Reviews

• Research Advances in the Regulation of Aroma Biosynthesis in Horticultural Crops by Plant Hormones and Environmental Factors
• XU Hongpeng, LU Jinping, JIANG Xiaonan, XIE Weilin, LIU Zhirou, BAN Jiayi, XUE Bingbing, YE Ruoyu, ZHANG Kexin, XIONG Yuchen, CHEN Jiamin, SONG Yefan, YUAN Fubang, WANG Yiqiao, LIU Zhuowen, GAO Junping, LIANG Yue
• Acta Horticulturae Sinica. 2026, 53(2): 331-358. DOI:10.16420/j.issn.0513-353x.2025-1069
• Abstract ( 371 ) HTML ( 261 ) PDF (1605KB) ( 261 ) 　　　

• The aroma quality of horticultural crops is an important economic trait determined by volatile organic compounds（VOCs）. Its biosynthesis is coordinately regulated by internal regulatory networks and external environmental factors. Phytohormones including jasmonic acid，ethylene，and auxin form complex regulatory networks by activating transcription factors such as MYB and bHLH，and precisely regulate the biosynthesis of aroma substances（e.g.，terpenoids and phenylpropanoids）through signal cross-talk. Signaling molecules，such as calcium ions，hydrogen peroxide，and nitric oxide，participate in regulating the expression of aroma biosynthesis-related genes by mediating hormone signals and environmental stimuli. Environmental factors such as light and temperature not only independently regulate aroma biosynthesis in horticultural crops，but also exert synergistic effects through interactions between photoreceptors and temperature sensors. This review summarizes recent research progress on the regulation of aroma biosynthesis in horticultural crops by phytohormones，signaling molecules，and environmental factors，aiming to provide a theoretical reference for plant aroma research and the breeding of horticultural varieties with high aroma quality.

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• Molecular Insights into the Formation and Regulation of Floral Scent Traits in Ornamental Plants
• WANG Fang, FAN Yanping
• Acta Horticulturae Sinica. 2026, 53(2): 359-385. DOI:10.16420/j.issn.0513-353x.2025-0815
• Abstract ( 267 ) HTML ( 109 ) PDF (1775KB) ( 109 ) 　　　

• Floral scent serves as a crucial signal mediating interactions between plants，their environment，and other organisms. It is predominantly composed of diverse volatile organic compounds（VOC）emitted from floral tissues，including terpenoids，phenylpropanoids/benzenoids，and fatty acid derivatives. The biosynthesis of floral volatiles involves multiple metabolic pathways and exhibits pronounced spatiotemporal dynamics across different developmental stages and floral tissues. This process is coordinately regulated by key enzyme-encoding genes，transcription factors，hormonal signaling，and environmental cues. In ornamental plants where terpenoids dominate the floral bouquet，members of the terpene synthase（TPS）gene family，together with several quantitative trait loci（QTL），largely determine the diversity and specificity of floral scent composition. With the rapid advancement of multi-omics and molecular breeding technologies，transgenic approaches and genome editing tools，such as CRISPR/Cas9，have shown great potential for modifying floral scent traits. Concurrently，microbial“cell factory” systems offer promising strategies for the scalable and sustainable production of natural floral volatiles. This review provides a comprehensive overview of the major chemical constituents and metabolic pathways underlying floral scent in plants，as well as the spatiotemporal regulation of volatile emission and the associated key genes and regulatory networks. Finally，it further discusses recent advances and future prospects in the molecular breeding and industrial applications of floral scent. The review aims to offer a theoretical framework for understanding the molecular mechanisms of scent formation and to provide new perspectives for its application in ornamental plant improvement and related industries.

