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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.

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.

Most deciduous fruit trees cultivated in the temperate zone require a genotype-dependent amounts of chilling exposure for dormancy release and bud break. In Japanese apricot (Prunus mume), DORMANCY-ASSOCIATED MADS-box 6 (PmDAM6) may influence chilling-mediated dormancy release and bud break. In this study, we attempted to elucidate the biological functions of PmDAM6 related to dormancy regulation by analyzing PmDAM6-overexpressing transgenic apple (Malus spp.). We generated 35S:PmDAM6 lines and chemically inducible overexpression lines, 35S:PmDAM6-GR. In both overexpression lines, shoot growth was inhibited and early bud set was observed. In addition, PmDAM6 expression repressed bud break competency during dormancy and delayed bud break. Moreover, PmDAM6 expression increased abscisic acid levels and decreased cytokinins contents during the late dormancy and bud break stages in both 35S:PmDAM6 and 35S:PmDAM6-GR. Our analysis also suggested that abscisic acid levels increased during dormancy but subsequently decreased during dormancy release whereas cytokinins contents increased during the bud break stage in dormant Japanese apricot buds. We previously revealed that PmDAM6 expression is continuously down-regulated during dormancy release toward bud break in Japanese apricot. The PmDAM6 expression pattern was concurrent with a decrease and increase in the abscisic acid and cytokinins contents, respectively, in dormant Japanese apricot buds. Therefore, we hypothesize that PmDAM6 represses the bud break competency during dormancy and bud break stages in Japanese apricot by modulating abscisic acid and cytokinins accumulation in dormant buds.

Leaf senescence and abscission in autumn are critical phenological events in deciduous woody perennials. After leaf fall, dormant buds remain on deciduous woody perennials, which then enter a winter dormancy phase. Thus, leaf fall is widely believed to be linked to the onset of dormancy. In Rosaceae fruit trees, DORMANCY-ASSOCIATED MADS-box (DAM) transcription factors control bud dormancy. However, apart from their regulatory effects on bud dormancy, the biological functions of DAMs have not been thoroughly characterized. In this study, we revealed a novel DAM function influencing leaf senescence and abscission in autumn. In Prunus mume, PmDAM6 expression was gradually up-regulated in leaves during autumn toward leaf fall. Our comparative transcriptome analysis using two RNA-seq datasets for the leaves of transgenic plants overexpressing PmDAM6 and peach (Prunus persica) DAM6 (PpeDAM6) indicated Prunus DAM6 may up-regulate the expression of genes involved in ethylene biosynthesis and signaling as well as leaf abscission. Significant increases in 1-aminocyclopropane-1-carboxylate accumulation and ethylene emission in DEX-treated 35S:PmDAM6-GR leaves reflect the inductive effect of PmDAM6 on ethylene biosynthesis. Additionally, ethephon treatments promoted autumn leaf senescence and abscission in apple and P. mume, mirroring the changes due to PmDAM6 overexpression. Collectively, these findings suggest that PmDAM6 may induce ethylene emission from leaves, thereby promoting leaf senescence and abscission. This study clarified the effects of Prunus DAM6 on autumn leaf fall, which is associated with bud dormancy onset. Accordingly, in Rosaceae, DAMs may play multiple important roles affecting whole plant growth during the tree dormancy induction phase.

The success of vegetative propagation in woody ornamentals is strongly influenced by the physiological age and positional origin of donor shoots, yet the underlying mechanisms linking topophytic origin, hormonal dynamics, and root system quality remain unclear. This study examined adventitious rooting, root system morphology, and endogenous phytohormone profiles in basal (inner/lower crown) and terminal (outer/upper crown) leafy cuttings of Prunus subhirtella ‘Autumnalis’ from a mature 60-year-old tree. Despite similar rooting success between cutting types (66.7%), basal cuttings produced more extensive root systems, with greater total length, surface area, and numbers of tips and forks, whereas terminal cuttings formed thicker roots and a higher proportion of coarse roots (> 2 mm). Free indole-3-acetic acid (IAA) peaked at 4 hours post-severance in both types. However, terminal cuttings exhibited elevated levels of IAA conjugates and oxidative metabolites, as well as transiently higher jasmonic acid immediately after excision indicating that they exhibited stronger stress after wounding compared with basal cuttings. In contrast, the basal cuttings maintained higher indole-3-butyric acid (IBA) and distinct 4-chloro-indole-acetic acid (4-Cl-IAA) dynamics. These results suggest that differences in auxin metabolism and jasmonate dynamics shape root system morphology and quality. Integrating topophytic origin and hormonal profiling provides valuable insights for optimizing clonal propagation and improving root system performance in woody ornamentals.

