Search Results (13)

The integration of HS-SPME-GC/MS and UPLC-MS/MS techniques enabled the profiling of volatile organic compounds (VOCs) and amino acids (AAs) in 18 crabapple flower cultivars, facilitating the development of a novel VOC–AA model. Among the 51 identified VOCs, benzyl alcohol, benzaldehyde, and ethyl benzoate were predominant, categorizing cultivars into fruit-almond, fruit-sweet, and mixed types. The amino acids, namely glutamic acid (Glu), asparagine (Asn), aspartic acid (Asp), serine (Ser), and alanine (Ala) constituted 83.6% of the total AAs identified. Notably, specific amino acids showed positive correlations with key VOCs, suggesting a metabolic regulatory mechanism. The Orthogonal Partial Least Squares Discriminant Analysis (OPLS-DA) model, when combined with volatile organic compounds (VOCs) and amino acid profiles, enabled more effective aroma type classification, providing a robust foundation for further studies on aroma mechanisms and targeted breeding. Full article

The edible value of crabapple flowers remains unreported. In this study, the flower buds of three crabapple cultivars with different flower colors, Malus ‘Royalty’ (purple-red), ‘May’s Delight’ (pink), and ‘Snowdrift’ (white), were processed via hot-air drying at different temperatures and durations. The results showed that the sensory scores of ‘Royalty’ (4 h at 50 °C or 6 h at 40 °C), ‘Snowdrift’ (5 h at 50 °C), and ‘May’s Delight’ (4 h at 60 °C or 6 h at 50 °C) were higher (score > 90 points). The contents of phloridzin, total flavonoids (TFC), and total free amino acids (TFAC) in ‘May’s Delight’ under 50 or 60 °C were significantly higher than in other treatments. The differences in functional constituents among the different treatments of ‘Royalty’ were the smallest (C.V < 7%). The influences (C.V_k > 35%) of cultivar and drying temperature on the phlorizin content (PC) and TFAC were significantly higher than those of other treatments. The PC maintained the highest stability (C.V_k < 10%) under different temperatures and durations. The value of color parameter a* of dry flowers was significantly positively correlated with TFC, PC, and TFAC, and the total score of the sensory evaluation was positively correlated with the TFC. Based on functional constituents and sensory evaluation, ‘May’s Delight’ with air-drying at 50 °C for 6 h was the best option for crabapple flower tea. Full article

Malus ‘Baiyun’ (registration no. 20210210), a new crabapple cultivar, was registered in 2021 by the Nanjing Forestry Unversity. However, the difficult rooting has greatly limited the production of high-quality M. ‘Baiyun’ in industrialization development. There is thus a pressing need to develop an organogenesis protocol for the in vitro propagation of M. ‘Baiyun’ to alleviate a shortage of high-quality M. ‘Baiyun’ seedlings. The results showed that choosing the apical bud in mid-March was an excellent explant material. To promote proliferation, the highest proliferation (6.27) of apical shoots was cultured on Murashige and Skoog (MS) medium supplemented with 0.5 mg·L⁻¹ 6-benzylaminopurine(6-BA) + 0.05 mg·L⁻¹ indole-3-butyric acid (IBA). Subsequently, a 100% rooting rate, average number of roots per shoot of 6.2 and maximum length of roots of 4.96 cm were obtained on half-strength Murashige and Skoog (1/2 MS) medium with the application of 0.5 mg·L⁻¹ naphthaleneacetic acid (NAA) or 0.6 mg·L⁻¹ NAA + 0.7 mg·L⁻¹ IBA. Additionally, thick and lateral roots were obtained with 0.6 mg·L⁻¹ NAA + 0.7 mg·L⁻¹ IBA. Our study is the first to establish an effective organogenesis protocol for new crabapple cultivars using stem segments. Full article