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• Research Progress on the Biological Functions and Biosynthetic Mechanisms of Floral Scent
• XIE Yuying, SHI Tingting, YANG Xiulian, WANG Lianggui, YUE Yuanzheng
• Acta Horticulturae Sinica. 2026, 53(2): 386-396. DOI:10.16420/j.issn.0513-353x.2025-0853
• Abstract ( 212 ) HTML ( 49 ) PDF (1428KB) ( 49 ) 　　　

• Floral scent serves multifaceted ecological and physiological roles in plant reproduction and defense mechanisms. It not only selectively attracts pollinators through specific volatile compounds and provides resistance against biotic stressors，but also participates in intracellular reactive oxygen species scavenging and signaling transduction，collectively forming a complex“plant-micropollinator-environment”interaction network. At the molecular level，the biosynthesis of floral scent is regulated through sophisticated hierarchical mechanisms，including epigenetic modifications such as DNA methylation and non-coding RNAs，coordinated regulation of structural genes by transcription factor families，as well as post-translational protein modifications including ubiquitination and histone modifications. These regulatory layers collectively ensure precise spatiotemporal control of floral scent production and stress-responsive emission. Research demonstrates that floral scent biosynthesis is intrinsically linked to plant senescence and stress adaptation processes，being modulated by hormonal signaling networks while exhibiting significant ecological adaptability and defensive functions under environmental challenges such as salt stress and herbivory.

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• Research Progress on MYB Transcription Factor Regulation of Aromatic Compound Synthesis in Horticultural Plants
• CHEN Yun, BAO Fei
• Acta Horticulturae Sinica. 2026, 53(2): 397-411. DOI:10.16420/j.issn.0513-353x.2025-0996
• Abstract ( 169 ) HTML ( 54 ) PDF (1545KB) ( 54 ) 　　　

• As one of the largest transcription factor families in plants，MYB transcription factors play a central role in regulating the biosynthesis of aromatic compounds in horticultural crops. Recent studies have clarified that MYB members precisely regulate the synthetic metabolism of key aromatic substances，including terpenoids，phenylpropanoids，and fatty acid derivatives，by directly binding to structural gene promoters or forming complexes through interactions with proteins such as bHLH and WD40. This review systematically summarizes the functions and mechanisms of MYBs in the aromatic synthesis regulatory network over the past decade，focusing on their regulatory pathways in model plants and major horticultural crops. It also proposes future directions for the regulation between environmental factors and MYB-mediated aroma synthesis.

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• Research Progress on Volatile Substances in Orchidaceae：From Synthetic Mechanisms to Evolutionary Drivers
• ZHAO Yuqing, TANG Feihong, ZHENG Shijie, GUAN Zeen, WU Jiankai, LIU Zhongjian, PENG Donghui, LAN Siren, ZHAO Kai, ZHOU Yuzhen
• Acta Horticulturae Sinica. 2026, 53(2): 412-436. DOI:10.16420/j.issn.0513-353x.2025-0911
• Abstract ( 244 ) HTML ( 59 ) PDF (5532KB) ( 59 ) 　　　

• This review systematically summarizes recent advances in the research on the patterns of manifestations，driving factors，and regulatory mechanisms underlying floral volatile substances variation in the family Orchidaceae. Groups such as Cymbidium，Phalaenopsis，and Dendrobium exhibit genus-level specificity differentiation in volatile substances. Terpenoid compounds constitute the characteristic volatile fragrance components of most current orchids，whereas certain “specialized” taxa produce distinctive odors dominated by ketones，sulfur-containing compounds，amines，and other uncommon constituents. Volatile substance variations of Intra-specific and hybrid orchids are reflected not only in the composition and relative abundance，but also in the diversity of emission rhythms，which are highly synchronized with pollinator activity patterns. From the perspective of influencing factors，genetic factors represent the fundamental determinants of volatile substances diversity in orchids. In recent years，a series of key genes involved in the biosynthesis of terpenoids，phenylpropanoids，and other volatile compounds（such as structural genes like TPS） have been obtained，and they are strongly influenced by developmental stages，diurnal changes and trait trade-off. Non-biological factors can also alter the release intensity and component ratio of volatile substances. The metabolism of the main volatile substances is mainly regulated by transcription，and forms a cellular activity pattern of storage-release or active transport. In addition，the adaptive evolutionary relationship among pollinators may be an important ecological driver of scent diversification. The olfactory preferences of different pollinator groups（such as moths，bees，and beetles，etc.） have promoted the evolution of species-specific floral scent signals，thereby contributing to reproductive isolation and species differentiation. However，there are still some deficiencies in current researches. For instance，the functions and genetic patterns of volatile substances in the flower parts of some orchidaceae plants remain unclear，the molecular regulatory networks synthesized by them have not been fully elucidated，and the mechanism of exogenous regulation of flower fragrance is not systematically studied. In the future，by integrating research methods from biology and ecology，multi-omics technology and gene editing technology，the molecular mechanisms of the synthesis and regulation of volatile substances in the flower parts of orchids can be deeply explored，revealing their diverse evolutionary driving forces，and providing theoretical basis and technical support for the targeted breeding of new varieties of aromatic orchids and the development of functional products.

