R2R3-MYB transcription factors are central regulators of anthocyanin biosynthesis, but their role in coordinating the control of chlorophyll metabolism remains largely unexplored. Here, we identified a novel R2R3-MYB transcriptional repressor from pear, named PbrMYBL4. This nuclear-localized protein contains a canonical EAR repression motif and is predominantly expressed in the fruit pericarp. Functional analyses demonstrated that PbrMYBL4 could simultaneously inhibit anthocyanin accumulation and chlorophyll degradation. Mechanistically, it represses anthocyanin biosynthesis by directly downregulating key structural genes (PbrF3H and PbrANS) and by binding to the promoter of the master activator PbrMYB10b to suppress its transcription. Furthermore, PbrMYBL4 interacts with PbrbHLH3 to form a repressive complex that competitively disrupts the formation of the activating PbrMYB10b-PbrbHLH3 complex, thereby amplifying the repression of anthocyanin pathway genes. Concurrently, PbrMYBL4 could inhibit chlorophyll degradation by directly repressing the chlorophyll degradation gene PbrSGRL. Overall, these findings suggest that PbrMYBL4 could regulate pigment metabolism via distinct regulatory modules, PbrMYBL4-PbrMYB10b and PbrMYBL4-PbrSGRL. Importantly, our findings reveal a dual-function transcriptional regulator that fine-tunes fruit coloration, providing a strategic target for molecular breeding to improve pear fruit quality.

BACKGROUND AND AIMS:Anthocyanins, vital health-beneficial plant pigments, are regulated by structural genes and MYB-bHLH-WD40 complexes. Cultivated strawberry (Fragaria × ananassa) displays diverse fruit colors, with its anthocyanin profile mainly comprising nearly 70% pelargonidin and 30% cyanidin. Variations in this ratio lead to distinct fruit coloration, yet the regulatory mechanisms governing this proportion remain largely unknown. Here, via systematic analysis of anthocyanin metabolic patterns in five strawberry cultivars with contrasting fruit colors, we identified a molecular module controlling cyanidin biosynthesis in strawberry. METHODS:This study used five commercially cultivated strawberry cultivars with gradient fruit skin colors ('Zhenhongmeiling', 'Benihoppe', 'Kaorino', 'Fenyu No.2', 'Mengzhiying') as materials. We analyzed the anthocyanin metabolic regulatory network during fruit skin development via high-performance liquid chromatography (HPLC), RNA-seq, yeast hybridization and transient overexpression assays. KEY RESULTS:The results showed that pelargonidin-based anthocyanins dominated (54%-68%) in the red cultivars ('Zhenhongmeiling', 'Benihoppe', 'Kaorino'), while cyanidin-based anthocyanins were the main pigments (72%-85%) in pink ('Fenyu No.2') and white ('Mengzhiying') cultivars. RNA-seq and functional validation revealed that the low expression of most flavonoid structural genes reduced anthocyanin diversity and total content in pink/white strawberries, and weak FaLWD1-like expression decreased the transcriptional activation of FaMYB10 on target structural genes. Further verification confirmed that FaLWD1-like drastically elevated the activation of FaMYB10 on the FaF3'H promoter by 10.85-fold relative to the 35S control. Additionally, co-overexpression of FaLWD1-like and FaMYB10 increased cyanidin 3-O-glucoside content by 28%-29% in pink/white strawberries compared with FaMYB10 single overexpression. CONCLUSIONS:This study uncovers a novel mechanism where the FaLWD1-like-FaMYB10 module regulates cyanidin synthesis in strawberry, providing a novel target for the improvement of strawberry fruit coloration.

Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don] is an economically important Rosaceae fruit crop in China. Massive fruit abscission in the majority of large-fruited Chinese cherry landraces leads to a catastrophic yield loss, hindering the development of the Chinese cherry industry. Herein, we performed systematic physiological analyses to comprehensively characterize the dynamic changes in auxin-centered phytohormones during fruit development across four Chinese cherry landraces exhibiting varying degrees of fruit abscission. These analyses, along with exogenous indole-3-acetic acid (IAA) rescue experiments, confirmed that the endogenous phytohormone imbalance triggered by reduced IAA accumulation in embryos is the core cause of young fruit abscission. Transcriptomic profiling revealed divergent expression patterns of genes associated with IAA synthesis and transport in the embryo, pedicel, and flesh at two critical fruit developmental stages. Weighted gene co-expression network analysis prioritized the rate-limiting YUCCA flavin monooxygenase encoding gene CpYUC10B. Transient overexpression of CpYUC10B elevated IAA levels and upregulated polar auxin transporter gene CpPIN1 expression in embryos, pedicels, and flesh, while repressing the expression of cell wall hydrolase genes in pedicels, consequently reducing fruit abscission. Conversely, VIGS-mediated silencing produced opposite effects. Meanwhile, ectopic overexpression of CpYUC10B in tomato delayed distal pedicel abscission after flower removal, accompanied by elevated IAA levels in the abscission zone, upregulated expression of SlPIN1, and downregulated expression of cell wall hydrolase genes (SlEXLB1, SlBGL12, SlPG, and SlPME7). Collectively, our findings provide a valuable theoretical foundation and practical reference for enhancing yield stability, and offer a new target gene for the genetic improvement of large-fruited cultivars.

As a vital economic crop, enhancing fruit quality and extending postharvest shelf-life remain central research priorities in strawberry production. This study investigated the effects of blue light (BL) intensity on ripening and quality of four strawberry (Fragaria × ananassa Duch.) genotypes harvested at the white stage. All genotypes under BL treatment reached full maturity within 3-4 d. Physiological analyses revealed that BL treatment promoted fruit coloration, regulated hormonal synergies to accelerate ripening, improved intrinsic quality indices, and most effectively enhanced total antioxidant capacity. However, outcomes varied significantly with genotype and light intensity, with excessive intensity suppressing quality improvement. Among all treatments, 200 μmol m-2 s-1 blue light demonstrated optimal efficacy for quality enhancement in most genotypes ('Benihoppe', 'Fenyu No.1'). These results establish a theoretical foundation for optimizing BL intensity in strawberry production and validate its practical feasibility, while proposing early harvesting under BL as a novel strategy for shelf-life extension.

Anthocyanin, a pivotal metabolite governing red pigmentation in plant organs, is predominantly regulated by R2R3-MYB transcription factors. Leveraging 'Red zaosu', a spontaneous red-pericarp mutant originating from white pear, combined with phytohormone treatments (MeJA/ABA), this study elucidates the molecular mechanism whereby PbMYB30 orchestrates dynamic anthocyanin biosynthesis. Results indicate that PbMYB30, localized in the nucleus, transcriptionally activates anthocyanin accumulation via direct binding to the promoters of PbDFR and PbUFGT; however, formation of the MYB-bHLH-WD40(MBW) ternary complex with PbbHLH33 and PbWD40 substantially attenuates its transcriptional activation capacity. Protein-protein interactions within this complex were validated by yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) assays, and MBW ternary complex repressive role was confirmed via transient co-expression. Furthermore, exogenously applied MeJA and ABA enhanced anthocyanin synthesis by inducing PbMYB30 promoter activity. This work provides the first evidence of MBW complex-mediated functional repression of MYB in pear, establishing a molecular framework for targeted breeding of red-skinned pear cultivars.