The aim was to explore the alterations in growth traits, physiological and biochemical characteristics of Prunus sibirica seedlings raised from spaceflight seeds. The seedlings cultivated by the “Shenzhou XII” spacecraft carrying the seeds of superior clones of P. sibirica were used to observe their growth traits and determine physiological indicators. The results showed that plant height of Prunus sibirica seedlings raised from spaceflight seeds increased by 18–34% and internode length increased by 8–26%, but the number of primary branches, secondary branches, and leaves showed no significant change compared to the ground control. Leaf length and width of Prunus sibirica seedlings raised from spaceflight seeds were significantly higher than those of the ground control, with leaf length, width, and area increasing to 1.21–1.80 times higher than that of the ground control. Furthermore, the antioxidant and osmoregulatory capacities of P. sibirica seedlings raised from spaceflight seeds were altered. The peroxidase (POD) activity and Malondialdehyde (MDA) content were increased in ST28, ST207, and ST507, while they were reduced in ST1 and ST453. Compared with the ground control, the content of soluble sugar(SS), starch (St), and free proline (Pro) were significantly or highly significantly increased in all lines. The content of soluble protein (SP) was significantly increased in ST1, ST28, ST207, and ST507, while there was no significant change in ST453. P. sibirica seedlings raised from spaceflight seeds exhibited increased leaf pigment content, the interstitial CO 2 concentration (Ci), net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr). In conclusion, compared with the ground control, the growth indexes and physiological characteristics of Prunus sibirica seedlings raised from spaceflight seeds were changed, and the direction of change was different for different lines. This provided a foundation for subsequent germplasm improvement and variety selection.

Background Prunus sibirica L. is one of the most pivotal eco-economic tree species in China’s arid and semi-arid areas. The phenomenon of physiological fruit drop in P. sibirica L. is severe, and understanding fruit growth patterns and drop characteristics is crucial for high-quality cultivar production. However, there are few reports on P. sibirica fruit development and physiological fruit drop. Results In this study, we investigated the characteristics of fruit development, vegetative bud outgrowth, and fruit abscission, and explored the dynamic features of sugar metabolism in different tissues during physiological fruit drop and its relationship with fruit drop. The results showed that the fruit and vegetative bud outgrowth of the “Shanxing No. 1” variety exhibited an S-shaped growth pattern with three physiological stages. The flower and fruit drop of “Shanxing No. 1” lasted for about 70 days with an 89.73% total drop rate and three abscission peaks, which could be divided into the flower abscission stage mainly caused by pistil abortion, rapid fruitlet abscission stage, mainly caused by carbohydrate competition between the fruit and vegetative bud outgrowth; and slow fruit abscission stage mostly related to seed abortion. The perspective of the vegetative buds removal experiment further proved the competition between fruitlet and vegetative bud outgrowth simultaneously. During physiological fruit drop, the sugar contents and activities of sucrose metabolism enzymes in different tissues showed regular changes, corresponding to the dynamic law of fruit drop. Sucrose metabolism was mainly dominated by decomposition, and the enzymes involved in sucrose decomposition played a significant role. Acid invertase and sucrose synthase (decomposition direction) were the key enzymes regulating fruit abscission in P. sibirica L. Conclusions These results laid a foundation for revealing the physiological characteristics and physiological mechanism of P. sibirica L. fruit development, and also provided a theoretical basis for high-quality and high-yield cultivation of P. sibirica L.