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• A Review of Iris pallida Germplasm Resources and Volatile Components
• TIAN Min, DONG Yanmei, ZHENG Tao, LI Hui, XIA Fei, WANG Di, BAI Hongtong, ZENG Haitao, SHI Lei
• Acta Horticulturae Sinica. 2026, 53(2): 437-446. DOI:10.16420/j.issn.0513-353x.2025-1054
• Abstract ( 161 ) HTML ( 22 ) PDF (1611KB) ( 22 ) 　　　

• The rhizomes of Iris pallida Lam. are rich in unique aromatic compounds. After aging treatment，high-value essential oil with violet-like fragrance can be extracted from them. This paper provides a systematic review of the germplasm resources of I. pallida，the techniques for extracting its volatiles，major chemical components（particularly irone），as well as the research progress of these volatiles in fragrance blending，fragrance fixation and antibacterial activity. It also prospects the development future of the I. pallida industry, aiming to provide theoretical references for realizing the efficient utilization of its resources and promoting technological innovation and sustainable development of the entire industrial chain.

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• Advances in Floral Aroma Biosynthesis and Regulation in Tree Peony
• NIU Tongfei, YANG Di, MA Huili, GUO Lili, HOU Xiaogai
• Acta Horticulturae Sinica. 2026, 53(2): 447-466. DOI:10.16420/j.issn.0513-353x.2025-0961
• Abstract ( 165 ) HTML ( 29 ) PDF (1942KB) ( 29 ) 　　　

• Tree peony（Paeonia Sect. Moutan DC.）is highly valued for its ornamental qualities，including large flower size，bright colors，and diverse fragrance types. In recent years，analyzing the aroma components and breeding fragrant varieties have become key research foci. This paper systematically reviews the research progress on tree peony fragrance，primarily covering the collection methods of aroma components，the factors influencing aroma synthesis and release，and the biosynthetic pathways of key aroma compounds. Finally，perspectives on future research directions were offered，aiming to provide a theoretical reference for the breeding and industrial application of tree peony fragrance.

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• Research Progress on Floral Fragrance in Prunus mume
• YUE Zhiyi, LI Xin, WANG Haoning, ZHANG Qixiang, SUN Lidan
• Acta Horticulturae Sinica. 2026, 53(2): 467-480. DOI:10.16420/j.issn.0513-353x.2025-1117
• Abstract ( 173 ) HTML ( 23 ) PDF (2024KB) ( 23 ) 　　　

• The floral scent of Prunus mume is mainly composed of benzenoid and phenylpropanoid volatile organic compounds. The biosynthesis and emission of floral scent in P. mume exhibit pronounced spatial and temporal specificity and are also influenced by multiple factors，including light，temperature，and exogenous regulators. This review summarizes recent advances in research on P. mume floral scent，with a focus on the major scent components and their biosynthetic pathways，molecular regulatory mechanisms，and emission patterns. Future research directions are also discussed，with the aim of providing references for elucidating the formation mechanisms of floral scent traits in P. mume and for guiding the efficient breeding of new cultivars with novel fragrance characteristics.

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• Advances in the Biosynthetic Genes and Evolutionary Mechanisms of Floral Volatile Organic Compounds in Rosa hybrida
• FU Qi, SHANG Junzhong, PEI Wenwen, LIU Guoliang, JING Weikun, ZHANG Hao, JIAN Hongying, QIU Xianqin, TANG Kaixue, YAN Huijun
• Acta Horticulturae Sinica. 2026, 53(2): 481-495. DOI:10.16420/j.issn.0513-353x.2025-0957
• Abstract ( 170 ) HTML ( 31 ) PDF (2051KB) ( 31 ) 　　　

• Rosa hybrida is one of the most economically valuable species of cut flowers，garden，and potted plants worldwide，with fragrance being a critical trait that enhances its ornamental value. However，during selecting cultivars focused on achieving flower color diversity and extending vase life，floral fragrance has gradually diminished or disappeared in rose. A wide range of scent compounds have been identified in rose germplasm resources，whose biosynthesis is regulated by genetic background，domestication history，and environmental factors. Gene family expansion，allelic diversity，and copy number variation are key determinants of the diversity of rose floral scent compounds. This review systematically summarizes the typical compounds，biosynthetic pathways，regulatory mechanisms，and evolutionary history of scent compounds in roses. Furthermore，the potential applications of integrating pan-genomics with gene editing technologies for directed breeding in roses were discussed. This review is expected to provide a theoretical framework for the targeted regulation of scent traits and the development of new roses cultivars with diverse fragrance profiles.