Photosynthesis is a source of energy for various types of plant life activities and is essential for plant growth and development. Consequently, the study of photosynthetic mechanisms has been a hot spot. Leaf color mutants has always been ideal materials for exploring the mechanisms of chlorophyll metabolism and photosynthesis. In this study, we identified a leaf color mutant of 'Benihoppe' strawberry in the field, which exhibited a darker green leaf color compared with the wild type. The content of total chlorophyll and carotenoid in the mutant leaves was elevated by 7.44-20.23% and 8.9-21.92%, respectively, compared with that of the wild type. Additionally, net photosynthetic rate in the mutant increased by 20.13%. Further transcriptome analysis showed that significant upregulation of genes such as GLK1, PPR, and MORF9 in the mutant leaves, which promoted chloroplast development. The expression levels of UROD, PPOC, PORA, CHLG, and CPOX were significantly upregulated during chlorophyll synthesis, while the expression levels of HCAR and CYP89A9 were significantly downregulated during chlorophyll degradation, thus leading to the accumulation of chlorophyll in mutant leaves. The upregulation of gene expression levels such as PetM, AtpD, PGK, and RPI4 during photosynthesis promoted multiple stages of light and dark reaction, thereby enhancing the photosynthetic capacity of the mutant. And the changes in metabolites such as monogalactosyl monoacylglycerol (MGMG), glucuronosyldiacylglycerol (GlcADG), raffinose, etc. also indicate that the mutant has metabolic differences in chloroplast composition and photosynthesis compared to 'Benihoppe'. The above results not only deepen our understanding of the mechanism behind the dark-green leaf color in strawberry mutants but also provide potential genetic resources for cultivating strawberry varieties with enhanced photosynthetic capacity.

BACKGROUND: Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don] (syn. Prunus pseudocerasus Lindl), native to China, is an important fruiting cherry species belonging to the Rosaceae family. Fruit size is a key factor limiting the large-scale production of this crop. However, the regulatory mechanisms governing fruit size in Chinese cherry remain poorly understood. RESULTS: In this study, we analyzed comparative physiological characteristics and performed transcriptome sequencing to identify key genes regulating fruit size in Chinese cherry. The increase in fruit diameter and weight follows a typical double-sigmoid growth pattern. The final fruit size is attributed to both cell division and cell expansion, corresponding to Sigmoid I (SI) and Sigmoid II (SII), respectively. Auxin, gibberellin, cytokinin, and brassinosteroids showed a marked increase during the SI phase, followed by varying degrees of decrease during the slow-growth stage, and a slight increase during the SII phase. During SI phase, IAA, GA3, and ZR exhibited much higher levels or more rapid increases in large fruits (HF) compared to small fruits (PJHH), indicating their important roles in early fruit enlargement. Comparative transcriptomic analysis identified a total of 8,938 DEGs through pairwise comparisons across SI and SII phases between HF and PJHH. Gene Ontology (GO) enrichment analysis revealed that numerous genes associated with cell cycle and phytohormones, including auxin, gibberellin, and cytokinin, exhibited differential expression between large- and small-fruited landraces. Some candidate genes were validated by RT-qPCR analysis, including CpCDKB2;2, CpPAT14, CpRBR, CpGH3.1, CpARF6, CpIAA6like, CpYUCCA10, CpGA2oxlike, and CpARR5like, among others. CONCLUSIONS: These findings provide a theoretical foundation for the regulation of fruit size in Chinese cherry breeding. In the future, new Chinese cherry cultivars with larger fruits may be bred by overexpression genes that positively regulate fruit size or by knocking out genes that negatively regulate fruit size via transgenic or gene editing technologies.

Cherries are one of the economically important fruit crops in the Rosaceae family,Prunus genus.As the first fruits of the spring season in the northern hemisphere,their attractive appearance,intensely desirable tastes,high nutrients content,and consumer-friendly size captivate consumers worldwide.In the past 30 years,although cherry geneticists and breeders have greatly progressed in understanding the genetic and molecular basis underlying fruit quality,adaptation to climate change,and biotic and abiotic stress resistance,the utilization of cherry genomic data in genetics and molecular breeding has remained limited to date.Here,we thoroughly investigated recent discoveries in constructing genetic linkage maps,identifying quantitative trait loci(QTLs),genome-wide association studies(GWAS),and validating functional genes of edible cherries based on available de novo genomes and genome resequencing data of edible cherries.We further comprehensively demonstrated the genetic architecture of the main agronomic traits of edible cherries by methodically integrating QTLs,GWAS loci,and functional genes into the identical reference genome with improved annotations.These collective endeavors will offer new perspectives on the availability of sequence data and the construction of an interspecific pangenome of edible cherries,ultimately guiding cherry breeding strategies and genetic improvement programs,and facilitating the exploration of similar traits and breeding innovations across Prunus species.