The Chinese pearleaf crabapple tree, belonging to the Rosaceae family and with the scientific name Malus asiatica, bears fruits that serve as both food and medicine. The Horqin Right Wing Front Banner is a critical node for ecological security in the northern border regions of China, exerting significant influence on ecological health in China. Additionally, the resources in this region are limited, and residents have historically relied solely on maize cultivation for sustenance. Therefore, local measures combining ecological conservation and economic development have been implemented in vigorously promoting the Chinese pearleaf crabapple industry. Hence, it is necessary to study the ecological suitability of the local Chinese pearleaf crabapple. In this study, 15 evaluation indicators are employed for this purpose, with the analytic hierarchy process (AHP) used to calculate single-factor weights. Additionally, GIS is utilized to establish membership functions for achieving dimensionless evaluation indicators, as well as a weighted index and model used to compute comprehensive suitability scores. Using the natural breakpoint method, the overall scores were categorized into five groups: most suitable, more suitable, barely suitable, unsuitable, and not applicable. The validation of zoning results includes verification of existing planting locations and conducting principal component analysis of the characteristics and yield of Chinese pearleaf crabapple to ensure the accuracy of the zoning. It is found that the validation results are generally consistent with the zoning results. The results indicate that the most suitable, more suitable, suitable, barely suitable, and unsuitable represent 16.49%, 32.07%, 30.36%, 14.52%, and 6.55% of the total zoning area, respectively. These findings can be applied to land use planning and in expanding the planting area of Chinese pearleaf crabapple. Full article

The Malus crabapple is an important woody ornamental plant. The fading of petals during its development significantly affects their ornamental value. Petal color is related to anthocyanin content and miRNAs play an important role in the post-transcriptional regulation of anthocyanin synthesis. However, the mechanisms underlying miRNA regulation of petal fading have rarely been studied. Transcriptome and small RNA sequencing of petals from the blooming phases of Malus. ‘Indian Summer’ varieties S1 (small bud), S2 (initial-flowering), and S3 (late-flowering) allowed us to identify 230 known miRNAs and 17 novel miRNAs, including 52 differentially expressed miRNAs which targeted 494 genes and formed 823 miRNA–target pairs. Based on the target gene annotation results, miRNA–target pairs were screened that may be involved in the fading process of Malus crabapple petals through three different pathways: anthocyanin synthesis, transport, and degradation, involving mcr-miR858-MYB1\MYB5 and mcr-miR396-McCHI inhibiting anthocyanin synthesis; mcr-miR167, mcr-miR390, mcr-miR535, and mcr-miR858 inhibiting anthocyanin transport from the cytoplasm to the vacuole by targeting ABC transporter genes (ABCB, ABCC, ABCD, and ABCG); and mcr-miR398 targeting the superoxide dismutase genes (CZSOD2 and CCS) to accelerate anthocyanin degradation. These findings offer a novel approach to understanding the mechanism of petal fading and serve as a reference for other plants with floral fading. Full article

Apple geminivirus 1 (AGV) in the genus Maldovirus of the family Geminiviridae was first identified infecting apple trees in the year 2015 in China. In this work, we characterized three isolates of the AGV in the Chinese pearleaf crabapple (Malus asiatica) in Inner Mongolia Autonomous Region. The viruses were detected by Illumina sequencing and its existence was confirmed by reverse transcription-polymerase chain reaction (RT-PCR) amplification of an AGV fragment. Between the three AGV isolates and the initially characterized AGV isolate PL2015, the nucleotide sequence identities of the complete genome ranged from 91.2 to 91.7%, of the coat protein gene (V1) ranged from 95.4% to 97.3%, and of the replicase gene (C1) ranged from 87.3% to 88.0%. Phylogenetic analysis indicated that the three isolates formed a monophyletic group together with the AGV, separated from the current genera in the family Geminiviridae. This is the first description of the AGV infecting crabapples. Full article

Apple (Malus x domestica) fruit size is dependent on cell division and cell expansion, processes that are subsequently regulated by plant hormones such as auxins, gibberellins, and cytokinins. In this study, we investigated the role of cell division and cell expansion in apple growth and identified which of the two was more deterministic of final fruit size. Three cultivars of different sizes were selected, namely, “Twenty Ounce” (large-sized), “Royal Gala” (medium-sized), and “Crabapple” (small-sized). Gene expression and cell size analyses were conducted over the course of two consecutive seasons. The expression patterns of three classes of genes were markedly similar across all cultivars. Two cell division markers, namely MdCDKB2;2 and MdANT2, were discovered to be correlatively expressed, as both displayed initially high expression levels, which gradually declined from the early to late stages of the growth time course. For cell expansion markers, MdEXP3 was upregulated as the cells expanded, while MdARF106 was expressed in both the cell division and expansion stages. Meanwhile, the ripening-related gene MdACO1 was expectedly expressed only during the ending stages associated with ripening. Interestingly, the cell measurements taken regularly from each cultivar throughout the same experimental timespan showed that cell sizes were unaltered and remained constant from initial pollination at the zeroth Day After Pollination (DAP) to ripening at 120 Days After Full Bloom (DAFB). Full article

