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The dormancy-associated MADS-box (DAM) genes PpDAM5 and PpDAM6 have been shown to play important roles in bud endodormancy; however, their molecular regulatory mechanism in peach is unclear. In this study, by use of yeast one-hybrid screening, we isolated a TEOSINTE BRANCHED1/CYCLOIDEA/PROLIFERATING CELL FACTOR transcription factor, PpTCP20, in the peach cultivar ‘Zhongyou 4’ (Prunus persica var. nectarina). The protein was localized in the nucleus and was capable of forming a homodimer. Electrophoretic mobility shift assays demonstrated that PpTCP20 binds to a GCCCR element in the promoters of PpDAM5 and PpDAM6, and transient dual luciferase experiments showed that PpTCP20 inhibited the expression of PpDAM5 and PpDAM6 as the period of the release of flower bud endodormancy approached. In addition, PpTCP20 interacted with PpABF2 to form heterodimers to regulate bud endodormancy, and the content of abscisic acid decreased with the release of endodormancy. PpTCP20 also inhibited expression of PpABF2 to regulate endodormancy. Taken together, our results suggest that PpTCP20 regulates peach flower bud endodormancy by negatively regulating the expression of PpDAM5 and PpDAM6, and by interacting with PpABF2, thus revealing a novel regulatory mechanism in a perennial deciduous tree.

Low-cost, high throughput genotyping methods are crucial to marker discovery and marker-assisted breeding efforts, but have not been available for many 'specialty crops' such as fruit and nut trees. Here we apply the Genotyping-By-Sequencing (GBS) method developed for cereals to the discovery of single nucleotide polymorphisms (SNPs) in a peach F2 mapping population. Peach is a genetic and genomic model within the Rosaceae and will provide a template for the use of this method with other members of this family. Our F2 mapping population of 57 genotypes segregates for bloom time (BD) and chilling requirement (CR) and we have extensively phenotyped this population. The population derives from a selfed F1 progeny of a cross between 'Hakuho' (high CR) and 'UFGold' (low CR). We were able to successfully employ GBS and the TASSEL GBS pipeline without modification of the original methodology using the ApeKI restriction enzyme and multiplexing at an equivalent of 96 samples per Illumina HiSeq 2000 lane. We obtained hundreds of SNP markers which were then used to construct a genetic linkage map and identify quantitative trait loci (QTL) for BD and CR.

Rooting is considered a critical stage in the micropropagation of Prunus sp . because it controls plant survival during acclimatization. Auxins and genotype are thought to play a significant role in root formation and induction. Therefore, the objective of the present work was to evaluate the effect of different indole-3-butyric acid (IBA) concentrations on the in vitro rooting and acclimatization of the Okinawa, Nemared, and Garnem peach rootstocks. Microcuttings of 2–3 cm in length were cultivated in MS medium supplemented with IBA (0.0, 0.5, 1.0, 2.0, 3.0, and 4.0 mg L − 1 ) for the in vitro rooting stage. According to our results, the Garnem genotype exhibited the highest in vitro rooting rate, number of roots per plantlet, and root length. The level of 2.0 mg L − 1 of IBA was associated with rooting rates of 100%, 83.33%, and 75% for the Garnem, Okinawa, and Nemared, respectively. The Garnem genotype responded to 4.0 mg L − 1 of IBA with a fixed highest root number (12.33), which was the average number of roots per plantlet. Whereas, for the Nemared and Okinawa genotypes, the highest root number per plantlet was 8.00 and 5.00, respectively, in response to 3.0 mg L − 1 of IBA. The root lengths of the three genotypes varied significantly depending on the IBA treatment. The Garnem genotype presented the longest root length (5.33 cm), which was followed by the Okinawa genotype (2.49 cm), while the shortest value was presented with the Nemared (1.43 cm). The current study also demonstrated that the three genotypes developed abnormal roots and callus formation when the IBA concentration was increased to 4.00 mg L − 1 . Following acclimatization, the Garnem, Okinawa, and Nemared genotypes had respective average survival rates of 93%, 90%, and 75% for plantlets with fully grown shoots and roots.

