter colors compared to those from ‘Rootpac-R’. Furthermore, the rootstocks impacted essential quality factors such as soluble solid content, firmness, fruit–flesh ratio, titratable acidity, and total phenolic content levels. The analysis of volatile compounds indicated that aldehydes (which varied from 67.02% to 63.74%), lactones (which changed from 9.14% to 7.99%), and esters (which changed from 12.51% to 11.92%) were the major aroma types in ‘Sırrı’ peaches, with the ‘GF-677’ rootstock exhibiting amplified fruity and sweet aromas due to increased lactone levels. Principal Component Analysis (PCA) revealed the significant effects of rootstocks on both pomological and biochemical characteristics, with ‘Seedling’ showing elevated biophenol levels and ‘GF-677’ contributing to a firmer texture. These findings underscore the importance of rootstock choice in enhancing fruit quality and aroma, indicating that the ‘Sırrı’ genotype is highly suitable for commercial production and future breeding efforts. Full article

Kiwifruit, with its unique flavor, nutritional value, and economic benefits, has gained significant attention in agriculture production. Kiwifruit plants have traditionally been propagated without grafting, but recently, grafting has become a more common practice. A new and complex disease called Kiwifruit Vine Decline Syndrome (KVDS) has emerged in different kiwifruit-growing areas. The syndrome was first recognized in Italy, although similar symptoms had been observed in New Zealand during the 1990s before subsequently spreading worldwide. While kiwifruit was not initially grafted in commercial orchards, the expansion of cultivation into regions with heavy soils or other challenging environmental conditions may make grafting selected kiwifruit cultivars onto KVDS-resistant or -tolerant rootstocks essential for the future of this crop. Grafting is a common horticultural practice, widely used to propagate several commercially important fruit crops, including kiwifruits, apples, grapes, citrus, peaches, apricots, and vegetables. Grafting methods and genetic compatibility have a crucial impact on fruit quality, yield, environmental adaptability, and disease resistance. Achieving successful compatibility involves a series of steps. During grafting, some scion/rootstock combinations exhibit poor graft compatibility, preventing the formation of a successful graft union. Identifying symptoms of graft incompatibility can be challenging, as they are not always evident in the first year after grafting. The causes of graft incompatibility are still largely unknown, especially in the case of kiwifruit. This review aims to examine the mechanisms of graft compatibility and incompatibility across different fruit crops. This review’s goal is to identify potential markers and techniques that could enhance grafting success and boost the commercial production of kiwifruit. Full article

Sharka disease, caused by the plum pox virus (PPV), negatively impacts stone fruit production, resulting in economic losses. It has been demonstrated that grafting the almond (Prunus dulcis (Miller) D.A. Webb) variety ‘Garrigues’ into susceptible peach (Prunus persica (L.) Batsch) rootstocks can result in PPV resistance. The molecular circuits related to grafting in Prunus species, however, have not been fully investigated. In this study, susceptible peach rootstocks ‘GF305’ were either heterografted with ‘Garrigues’ almond or homografted with the same cultivar. Peach samples were collected at two stages of scion development, with ungrafted plants utilized as controls. Profiles of transcripts, small RNAs (sRNAs), and DNA methylation were obtained and analyzed on a genome-wide scale. Homografting and heterografting significantly altered the transcriptome and methylome of peach rootstocks, with these modifications being more pronounced during the early stages of scion development. The profiles of sRNAs were significantly more impacted when almonds were used as a scion as opposed to peaches, likely due to the transmission of PPV-unrelated viral sequences. Gene expression differences resulting from DNA methylation alterations are more thoroughly documented at the promoter sequences of genes than within their bodies. This study suggests that the ‘Garrigues’ almond variety triggers a complex defense response in the peach rootstock, potentially involving the interplay of epigenetic modifications and small RNA-mediated priming of antiviral defenses, which ultimately may contribute to PPV resistance. Full article