The synthesis of anthocyanin pigments in plants is known to be regulated by multiple mechanisms, including epigenetic regulation; however, the contribution of the RNA-directed DNA methylation (RdDM) pathway is not well understood. Here, we used bisulfite sequencing and Real Time (RT)-quantitative (q) PCR to analyze the methylation level of the promoter of constitutively photomorphogenic 1 (McCOP1) from Malus cv. spp, a gene involved in regulating anthocyanin biosynthesis. The CHH methylation level of the McCOP1 promoter was negatively correlated with McCOP1 RNA expression, and inhibiting DNA methylation caused decreased methylation of the McCOP1 promoter and asymmetric cytosine CHH methylation. We observed that the McCOP1 promoter was a direct target of the RdDM pathway argonaute RISC component 4 (McAGO4) protein, which bound to a McCOP1 promoter GGTTCGG site. Bimolecular fluorescence complementation (BIFC) analysis showed that RNA-directed DNA methylation (McRDM1) interacted with McAGO4 and another RdDM protein, domains rearranged methyltransferase 2 (McDRM2), to regulate the CHH methylation of the McCOP1 promoter. Detection of CHH methylation and COP1 gene expression in the Arabidopsis thalianaatago4, atdrm2 and atrdm1 mutants showed that RDM1 is the effector of the RdDM pathway. This was confirmed by silencing McRDM1 in crabapple leaves or apple fruit, which resulted in a decrease in McCOP1 CHH methylation and an increase in McCOP1 transcript levels, as well as in anthocyanin accumulation. In conclusion, these results show that the RdDM pathway is involved in regulating anthocyanin accumulation through CHH methylation of the McCOP1 promoter. Full article

Flowering crabapples are a series of precious ornamental woody plants. However, their growth and development are inhibited in the subtropical regions due to the weak photosynthesis under high-temperature environment in the summer. Chlorophyll a fluorescence transient and 2-dimensional electrophoresis (2-DE) analyses were conducted to investigate the response characteristics of photosynthesis under simulated 38 °C heat stress in leaves of Malus. ‘Prairifire’, a spring-red leaf cultivar of flowering crabapple with strong thermal adaptability. In the present study, the net photosynthetic rate (Pn) was significantly decreased during the heat shock process, which showed a similar trend to the stomatal conductance (Gs), indicating a sensitive stomatal behavior to heat stress. Moreover, an efficient reaction center in photosystem II (PSII), and a functionally intact oxygen-evolving complex (OEC) conferred strong photosynthetic adaptability under heat stress. The higher level of transketolase (TK) under 48-h heat shock treatment was considered a protective mechanism of photosynthetic apparatus. However, heat stress inhibited the functions of light harvesting complex II (LHCII), electron transport in PSII, and the levels of key enzymes in the Calvin cycle, which were considered as the reasons causing an increase in the proportion of non-stomatal restrictions. Full article

Flowering crabapple is an important ornamental flower. It is vital to understand the floral scent properties and the associated release dynamics for carrying out fragrant flower breeding or floral regulation of crabapple. Static headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry was used to detect the volatile compounds in Malus ioensis “Prairie Rose” flowers at different flowering stages and at different day-night time. The results showed that methylheptenone, phenylethanol, geranylacetone, 2-(4-methoxyphenyl)ethanol, α-cedrene were the major compounds in M. ioensis “Prairie Rose”, but the compounds released during different stages and different day-night time were significantly different (P < 0.0001). A total of 25 volatile compounds were identified from the four flowering stages. The floral scents in the initial and flowering stages were the most similar (dissimilarity 0.21). The main compounds in these two stages were geranylacetone and methylheptenone, and the contents of geranylacetone and phenylethanol were positively correlated with the flowering stages. From the bud stage to the end of flowering, the total amount of volatile compounds released showed an initial increase followed by a decrease and the amounts of compounds released during the initial flowering stage were the highest. The aliphatic and benzenoids content was significant higher in the daytime than at night. A total of 15 compounds were detected in the five time periods. Methylheptenone and phenylethanol were particularly released in the 10:00–12:00 and 15:00–17:00 time periods. There were only three common compounds among the five time periods and the types of flower volatiles released during the daytime were obviously higher than those released at night. From the nocturnal to diurnal, the amount of flower volatiles released first increased, then decreased, and the release reached a peak between 10 am and 12 noon, which was consistent with the pollination biological characteristics of Malus flowers. Our findings are important for understanding the mechanism of insect visits to crabapple and the regulation of crabapple flower scent. Full article