Alkaline stress is considered as one of the major abiotic stress factors limiting plant production on a global scale. This study was conducted in vitro to evaluate the physiological, morphological, and biochemical responses of Garnem rootstock to NaHCO 3 -induced alkaline stress using sodium nitroprusside (SNP) and salicylic acid (SA) treatments. The aim was to alleviate the negative effects of alkaline stress. The study was conducted during the rooting stage of Garnem rootstock plantlets obtained through in vitro micropropagation. SNP and SA (50, 100, and 150 µM) were applied in vitro to counteract alkaline stress induced by NaHCO 3 (0 mM, 20 mM, and 40 mM) at various concentrations. As the severity of alkaline stress increased, damage occurred to morphological, physiological, and biochemical parameters. The SNP and SA treatments alleviated the harmful effects of alkaline stress. In the study, the highest survival rate was observed with 0 mM NaHCO 3  + 50 µM SA (98.33%) and 50 µM SNP (95.00%), while the lowest survival rate was observed with 40 mM NaHCO 3  + 150 µM SA (6.67%). The longest shoots were observed with 0 mM NaHCO 3  + 100 µM SNP (4.25 cm), and the shortest shoots were observed with 40 mM NaHCO 3  + 150 µM SA (0.77 cm). The highest number of leaves was found with 20 mM NaHCO 3  + 50 µM SA (20.63 per plantlet), and the lowest number of leaves was found with 20 mM NaHCO 3  + 150 µM SNP (5.33 per plantlet). The highest plant fresh weight was observed with the 0 mM NaHCO 3  + 50 µM SNP (2.07 g), while the lowest plant fresh weight was observed with the 20 mM NaHCO 3  + 150 µM SA (0.14 g) application. The highest plant dry weight was observed with the 0 mM NaHCO 3  + 150 µM SA (0.24 g), while the lowest plant dry weight was observed with the 20 mM NaHCO 3  + 150 µM SA and 40 mM NaHCO 3  + 150 µM SA (0.04 g) applications. The highest injury was observed with 40 mM NaHCO 3 + 50 µM SA, 40 mM NaHCO 3 + 100 µM SA and 40 mM NaHCO 3 + 150 µM SA (4.00) and the lowest injury was observed with 0 mM NaHCO 3 +50 µM SNP, 0 mM NaHCO 3 +100 µM SNP and 0 mM NaHCO 3 +150 µM SNP (1.00). Membrane permeability increased under high alkaline stress, while 100 µM SNP applications reduced this rate, contributing to the preservation of cellular structure. All SNP and 50 µM SA applications increased leaf relative water content in response to alkaline stress. Significant decreases in chlorophyll a, chlorophyll b, and total chlorophyll concentrations were observed under alkaline stress conditions. However, SNP treatments alleviated these negative effects and increased chlorophyll levels. Furthermore, SNP treatments significantly reduced hydrogen peroxide (H 2 O 2 ) and malondialdehyde (MDA) accumulations. Overall, the results demonstrated that SNP treatments at all tested concentrations effectively mitigated NaHCO 3 -induced alkaline stress by improving morphological traits, maintaining membrane integrity, enhancing leaf relative water content and reducing oxidative damage in Garnem rootstock plantlets. In contrast, salicylic acid exhibited a concentration-dependent response, with low doses (50–100 µM) alleviating stress effects, whereas the high concentration (150 µM) induced phytotoxicity and markedly suppressed plant growth and physiological performance.