Dwarfing rootstocks enhance planting density, lower tree height, and reduce both labor in peach production. Cerasus humilis is distinguished by its dwarf stature, rapid growth, and robust fruiting capabilities, presenting substantial potential for further development. In this study, Ruipan 4 was used as the scion and grafted onto Amygdalus persica and Cerasus humilis, respectively. The results indicate that compared to grafting combination R/M (Ruipan 4/Amygdalus persica), grafting combination R/O (Ruipan 4/Cerasus humilis) plants show a significant reduction in height and a significant increase in flower buds. RNA-seq indicates that genes related to gibberellin (GA) and auxin metabolism are involved in the dwarfing process of scions mediated by C. humilis. The expression levels of the GA metabolism-related gene PpGA2ox7 significantly increased in R/O and are strongly correlated with plant height, branch length, and internode length. Furthermore, GA levels were significantly reduced in R/O. The transcription factor PpGATA21 was identified through yeast one-hybrid screening of the PpGA2ox7 promoter. Yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) demonstrate that PpGATA21 can bind to the promoter of PpGA2ox7 and activate its expression. Overall, PpGATA21 activates the expression of the GA-related gene PpGA2ox7, resulting in reduced GA levels and consequent dwarfing of plants mediated by C. humilis. This study provides new insights into the mechanisms of C. humilis and offers a scientific foundation for the dwarfing and high-density cultivation of peach trees. Full article

Two peach rootstocks (‘Guardian’ and ‘MP-29’) and ten winter cover crops (rye, wheat, barley, triticale, oat, Austrian winter pea, crimson clover, balansa clover, hairy vetch, and daikon radish) were evaluated in a greenhouse environment to determine their suitability to host ring nematode, Mesocriconema xenoplax. Each crop was inoculated with 500 ring nematodes, and the experiments were terminated 60 days after inoculation. The reproduction factor (ratio of final and initial nematode population) ranged from 0 to 13.8, indicating the crops greatly varied in their host suitability to ring nematode. ‘Guardian’ has been known to tolerate ring nematode; however, results from the current study suggest the tolerance statement is anecdotal. Another peach rootstock, ‘MP-29’, was also a good host for ring nematode, suggesting an urgency to develop ring nematode-resistant peach rootstocks. Wheat supported the least to no nematode reproduction while pea supported the greatest reproduction. The rest of the cover crops were poor to good hosts to ring nematodes. Although planting cover crops in peach orchards is not common, employing non or poor host crops can help suppress nematodes in addition to having soil health benefits. Furthermore, peach breeding programs should focus on finding and introgressing ring nematode resistance in commercial rootstocks. Full article

Peaches and nectarines have a short shelf life even when harvested at appropriate physiological maturity. Market life is increased by storage at low temperatures. However, chilling injury symptoms can appear, causing physiological disorders and limiting shipping potential. The rootstock effect on the post-harvest quality has hardly been explored. Thus, the principal aim of this work was to study the influence of seven different Prunus rootstocks on the “Big Top” nectarine cv, considering harvest and post-harvest quality parameters and their correlation with chilling injury disorders. Basic fruit quality traits, individual sugars and organic acids analyzed by HPLC and other biochemical compounds such as relative antioxidant capacity, total phenolics content, flavonoids, anthocyanins, vitamin C and related enzyme activities (PAL, POD, PPO) were considered. In addition, correlations with possible candidate genes for chilling injury (CI) tolerance were searched by qPCR. Although a low susceptibility to CI symptoms has been found in “Big Top”, rootstocks “PADAC 9902-01”, “PADAC 99-05” and “ReplantPAC” exhibited lower CI symptoms. A statistically significant influence of the evaluated rootstocks was found concerning the parameters of this study. Phenols and anthocyanins seem to be important parameters to be considered in the prevention of chilling injury disorders. Moreover, PAL1, PPO4, PG2 and LDOX genes relative expressions were positively associated with chilling injury susceptibility. This study opens new perspectives for understanding peach fruit adaptation and response to cold storage temperatures during the post-harvest period. Full article