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Research Papers

• Identification of Floral Fragrance Components and Analysis of Aroma Characteristics of Chrysanthemum × morifolium‘Lixiang’
• ZHANG Peng, YE Xinru, LI Hualong, CHEN Yuyuan, SUN Ming, TANG Yuchao
• Acta Horticulturae Sinica. 2026, 53(2): 496-512. DOI:10.16420/j.issn.0513-353x.2025-0494
• Abstract ( 199 ) HTML ( 47 ) PDF (4110KB) ( 47 ) 　　　

• In this study，Chrysanthemum × morifolium‘Lixiang’was used as the material，and the headspace adsorption（HSA）method combined with automatic thermal desorption-gas chromatography- mass spectrometry（ATD-GC-MS）was utilized to analyze the floral fragrance of‘Lixiang’flowers at bud stage，half-open stage，and peak flowering stage at 14：00，as well as at peak flowering stage at 6：00 and 22：00. The principal component analysis（PCA），hierarchical clustering analysis（HCA）and partial least squares discriminant analysis（PLS-DA）were employed to construct a discriminant model for the volatile organic compounds（VOCs）and to identify differential VOCs. Finally，the relative odor activity value（ROAV）was calculated to analyze the aroma characteristics. A total of 86 VOCs were detected across different flowering stages and time points，with 39 common to all. At 14：00 during the peak flowering stage，both the highest number of VOC types（68）and the highest emission rate（4 032.57 ng · g^-1 · h^-1）were observed. The 86 VOCs were classified into 4 categories，terpenes exhibited both the highest number and emission levels of VOCs at all sampling points，α-pinene was the most abundant VOC in the fragrance of‘Lixiang’. Using VIP scores and P values，a total of 24 differential volatiles were screened. ROAV analysis identified 4 key characteristic aroma components，ethyl isobutyrate provided the highest odor contribution value，imparting a characteristic fruity fragrance to‘Lixiang’flowers，α-pinene，propyl 2-methylpropanoate and (Z)-β-ocimene imparted resin/pine-like，fruity and terpene fragrance characteristics，respectively.

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• Identification of Aroma Components and Analysis of Expression Characteristics of Terpene Synthase Genes in Chrysanthemum Floral Scent Mutants
• HUANG Yawen, HUANG Hongfeng, WANG Zhiling, CHEN Siyu, ZHANG Shiqi, HONG Bo, GU Zhaoyu
• Acta Horticulturae Sinica. 2026, 53(2): 513-524. DOI:10.16420/j.issn.0513-353x.2025-0870
• Abstract ( 195 ) HTML ( 45 ) PDF (1814KB) ( 45 ) 　　　

• Aroma is one of the key quality traits of chrysanthemum. To investigate the differential accumulation of volatile compounds and their biosynthetic mechanisms in chrysanthemum，this study used the chrysanthemum cultivar‘Pink Yan’and its mutant as materials. Techniques including headspace solid-phase microextraction combined with gas chromatography-mass spectrometry（HS-GC-MS），transcriptome sequencing，and quantitative real-time PCR（RT-qPCR）were employed to systematically analyze differences in volatile components and screen related terpene synthase genes. The research showed 56 common components were detected in the volatile substances of the two，mainly terpenes，and 6 and 9 unique components were identified in‘Pink Yan’and mutant. Integrated transcriptome and RT-qPCR analyses revealed six differentially expressed terpene synthase genes，three of which were up-regulated and three down-regulated. Among them，Terpene synthase 7 gene（c25536.graph_c0）showed the highest expression level and significant differential expression，suggesting it may be a key gene regulating the differential accumulation of terpenoid compounds.