Sugar, acid, and phenol are critical indicators for assessing the fruit quality to pear. In this study, 81 pear germplasm resources belonging to the malic acid type were analysed and evaluated. Notably, the ‘Guanguanli’ cultivar from the Dadu River exhibited high sugar content and low acidity levels while ‘Mozili’ and ‘Gedali’ cultivars contained rutin. Additionally, ‘Huangpixishali’ cultivar from Yalong and Anning Rivers also showed presence of rutin. Among these varieties, the lowest titratable acidity was observed in ‘Zhenbaili’ cultivar from the Min and Tuo Rivers with a value of 0.084 %. Furthermore, 'Machengtuoli' cultivar had a soluble solid content as high as 17.44 % in this region. The second-highest soluble solid content at 16.86 % was found in ‘Qingli’ cultivar from Yangtze River basin. The stone cell content was lowest (0.135 %) in ‘Huahongli’ variety originating from Yalong and Anning rivers.

As one of the most salt-sensitive crops, strawberry production is severely limited by salt stress. γ–aminobutyric acid (GABA) has been reported to play an important role in the immune response of plants. In this study, the physiological and transcriptomic changes in strawberry seedlings treated with GABA under salt stress were investigated to explore the effect of GABA on salt tolerance. The results showed that exogenous GABA maintained high osmolyte levels, increased antioxidant capacity, and decreased the ROS levels in strawberry leaves under salt stress; the MDA was reduced by 3.27–31.46

The cuticle layer serves as the first protective barrier against environmental biotic and abiotic stresses for plants. Although transcriptional and post-transcriptional regulation of cuticle biosynthesis genes has been extensively studied, the translational control remains poorly understood. The eukaryotic translation initiation factor (eIF3h) is a known regulator in protein translation. In this study, we generated stable transgenic strawberry (Fragaria vesca L.) plants overexpressing the eukaryotic translation initiation factor FveIF3h to investigate its role in cuticular wax biosynthesis. Overexpression (OE) lines exhibited enhanced vegetative growth but reduced chlorophyll content, alongside a significant decrease in leaf wax deposition and increased permeability. As a result, OE plants exhibited increased susceptibility to drought stresses. Quantitative proteomics revealed downregulated wax synthesis proteins, notably CER4/FAR3, which contains an upstream open reading frame (uORF) in its mRNA. A luciferase reporter assay confirmed FveIF3h represses CER4/FAR3 translation via its uORF. These findings uncover a novel translational regulatory mechanism in strawberry cuticular wax biosynthesis, highlighting FveIF3h as a potential target for enhancing crop resilience.

Proanthocyanidins (PAs), natural polyphenolic antioxidants, play a crucial role in various physiological processes in plants. This study aimed to investigate the impact of exogenous PAs on the postharvest fruit quality and resistance to gray mold in strawberry during storage. Postharvest strawberries were individually treated with 2, 5 and 10 mg L- 1 PAs solutions, and the related traits of quality and resistance were analyzed. The results showed that exogenous PAs could reduce water loss, natural decay incidence, severity of strawberry decay, as well as the in vitro lesion diameter and area of Botrytis cinerea growth. Among all the concentrations tested, 5 mg L- 1 showed the most inhibition effect with around a 70 % reduction in decay incidence, and a 28 % reduction in in vitro spot lesion area. Furthermore, strawberries treated with 5 mg L- 1 PAs had similar skin color variables, titratable acidity and anthocyanins content, but higher level of total soluble solids, total phenolics, total flavonoids, and endogenous PAs content. Moreover, the DPPH antioxidant activity was increased by 5 mg L- 1 PAs treatment, while no obvious change was found in FRAP. In vivo studies showed that the incidence of decay caused by B. cinerea infection was reduced by 53.7 %, with severity decreased to grade 2 in the fruit treated with 5 mg L- 1 PAs, which was significantly lower than that observed in the control group. Additionally, the content of salicylic acid (SA) at d 2 and 4 during storage was remarkably increased compared to the control. Furthermore, the expression levels of downstream genes including TGA (TGACG motif-binding factor) and pathogen related proteins (PR) were somewhat increased by PAs treatment. In summary, our results revealed that exogenous PAs enhanced resistance of strawberry to gray mold through both increasing endogenous non-enzymatic antioxidants, as well as inducing the SA signaling pathway.