Peach fruit is one of the most economically widespread temperate fruits, whose productivity, and nutritional and sensory qualities are determined by interactions among several environmental and genetic factors, rootstocks, agronomic practices and pedo-climatic conditions. In recent years, climate change has prompted peach breeding programs to use specific rootstocks that are well adapted to unusual soil and climate characteristics, thus improving the plant’s adaptability and fruit quality. The aim of this work was to assess the biochemical and nutraceutical profile of two different peach cultivars, considering their growth on different rootstocks over three crop years. An analysis was carried out evaluating the interactive effect of all factors (i.e., cultivars, crop years and rootstocks) revealing the advantages or disadvantages on growth of the different rootstocks. Soluble solids content, titratable acidity, total polyphenols, total monomeric anthocyanins and antioxidant activity in fruit skin and pulp were analyzed. An analysis of variance was performed to assess the differences between the two cultivars considering the effect of rootstock (one way) and crop years, rootstocks and their interaction (two ways). In addition, two principal component analyses were performed separately on the phytochemical traits of the two cultivars to visualize the distributions of the five peach rootstocks during the three crop years. The results showed that fruit quality parameters are strongly dependent on cultivars, rootstocks and climatic conditions. All these aspects could be useful for the choice of rootstock in relation to agronomic management, making this study a valuable tool for choosing the best rootstock, considering simultaneously more factors affecting peaches’ biochemical and nutraceutical profile. Full article

Peach trees play an essential role as an economic crop in China. However, the increasing cost of labor has led to a decline in the benefits of peach cultivation. The use of dwarfing rootstock technology can increase planting density, reduce tree height, decrease labor requirements, and reduce production costs. The Cerasus humilis (Bge). Sok. is a promising dwarfing rootstock for peaches owing to its small tree size, abundant resources, strong resistance, and adaptability. In this study, we investigated the effect of Cerasus humilis rootstocks on peach growth and development, and related gene expression. We used Ruipan 4/Cerasus humilis and Ruipan 4/Amygdalus persica L. as experimental materials to measure the growth and fruiting characteristics of two-year-old Cerasus humilis rootstocks. In addition, we used bioinformatic methods to explore the effect of Cerasus humilis rootstock on peach growth gene expression. Our results showed that Cerasus humilis rootstocks can dwarf peach trees, reduce branches, increase pollen count and stigma receptivity, shorten spore development, and promote protein accumulation in the late stage of fruit maturity. The Cerasus humilis rootstock reduced the growth hormone content in peach trees while upregulating the expression of growth-related PpYucca5 and PpYucca2 genes. PpYucca6 expression was downregulated in the early stage of shoot growth and upregulated in the middle stage. By reducing the content of growth hormones, peach trees can be dwarfed, but their impact on fruit quality is minimal. These results indicate that Cerasus humilis is a suitable peach dwarfing rootstock and can provide a theoretical reference for the future breeding of peach dwarfing rootstocks. Full article

The spatial arrangement and growth pattern of root systems, defined by the root system architecture (RSA), influences plant productivity and adaptation to soil environments, playing an important role in sustainable horticulture. Florida’s peach production area covers contrasting soil types, making it necessary to identify rootstocks that exhibit soil-type-specific advantageous root traits. In this sense, the wide genetic diversity of the Prunus genus allows the breeding of rootstock genotypes with contrasting root traits. The evaluation of root traits expressed in young seedlings and plantlets facilitates the early selection of desirable phenotypes in rootstock breeding. Plantlets from three peach × (peach × almond) backcross populations were vegetatively propagated and grown in rhizoboxes. These backcross populations were identified as BC1251, BC1256, and BC1260 and studied in a completely randomized design. Scanned images of the entire root systems of the plantlets were analyzed for total root length distribution by diameter classes, root dry weight by depth horizons, root morphological components, structural root parameters, and root spreading angles. The BC1260 progeny presented a shallower root system and lower root growth. Backcross BC1251 progeny exhibited a more vigorous and deeper root system at narrower root angles, potentially allowing it to explore and exploit water and nutrients in deep sandy entisols from the Florida central ridge. Full article