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• Cloning and Functional Analysis of LiMYB4 in Regulating Terpenoid Biosynthesis in Lilium‘Siberia’
• SHEN Yan, XIA Ziyi, LENG Pingsheng, MA Bo, HU Zenghui
• Acta Horticulturae Sinica. 2026, 53(2): 525-537. DOI:10.16420/j.issn.0513-353x.2025-0946
• Abstract ( 185 ) HTML ( 42 ) PDF (4652KB) ( 42 ) 　　　

• Terpenoids constitute the primary volatile components of lily floral scent，and MYB transcription factors are crucial regulators of terpenoid biosynthesis. In this study，Lilium‘Siberia’was used as the experimental material for cloning and characterizing LiMYB4，including analysis of spatiotemporal expression patterns，protein sequence homology，and phylogenetic relationships. In addition，transient silencing and overexpression assays were employed in the petals to investigate the role of LiMYB4 in terpenoid biosynthesis. The results showed that LiMYB4 contains a 738 bp ORF encoding 245 amino acids. The predicted LiMYB4 possesses two conserved MYB domain repeats and was thus classified as a member of the R2R3-MYB subfamily. The phylogenetic analysis showed the highest similarity（71.26%）with AeMYB4 from Amana edulis. The spatial expression profiling demonstrated significantly higher transcript level of LiMYB4 in perianths compared with roots，stems，or leaves. During floral development LiMYB4 expression first decreased and then increased，which was inversely correlated with terpenoid emission dynamics. The functional validation showed that transient silencing of LiMYB4 increased the emission of linalool and ocimene in petals. Conversely，LiMYB4 overexpression markedly reduced the emission of these volatiles. Further analysis of the terpene backbone biosynthesis genes revealed that the transcript levels of LiDXR，LiGPPS，LiOcS，and LiLiS were significantly upregulated in LiMYB4-silenced petals，but downregulated in LiMYB4-overexpressing petals. Collectively，these results demonstrate that LiMYB4 acts as a negative regulator of terpenoid biosynthesis in Lilium‘Siberia’by directly or indirectly suppressing the expression of key genes in the terpenoid biosynthesis pathway.

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• Integrated Metabolome and Transcriptome Analysis of Floral Scent in Maxillaria tenuifolia
• WEI Yonglu, YE Guangying, GAO Jie, JIN Jianpeng, LU Chuqiao, LI Jie, XIE Qie, GOU Yajun, ZHU Genfa, YANG Fengxi
• Acta Horticulturae Sinica. 2026, 53(2): 538-556. DOI:10.16420/j.issn.0513-353x.2025-0861
• Abstract ( 198 ) HTML ( 40 ) PDF (6025KB) ( 40 ) 　　　

• This study systematically investigated the floral scent composition and metabolic characteristics of four floral organs（sepals，petals，lip，and column）in Maxillaria tenuifolia. Volatile organic compounds from each organ were analyzed using gas chromatography-mass spectrometry （GC-MS），and transcriptome data were integrated to identify candidate genes involved in the biosynthesis of key aroma constituents. The results revealed significant differences in the variety and relative content of scent compounds among the floral organs. Among the 31 aroma compounds identified in total，the sepals exhibited the highest diversity（30 compounds）and the highest total volatile content（96.55 μg · g^-1 FW）. Based on relative odor activity value（ROAV）analysis，δ-decalactone，massoia lactone，and δ-cadinene were determined as the main contributors to the characteristic aroma，imparting a distinctive scent profile blending coconut and herbal notes. Transcriptome analysis indicated that differentially expressed genes associated with floral scent biosynthesis were predominantly enriched in pathways such as terpenoid，phenylpropanoid，flavonoid，and fatty acid metabolism. By integrating metabolic and transcriptomic data，5 candidate regulatory genes（FAD，HMGR，MYB，TPS，WRKY）were further screened，which are likely to play key roles in the regulatory network of scent biosynthesis in M. tenuifolia.