Pink-flowered Prunus sibirica , of the genus Prunus , is an exceptional germplasm resource with high ornamental value. Understanding the mechanism behind petal coloration is crucial for cultivating ornamental P. sibirica varieties. This study utilized pink-flowered and white-flowered P. sibirica petals at different stages of flowering to explore the relationship between various physiological indicators, anatomical structures of petals, and flower coloration during flowering. Results indicated that anthocyanins, key pigment indicators in pink-flowered P. sibirica , directly influenced the a* values (redness). Increased activity of phenylalanine deaminase (4.43–29.69 U/g), chalcone isomerase (9.80–46.67 U/g), and soluble sugar content (29.25–35.28 mg/g) promoted anthocyanin synthesis and accumulation. These substances indirectly affected flower color by influencing anthocyanin content through physiological processes related to petal coloration. Structural changes in epidermal cells of pink and white flower petals during flowering were similar, with differences in pigment content and distribution impacting petal light absorption. Correlation analysis revealed that a* values were significantly and positively correlated with five factors, one of which was anthocyanin content, and significant negative correlations with soluble protein content and cytosol pH. This study examined the factors influencing petal coloration in pink-flowered P. sibirica from both physiological and anatomical perspectives, providing a theoretical foundation for breeding new varieties of ornamental flowering plants.

Background Flesh color is one of the most important traits for the commercial value of peach fruit. To unravel the underlying regulatory network in Prunus mira , we performed an integrated analysis of the transcriptome and metabolome of 3 fruit types with various flesh pigmentations (milk-white, yellow and blood) at 3 developmental stages (pit-hardening, cell enlargement and fruit ripening). Results Transcriptome analysis showed that an intense transcriptional adjustment is required for the transition from the pit-hardening to the cell enlargement stage. In contrast, few genes were differentially expressed (DEGs) from the cell enlargement to the fruit ripening stage and importantly, the 3 fruits displayed diverse transcriptional activities, indicating that difference in fruit flesh pigmentations mainly occurred during the ripening stage. We further investigated the DEGs between pairs of fruit types during the ripening stage and identified 563 DEGs representing the ‘ core transcriptome ’ associated with major differentiations between the 3 fruit types, including flesh pigmentation. Meanwhile, we analyzed the metabolome, particularly, at the ripening stage and uncovered 40 differential metabolites (‘ core metabolome ’) between the 3 fruit types including 5 anthocyanins, which may be the key molecules associated with flesh coloration. Finally, we constructed the regulatory network depicting the interactions between anthocyanins and important transcripts involved in fruit flesh coloration. Conclusions The major metabolites and transcripts involved in fruit flesh coloration in P. mira were unraveled in this study providing valuable information which will undoubtedly assist in breeding towards improved fruit quality in peach.

The fruit of melting-flesh peach (Prunus persica L. Batsch) cultivars produce high levels of ethylene caused by high expression of PpACS1 (an isogene of 1-aminocyclopropane-1-carboxylic acid synthase), resulting in rapid fruit softening at the late-ripening stage. In contrast, the fruit of stony hard peach cultivars do not soften and produce little ethylene due to low expression of PpACS1. To elucidate the mechanism for suppressing PpACS1 expression in stony hard peaches, a microarray analysis was performed. Several genes that displayed similar expression patterns as PpACS1 were identified and shown to be indole-3-acetic acid (IAA)-inducible genes (Aux/IAA, SAUR). That is, expression of IAA-inducible genes increased at the late-ripening stage in melting flesh peaches; however, these transcripts were low in mature fruit of stony hard peaches. The IAA concentration increased suddenly just before harvest time in melting flesh peaches exactly coinciding with system 2 ethylene production. In contrast, the IAA concentration did not increase in stony hard peaches. Application of 1-naphthalene acetic acid, a synthetic auxin, to stony hard peaches induced a high level of PpACS1 expression, a large amount of ethylene production and softening. Application of an anti-auxin, α-(phenylethyl-2-one)-IAA, to melting flesh peaches reduced levels of PpACS1 expression and ethylene production. These observations indicate that suppression of PpACS1 expression at the late-ripening stage of stony hard peach may result from a low level of IAA and that a high concentration of IAA is required to generate a large amount of system 2 ethylene in peaches.