Green and chemical‐free hot water (HW) treatment can effectively reduce the chilling injury of peach fruit; however, the mechanism of inducing chilling resistance by heat treatment is still unclear. This study found that HW treatment could activate reactive oxygen species (ROS) signalling, forming ROS‐Ca 2+ signalling. Furthermore, we identified a peach Ca 2+ sensor, calcium‐dependent protein kinase 29 (PpCDPK29), as a positive regulator of postharvest chilling resistance. PpCDPK29 interacted with ROS‐generating proteins (PpRBOHC/D) and antioxidant enzymes (PpSOD and PpCAT1) to jointly maintain ROS homeostasis. Meanwhile, we found that PpHSFA2a was phosphorylated by PpCDPK29 and transferred to the nucleus, which enhanced the binding ability of PpHSFA2a to the target genes. Here, PpHSFA2a activated the transcription of target genes PpHSP18.5 , PpHSP70 , PpGSTU7 , PpGSTU19 , PpGolS1 and PpBAM1 , acted as molecular chaperones, improved ROS scavenging and enhanced osmoregulation to alleviate postharvest chilling injury of peach fruit. In summary, HW treatment could alleviate postharvest chilling injury in peach fruit by activating the PpCDPK29‐mediated Ca 2+ ‐ROS and HSF‐HSP signalling pathways, providing a novel signalling network for postharvest quality control of peach fruit.

Peaches have a short shelf life and require chilling during storage and transport. Peach aroma is important for consumer preference and determined by underlying metabolic pathways and gene expression. Differences in aroma (profiles of volatile organic compounds, VOCs) have been widely reported across cultivars and in response to cold storage. However, few studies used intact peaches, or used equilibrium sampling methods subject to saturation. We analysed VOC profiles using TD-GC × GC-ToF-MS and expression of 12 key VOC pathway genes of intact fruit from six cultivars (three peaches, three nectarines) before and after storage at 1 °C for 7 days including 36 h shelf life storage at 20 °C. Two dimensional GC (GC × GC) significantly enhances discrimination of thermal desorption gas chromatography time-of-flight mass spectrometry (TD-GC-ToF-MS) and detected a total of 115 VOCs. A subset of 15 VOCs from analysis with Random Forest discriminated between cultivars. Another 16 VOCs correlated strongly with expression profiles of eleven key genes in the lipoxygenase pathway, and both expression profiles and VOCs discriminated amongst cultivars, peach versus nectarines and between treatments. The cultivar-specific response to cold storage underlines the need to understand more fully the genetic basis for VOC changes across cultivars.

In this study the sensitivity of peach tree (Prunus persica L.) to three water stress levels from mid-pit hardening until harvest was assessed. Seasonal patterns of shoot and fruit growth, gas exchange (leaf photosynthesis, stomatal conductance and transpiration) as well as carbon (C) storage/mobilization were evaluated in relation to plant water status. A simple C balance model was also developed to investigate sink-source relationship in relation to plant water status at the tree level. The C source was estimated through the leaf area dynamics and leaf photosynthesis rate along the season. The C sink was estimated for maintenance respiration and growth of shoots and fruits. Water stress significantly reduced gas exchange, and fruit, and shoot growth, but increased fruit dry matter concentration. Growth was more affected by water deficit than photosynthesis, and shoot growth was more sensitive to water deficit than fruit growth. Reduction of shoot growth was associated with a decrease of shoot elongation, emergence, and high shoot mortality. Water scarcity affected tree C assimilation due to two interacting factors: (i) reduction in leaf photosynthesis (-23% and -50% under moderate (MS) and severe (SS) water stress compared to low (LS) stress during growth season) and (ii) reduction in total leaf area (-57% and -79% under MS and SS compared to LS at harvest). Our field data analysis suggested a Ψstem threshold of -1.5 MPa below which daily net C gain became negative, i.e. C assimilation became lower than C needed for respiration and growth. Negative C balance under MS and SS associated with decline of trunk carbohydrate reserves--may have led to drought-induced vegetative mortality.