This study investigated the efficacy of exogenous L-cysteine (L-Cys) and L-methionine (L-Met) in preserving postharvest quality and extending shelf life of strawberry cultivars 'Benihoppe' and 'Fenyu No.1'. Fruits were treated with varying concentrations (L-Cys at 0.01-0.2 % and L-Met at 0.5-100 mM) and stored under controlled conditions. Results showed that 0.1 % L-Cys and 50 mM L-Met optimally reduced weight loss by 16.3 % and 40.4 %, respectively, and decay incidence by 24.5 % and 35 % compared to controls. Both treatments maintained higher ascorbic acid (AsA) levels, with L-Met being more effective, while differentially modulating phenolic metabolism. L-Cys increased total phenolic content by up to 42 % but suppressed anthocyanins. Highperformance liquid chromatography (HPLC) analysis revealed cultivar-specific effects on organic acids: L-Cys increased citric acid by 23.5 % in 'Benihoppe', whereas both amino acids reduced it in 'Fenyu No.1'. Oxidative stress markers exhibited cultivar-dependent responses, with L-Cys and L-Met reducing malondialdehyde (MDA) by 18-27 % but sometimes increasing hydrogen peroxide (H2O2). L-Met preserved antioxidant enzyme activity, maintaining superoxide dismutase (SOD) 18-22 % higher than the control, while catalase (CAT) remained stable. These findings highlight the role of sulfur-containing amino acids (SAAs) in quality preservation, and supports L-Cys and L-Met as safe, effective alternatives to traditional preservatives for strawberries.

Shuguimei is a new early-ripening Chinese cherry [Cerasus pseudocerasus (Lindl.) G. Don] cultivar bred by Sichuan Agricultural University. The cultivar was derived from a cross between Hongfei and Nanzaohong in 2016. Through artificial cross pollination, approximately 200 hybrid seedlings flowered in 2019. The hybrid seedling HN880 was initially selected as an excellent individual in 2020 for its superior performance and high quality. The field trials were conducted at three sites in Sichuan Province (including Chengdu city, Suining city and Xichang city) from 2020 to 2023. It was approved as a new Chinese cherry cultivar by the Sichuan Provincial Non-major Crop Cultivar Certification Committee in January 2025, and named as Shuguimei. The young trees exhibit vigorous growth with a semiopen posture. The branchlets are grayish-brown, and the mature leaves are green and oblong-ovate with a long tail tip and a round base. The inflorescence typically consists of corymbs with 3-6 flowers. The flower buds are reddish, and the petals are white with a pink margin. Each flower has five round petals, one pistil, and 35-45 stamens with orange-yellow anthers. The fruit is primarily elliptical, with orangered peel. Its flesh is light yellow, juicy, and rich in flavor. Fruit mass ranges from 4.5 to 5.6 g. The average longitudinal diameter is 1.95 cm, the transverse diameter 2.11 cm, with a fruit shape index around 0.93. The average pit mass is 0.29 g. The fruit stalk is medium in length, averaging 2.33 cm. The total soluble solid (TSS) content ranges from 14.5% to 16.9%, and the titratable acid (TA) content is about 0.42%, giving a TSS/TA ratio of about 37.33. Glucose and fructose are the main components of soluble sugars, with contents of 392.48 and 301.67 g·kg-1, respectively. Malic acid is the predominant organic acid, at 84.59 g·kg-1. The overall eating quality is excellent. In Chengdu, Sichuan Province, the fruit development period lasts about 48-52 days, maturing in early to mid-April, which is 5-7 days earlier than its male parent, Hongfei. The vegetative growth period is about 310 days. Shuguimei bears fruit earlier and has good yield potential, with a small yield in the second year after planting and substantial fruiting in the fourth to fifth year. The average yield can reach 8400-8700 kg·hm-2. Young trees bear more fruit on middle and long branches, while adult trees predominantly bear fruit on boundary branches, short branches, and medium to long branches. The cultivar shows strong growth potential, adaptability, and resistance to diseases. It is suitable for planting in areas with ecological conditions similar to those found in the plains and hills of Sichuan Province. Shuguimei is best suited for planting in sandy loam with good drainage and deep soil layers. Spacing recommended is (2.5-3) m × (3.5-4) m. It is suitable to adopt open-center or central leader system.