Double-flower ornamental crabapples display eye-catching morphologies in comparison to single flower, but the genetic basis of double-flower development is not yet well known in apples. In order to comprehensively understand the differential expression of genes (DEGs) between single and double flower, the transcriptome of double flower crabapples Malus Kelsey, Malus micromalus, Malus Royalty, and a single flower cultivar Malus Dolgo were compared by RNA-sequencing. The results showed that there were 1854 genes in overlapped DEGs among all sample comparisons in apple single and double flower varieties. A large number of development and hormone related DEGs were also recognized on the basis of GO and KEGG annotations, and most of the genes were found to be down-regulated in double flowers. Particularly, an AGL24-MADS-box gene (MD08G1196900) and an auxin responsive gene (MD13G1137000) were putatively key candidate genes in the development of double flower by weighted gene co-expression network analysis (WGCNA). The study provides insights into the complex molecular mechanism underlying the development of the double flower in apple. Full article

Malus hupehensis belongs to the Malus genus (Rosaceae) and is an indigenous wild crabapple of China. This species has received more and more attention, due to its important medicinal, and excellent ornamental and economical, values. In this study, the whole chloroplast (cp) genome of Malus hupehensis, using a Hiseq X Ten sequencing platform, is reported. The M. hupehensis cp genome is 160,065 bp in size, containing a large single copy region (LSC) of 88,166 bp and a small single copy region (SSC) of 19,193 bp, separated by a pair of inverted repeats (IRs) of 26,353 bp. It contains 112 genes, including 78 protein-coding genes (PCGs), 30 transfer RNA genes (tRNAs), and four ribosomal RNA genes (rRNAs). The overall nucleotide composition is 36.6% CG. A total of 96 simple sequence repeats (SSRs) were identified, most of them were found to be mononucleotide repeats composed of A/T. In addition, a total of 49 long repeats were identified, including 24 forward repeats, 21 palindromic repeats, and four reverse repeats. Comparisons of the IR boundaries of nine Malus complete chloroplast genomes presented slight variations at IR/SC boundaries regions. A phylogenetic analysis, based on 26 chloroplast genomes using the maximum likelihood (ML) method, indicates that M. hupehensis clustered closer ties with M. baccata, M. micromalus, and M. prunifolia than with M. tschonoskii. The availability of the complete chloroplast genome using genomics methods is reported here and provides reliable genetic information for future exploration on the taxonomy and phylogenetic evolution of the Malus and related species. Full article

Seven dihydrochalcone compounds were isolated from the leaves of Malus crabapples, cv. “Radiant”, and their chemical structures were elucidated by UV, IR, ESI-MS, ¹H-NMR and ¹³C-NMR analyses. These compounds, which include trilobatin (A1), phloretin (A2), 3-hydroxyphloretin (A3), phloretin rutinoside (A4), phlorizin (A5), 6′′-O-coumaroyl-4′-O-glucopyranosylphloretin (A6), and 3′′′-methoxy-6′′-O-feruloy-4′-O-glucopyranosyl-phloretin (A7), all belong to the phloretin class and its derivatives. Compounds A6 and A7 are two new rare dihydrochalcone compounds. The results of a MTT cancer cell growth inhibition assay demonstrated that phloretin and these derivatives showed significant positive anticancer activities against several human cancer cell lines, including the A549 human lung cancer cell line, Bel 7402 liver cancer cell line, HepG2 human ileocecal cancer cell line, and HT-29 human colon cancer cell line. A7 had significant effects on all cancer cell lines, suggesting potential applications for phloretin and its derivatives. Adding a methoxyl group to phloretin dramatically increases phloretin’s anticancer activity. Full article