Late-spring frost events severely damage low-chill peach blossoms, causing significant yield losses. Although 5-aminolevulinic acid (ALA) enhances cold tolerance through the PpC3H37-PpWRKY18 module, the regulatory mechanism of ALA on PpC3H37 remains to be elucidated. Using yeast one-hybrid screening with the PpC3H37 promoter as bait, we identified PpDof9 as a key interacting transcription factor. A genome-wide analysis revealed 25 PpDof genes in peaches (Prunus persica). These genes exhibited variable physicochemical properties, with most proteins predicted as nuclear-localized. Subcellular localization experiments in tobacco revealed that PpDof9 was localized to the nucleus, consistent with predictions. A synteny analysis indicated nine segmental duplication pairs and tandem duplications on chromosomes 5 and 6, suggesting duplication events drove family expansion. A conserved motif analysis confirmed universal presence of the Dof domain (Motif 1). Promoter cis-element screening identified low-temperature responsive (LTR) elements in 12 PpDofs, including PpDof1, PpDof8, PpDof9, and PpDof25. The quantitative real-time PCR (qRT-PCR) results showed that PpDof1, PpDof8, PpDof9, PpDof15, PpDof16, and PpDof25 were significantly upregulated under low-temperature stress, and this upregulation was further enhanced by ALA pretreatment. Our findings demonstrate ALA-mediated modulation of specific PpDof TFs in cold response and provide candidates (PpDof1, PpDof9, PpDof8, PpDof25) for enhancing floral frost tolerance in peaches.

Drought is a major environmental stress severely restricting plant growth, development, and productivity in arid regions. In this research, seven interspecific peach × almond hybrids (‘GF677’, ‘GN15’, ‘GN2’, ‘TT’, ‘35.1’, ‘34.2’, and ‘50.10’) were evaluated for their drought stress tolerance to identify promising rootstocks. Drought stress treatments were applied at 40%, 60%, and 100% field capacity (FC). Following a two-month stress period, morphological, physiological, and biochemical traits, along with the concentrations of 10 elements in leaves and roots, were measured. Under severe drought stress, all rootstocks exhibited reductions in plant height, trunk diameter, new branch growth, root and shoot fresh and dry weights, and relative water content, with an increase in the number of necrotic and fallen leaves. Drought stress significantly impaired PSII efficiency. At 40% FC, rootstocks ‘TT’ (0.749) and ‘GF677’ (0.740) exhibited the highest QYmax, while rootstocks ‘50.10’ (0.650) and ‘34.2’ (0.688) had the lowest. Under 40% field capacity (FC) stress, protein content and the activities of APX and CAT decreased, while proline, antioxidant capacity, electrolyte leakage, and aldehyde levels increased. Under drought stress, ‘TT’ displayed higher leaf concentrations of N (2.08%), P (0.17%), Ca (1.45%), Mg (0.56%), Fe (184.71 mg kg −1 ), Cu (5.07 mg kg −1 ), and Zn (18.77 mg kg −1 ). In contrast, rootstock ‘50.10’ exhibited the highest concentrations of Cl (4.83%), P (0.24%), and Zn (18.85 mg kg −1 ) and the lowest concentrations of N, K, Ca, and Fe. Finally, this research introduces ‘TT’ rootstock as a promising drought-tolerant rootstock.

Peach ( Prunus persica , Rosaceae) is an extremely popular tree fruit worldwide, with an annual production near 20 million tons. Peach is widely thought to have origins in China, but its evolutionary history is largely unknown. The oldest evidence for the peach has been Chinese archaeological records dating to 8000–7000 BP. Here, we report eight fossil peach endocarps from late Pliocene strata of Kunming City, Yunnan, southwestern China. The fossils are identical to modern peach endocarps, including size comparable to smaller modern varieties, a single seed, a deep dorsal groove and presence of deep pits and furrows. These fossils show that China has been a critical region for peach evolution since long before human presence, much less agriculture. Peaches evolved their modern morphology under natural selection, presumably involving large, frugivorous mammals such as primates. Much later, peach size and variety increased through domestication and breeding.