BACKGROUND:Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don], an economically important fruit species native to southwestern China, plays a key role in regional agriculture. Organic acid composition is crucial for determining organoleptic quality of Chinese cherry, yet the underlying regulatory mechanisms remain unclear. RESULTS:In this study, we analyzed organic acid composition in mature fruits from 34 Chinese cherry accessions and tracked dynamic changes throughout fruit development in two landraces with distinct acidity levels (high and low), via HPLC and transcriptomics. Malic acid is the predominant organic acid component, which accounted for 73.66% of total acids. The high-acid landrace exhibited very rapid malate accumulation and relatively fast degradation, while the low-acid landrace showed minor changes in malate levels throughout fruit development. A total of 7,698 DEGs were clustered into six clusters, with DEGs from three clusters being significantly enriched in the "pyruvate metabolism" and "TCA cycle" pathways. Key genes involved in malate biosynthesis (cMDH, PEPC2) and transport (ALMT4, VHP) were up-regulated in the high-acid landrace, while NADP-ME, a gene associated with malate degradation, was down-regulated. Co-expressed network analysis highlighted strong correlations between key structural genes and transcription factors (MYB, ARF, AP2, and bHLH). Notably, CpODORANT1like and CpARF2Blike were identified as potential regulators of acidity, modulating NADP-ME and PEPC2 expression, respectively. These candidate genes were validated through an integrated analysis of phenotypic data and expression pattern of 34 genotypes. CONCLUSIONS:Our results suggest that malate accumulation in Chinese cherry is regulated at both the metabolic and vacuolar storage levels. This study deepens our understanding of the mechanisms regulating fruit acidity in Chinese cherry, which could inform future breeding efforts aimed at improving fruit flavor.

The phenylacetone pathway, which encompasses flavonoids, lignin, and other compounds, is of paramount importance in determining the quality of pear fruit. Nevertheless, the precise regulatory functions of R2R3-MYB transcription factors in the metabolic pathways that regulate pear color changes remain unclear. In this study, we isolated an R2R3-PbMYB5(PbMYB5) transcription factor from ‘Red Zaosu’ pears and demonstrated that it influenced the expression of several genes, including PbCAD1, PbF5H, PbLAR, PbANR, and PbUFGT. The overexpression of PbMYB5 resulted in a notable elevation in anthocyanin concentration within the pear epidermis. Further research has shown that PbMYB5 is able to bind to PbANS and also has interactions with PbbHLH3 and PbbHLH33.We proposed that PbMYB5 forms a complex with PbbHLH3, PbbHLH33, and PbWD40 to activate PbANS and promote anthocyanin accumulation. This study offers new insights into the regulation of various metabolic pathways that impact fruit coloration.

Chinese cherry [ Cerasus pseudocerasus (Lindl.) G.Don] (syn. Prunus pseudocerasus Lindl.) is an economically important fruit crop native to China. The fruits are prone to softening and rotting after harvest, which significantly limits their marketability and hinders its rapid development throughout China. The MADS-box gene family, particularly the SEP subfamily, plays a crucial role in governing fruit ripening and softening. However, the molecular mechanisms underlying fruit ripening and softening in Chinese cherry remains unclear. Herein, we identified 92 MADS genes from the Chinese cherry genome and analyzed their physicochemical characteristics, chromosomal localization, phylogeny, gene structures, covariance, and cis-acting elements. Many cis-elements in the promoters of CpMADSs are implicated in fruit development, ripening and stress response. Using comparative transcriptomics and RT-qPCR analysis, we identified a key gene, CpMADS47, as a positive regulator of cherry fruit ripening. CpMADS47 is localized in both the nucleus and cell membrane and shows highly expression in flowers and mature fruits. Transient overexpression of CpMADS47 in cherry fruit demonstrated its role in mediating fruit ripening and softening by promoting reduction in fruit firmness, anthocyanin accumulation, depolymerization of cell wall components, enhancement of cell wall degradation enzyme activity, and ABA biosynthesis. Conversely, silencing CpMADS47 generated the opposite effect. Yeast one-hybrid and dualluciferase assays revealed that the CpMADS47 targets the promoters of cell wall degrading genes ( CpPME3 and CpXTH31) and ABA signal transduction genes ( CpPP2C12 ), thereby activating their transcription and promoting cherry fruit ripening. In summary, this study enriches our understanding of the transcriptional regulation of fruit ripening and softening in Chinese cherry.