The content of macro and microelements in the leaves of peach trees treated with biochar, organic fertilization and microorganisms in the field experiment was tested. The experiment was carried out in accordance with the integrated fruit production methods at the NIHR Experimental Orchard in Dąbrowice, from 2015 to 2017. The trees were grafted on P. persica Mandżurska rootstock and planted in the spring of 2013. In 2014, the following products were applied around the trees and mixed into the topsoil: biochar at a dose of 1.6 kg/tree (2000 kg/ha); biochar at a dose of 1.6 kg/tree used together with microorganisms—bacteria Pseudomonas fluorescens, Pantoea and arbuscular mycorrhizal fungi—Glomus caledonium, Glomus intraradices and Glomus coronatum; biochar at a dose of 1.6 kg/tree applied together with Florovit NPK organic fertilizer at a dose of 0.2 kg/tree; Florovit NPK; microorganisms—bacteria Pseudomonas fluorescens, Pantoea and arbuscular mycorrhizal fungi—Glomus caledonium, Glomus intraradices and Glomus coronatum; Florovit NPK organic fertilizer with the same microorganisms; and an untreated control. The average results showed that, compared to the control, the biochar increased the nitrogen content in the leaves by 6%. All experimental combinations increased the content of P and K in the leaves. The most effective at increasing the content of phosphorus in leaves—by 48%—was Florovit. The greatest increase in potassium was after the use of biochar with Florovit—by 38%. The magnesium content ranged from 0.49 to 0.59 g/100 g DW. The highest content of Mg was found in the leaves after the application of biochar with Florovit, and the lowest after the use of biochar alone. The leaves of the trees fertilized with the Florovit organic fertilizer had the lowest calcium content, while the highest calcium content was found in combination with trees treated with biochar only. The use of biochar alone did not increase the content of boron in the leaves compared to the control. In all other combinations, a higher amount of boron was found. The highest—18% more than the control of this microelement had leaves where biochar and Florovit were used. Trees treated with biochar and microorganisms accumulated the least copper in the leaves, while the highest content of this element was found in the combination where biochar fertilization was applied together with Florovit. Lower iron concentrations in peach leaves were found as a result of applying microorganisms, microorganisms with the organic fertilizer and biochar, relative to organic fertilization and the control combination. Trees where only microorganisms were applied to the soil had the least manganese and zinc in the leaves. The accumulation of manganese in the leaves was most favored by fertilization with biochar together with microorganisms, and the zinc content was the highest after the use of biochar alone. In general, studies have shown that a small dose of biochar alone or biochar together with organic fertilizer is a very effective method of feeding peach trees. More research is needed on the use of microorganisms and methods of their application with various products used in orchard fertilization. Full article

Plant distant grafting can produce stable genetic variation, which is a new method for germplasm innovation. Two chimeras, peach/apricot (PA) and apricot/peach (AP), were created through two-way grafting between peach and apricot. The leaves, flowers and fruit phenotypes of chimeras were significantly different to self-rooted rootstock. In order to investigate the causes of such changes, transcriptome and proteome integrative analyses were conducted on apricots from these two chimeras. Many differentially expressed genes (DEGs) and differentially expressed proteins (DEPs) that may be connected to the development of grafted apricot hybrids were identified and explored based on function. Moreover, we found 76 genes in forward-grafted PA and 46 in reverse-grafted AP that overlapped both in DEGs and DEPs (DEGs/DEPs) via transcriptome–proteome integrative analysis. Mapping the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway database in PA and AP, the top significant enrichment pathways of DEGs/DEPs included lipid metabolism (fatty acid elongation, cutin, suberine and wax biosynthesis, fatty acid degradation and alpha-linolenic acid metabolism) and carbohydrate metabolism (glycolysis/gluconeogenesis, starch and sucrose metabolism and galactose metabolism), revealing that lipid metabolism and carbohydrate metabolism may play an irreplaceable role in the development of grafted apricot hybrids. Taken together, this work uncovered numerous candidate transcripts and proteins involved in the development of grafted apricot hybrids. The molecular mechanisms provide new insights into this important process in other heterografting hybrids. Full article