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• Elucidation of Floral Scent Formation in Phalaenopsis-Type Dendrobium Hybrids by Integrated Metabolome and Transcriptome Analysis
• LI Chonghui, HONG Xiaoyu, LU Shunjiao, LIAO Yi, YIN Junmei
• Acta Horticulturae Sinica. 2026, 53(2): 557-573. DOI:10.16420/j.issn.0513-353x.2025-1050
• Abstract ( 197 ) HTML ( 60 ) PDF (5902KB) ( 60 ) 　　　

• Phalaenopsis-Type Dendrobium hybrids（Den-Phals）have high ornamental value，but most cultivars lack floral fragrance. Using the aromatic cultivar D.‘Udomsri Beauty’（HZZ）and the non-aromatic cultivar D. Yaya Victoria（MN）as experimental materials，metabolomics analysis and transcriptome sequencing were conducted. Weighted Gene Co-expression Network Analysis and integrated analysis of both omics datasets were performed to screen differentially expressed genes, and real-time quantitative PCR（RT-qPCR）was used to validate the expression patterns of key genes. The results showed that among the identified volatile metabolites，terpenoids were the most abundant in both variety（159 kinds）and content. Relative odor activity value（rOAV）analysis identified compounds such as linalool，3,6-nonadienal，and 2-pentylfuran，were described as having floral，green，and fruity scent characteristics-as significant contributors to the floral fragrance of HZZ. The fragrant HZZ specifically accumulated monoterpenes like linalool and theaspirane during full-bloom stage, whereas the non-fragrant MN primarily accumulated sesquiterpenes. Specific monoterpenes，rather than total terpene content，are closely associated with the pleasant fragrance of Den-Phals. The formation of fragrance in Den-Phals was accompanied by coordinated upregulation of genes in the terpenoid biosynthesis pathway. Further analysis identified 11 core candidate genes（e.g.，genes encoding terpene synthase，S-linalool synthase，sesquiterpene synthase，etc.）with very low expression in MN，while their expression in HZZ significantly increased during flower development，peaking at full-bloom stage，and showed a significant positive correlation with the accumulation of key terpenoid metabolites. RT-qPCR validation confirmed consistency with the transcriptome data. The specific high expression of key terpenoid synthesis candidate genes during the late developmental stages of the fragrant cultivar is an important molecular mechanism underlying fragrance formation in Den-Phals.

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• Effects of Exogenous Melatonin on Rose Fragrance
• XU Yong, YANG Yang, WANG Ruotong, MAO Yiru, FENG Liguo
• Acta Horticulturae Sinica. 2026, 53(2): 574-584. DOI:10.16420/j.issn.0513-353x.2025-1059
• Abstract ( 161 ) HTML ( 46 ) PDF (2051KB) ( 46 ) 　　　

• Using two-year-old Rosa rugosa‘Fenghua’plants，we investigated the effects of foliar-applied melatonin（0.1，0.3 and 0.5 mmol · L^-1）on floral volatile organic compound（VOC）emission. Treatment with 0.3 or 0.5 mmol · L^-1 melatonin significantly increased flower diameter by 21.3% and 22.2%，respectively. Application of 0.3 mmol · L^-1 melatonin markedly enhanced the contents of key aroma compounds：at the bud stage，geraniol，citronellol，and methyleugenol increased by 100.0%，39.1% and 52.2%，respectively；at full bloom，citronellol and the monoterpene esters citronellyl acetate and geranyl acetate rose by 50.7%，102.2% and 108.2%，respectively. Concurrently，2-phenylethanol and its derivative phenylethyl acetate increased by 71.9% and 164.8%. These results indicated a nonlinear dose-response relationship，where VOC levels peaked at 0.3 mmol · L^-1 melatonin and declined at higher concentrations. qRT-PCR analysis showed that 0.3 mmol · L^-1 melatonin significantly upregulated four terpenoid biosynthesis-related genes and the key 2-phenylethanol synthesis gene RrAADC（aromatic amino acid decarboxylase）. Virus-induced gene silencing（VIGS）of RrAADC confirmed its central role：melatonin application in silenced petals restored both RrAADC expression and 2-phenylethanol accumulation to wild-type levels，demonstrating that RrAADC is a critical target gene in melatonin-mediated regulation of 2-phenylethanol biosynthesis.