Chinese cherry [Cerasus pseudocerasus (Lindl.) G.Don] (syn. Prunus pseudocerasus Lindl.) is an economically important fruiting cherry species with a diverse range of attractive colors, spanning from the lightest yellow to the darkest black purple. However, the MYB transcription factors involved in anthocyanin biosynthesis underlying fruit color variation in Chinese cherry remain unknown. In this study, we characterized the R2R3-MYB gene family of Chinese cherry by genome-wide identification and compared it with those of 10 Rosaceae relatives and Arabidopsis thaliana. A total of 1490 R2R3-MYBs were classified into 43 subfamilies, which included 29 subfamilies containing both Rosaceae MYBs and AtMYBs. One subfamily (S45) contained only Rosaceae MYBs, while three subfamilies (S12, S75, and S77) contained only AtMYBs. The variation in gene numbers within identical subfamilies among different species and the absence of certain subfamilies in some species indicated the species-specific expansion within MYB gene family in Chinese cherry and its relatives. Segmental and tandem duplication events primarily contributed to the expansion of Chinese cherry R2R3-CpMYBs. The duplicated gene pairs underwent purifying selection during evolution after duplication events. Phylogenetic relationships and transcript profiling revealed that CpMYB10 and CpMYB4 are involved in the regulation of anthocyanin biosynthesis in Chinese cherry fruits. Expression patterns, transient overexpression and VIGS results confirmed that CpMYB10 promotes anthocyanin accumulation in the fruit skin, while CpMYB4 acts as a repressor, inhibiting anthocyanin biosynthesis of Chinese cherry. This study provides a comprehensive and systematic analysis of R2R3-MYB gene family in Chinese cherry and Rosaceae relatives, and identifies two regulators, CpMYB10 and CpMYB4, involved in anthocyanin biosynthesis in Chinese cherry. These results help to develop and utilize the potential functions of anthocyanins in Chinese cherry.

Citrus is one of the world's most economically important fruit crops cultivated by grafting. To support the growth of scion cultivars, rootstock is the primary source of resistance to various abiotic stresses. Herein, seedlings of two genotypes of Citrus junos Sieb. ex Tanaka (the novel rootstock 'Shuzhen No.1' and commonly used rootstock 'Ziyang Xiangcheng'), as well as three commonly used rootstocks including citrange (Citrus sinensis Osbeck. × Poncirus trifoliata Raf.), trifoliate orange (P. trifoliata), and red tangerine (Citrus tangerine Hort. Ex Tanaka), were used as testing materials. The seed characteristics were evaluated, and the rootstock seedlings were subjected to flooding, drought, alkaline, and freezing treatments. Over time, the contents of chlorophyll, soluble sugar, proline, malondialdehyde, and the activity of superoxide dismutase, peroxidase, and catalase in the leaves under different treatments were examined. Furthermore, five citrus varieties were grafted as scions onto one-year-old seedlings from the four rootstocks. Graft success, shoot growth, and leaf greenness were measured and compared. The physiological and biochemical changes in 'Shuzhen No.1' were found to be similar to those in 'Ziyang Xiangcheng'. 'Shuzhen No.1' exhibited greater tolerance to flooding, alkaline, and freezing stress compared to the other four widely used citrus rootstocks, as indicated by physiological and biochemical indexes and principal component analysis. Moreover, the five citrus varieties grafted onto 'Shuzhen No.1' demonstrated vigorous growth and tree vigor. These findings provide valuable insights for the application of 'Shuzhen No.1' and future research on citrus rootstock.