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• Analysis of Flower Fragrance Components and Study on Fragrance Release Parts in Hybrid Offspring of Rosa gigantea
• LIU Tinghan, ZHANG Yifan, CHEN Yunyi, ZHOU Lijun, LIU Yuchen, WU Sihui, LUO Le, YU Chao
• Acta Horticulturae Sinica. 2026, 53(2): 585-597. DOI:10.16420/j.issn.0513-353x.2025-0919
• Abstract ( 172 ) HTML ( 31 ) PDF (4953KB) ( 31 ) 　　　

• Known as the“Queen of Flowers”，Rosa spp. boasts significant ornamental and commercial value attributed to its floral fragrance. Currently，most products derived from rose scent are dominated by the rose fragrance type sourced from R. damascena，while research on other fragrance types remains limited. R. gigantea，a species endemic to China，exhibits a distinctive aroma. Therefore，twelve progenies obtained from the hybridization of R. chinensis‘Old Blush’and R. gigantea were employed as experimental materials. Through integrated analyses of volatile metabolomics and histochemical staining techniques， the composition，genetic characteristics，and fragrance-releasing tissues of floral scent components in these progenies were systematically elucidated. The results demonstrated that a total of 39 primary aromatic compounds were identified in the progenies，predominantly terpenoids and phenylpropanoids. Among these，the differential content of eugenol served as the key criterion for progeny classification，displaying the genetic characteristics of a qualitative trait. Notably，neither the type nor the content of aromatic substances could effectively distinguish between double-petaled and single-petaled groups. Histochemical staining revealed that both the adaxial and abaxial epidermis of petals contained osmophore structures enriched with granular precursor substances，which function as the primary sites for fragrance emission. The progenies inherited the parental traits in terms of osmophore morphology and distribution，whereas the lipid release pattern exhibited paternal specificity.

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• Screening and Validation of Reference Genes for qRT-PCR Analysis of Genes Related to Floral Scent Biosynthesis in Camellia japonica
• CHEN Yiquan, FAN Ronghui, LIN Bing, CHEN Yan, WU Jianshe, ZHONG Huaiqin
• Acta Horticulturae Sinica. 2026, 53(2): 598-612. DOI:10.16420/j.issn.0513-353x.2025-0772
• Abstract ( 198 ) HTML ( 49 ) PDF (3865KB) ( 49 ) 　　　

• To study the expression patterns of genes related to floral scent biosynthesis in Camellia japonica and screen for stably expressed reference genes. Quantitative real-time PCR（qRT-PCR）technology was used to detect the expression levels of 10 candidate reference genes（α-TUB，CYP，PP2A，ACTIN1，ACTIN2，GAPDH，UBQ，AQP，UBC，and HIS）in different tissues，flowering stages，cultivars and mixed samples. The stability of internal reference genes was comprehensively evaluated and identified using four algorithms：geNorm，NormFinder，BestKeeper，and RefFinder. The results showed that the primer specificity of the 10 candidate reference genes was good，and all of them had the performance as reference genes. PP2A and UBC can be used for analyzing gene expression at different flowering stages. The most ideal reference genes for analyzing gene expression in different tissues and fragrance cultivars were identified as PP2A and ACTIN1. PP2A can be stably expressed in different tissues，flowering stages，fragrance cultivars and mixed samples. Nine floral scent-related target genes were amplified by qRT-PCR，and PP2A is the optimal reference gene for studying the expression of floral scent-related genes in Camellia japonica. However，when the traditional housekeeping gene GAPDH was used as the reference gene，significant deviations were observed in the expression patterns of the linalool/nerolidol synthase gene（CaLIS/NES1）and the phenylacetaldehyde reductase gene（CaPAR）.

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• Screening of ABCG Genes Related to the Transport of Volatile Compounds in Chimonanthus praecox
• LIU Yuting, FU Xuemei, HU Yihang, CHEN Longqing
• Acta Horticulturae Sinica. 2026, 53(2): 613-634. DOI:10.16420/j.issn.0513-353x.2025-0926
• Abstract ( 173 ) HTML ( 29 ) PDF (7638KB) ( 29 ) 　　　

• Fourty-four CpABCG genes were identified in Chimonanthus praecox through bioinformatic analysis. Characterization of the ABCG subfamily and its potential role in floral scent emission was preliminarily investigated. All CpABCG proteins contain transmembrane domains（TMD）and nucleotide-binding domains（NBD）；The analysis of conserved motif revealed that Motif 1，3，and 4 are characteristic of the ABCG family. The collinearity analysis indicated closer phylogenetic relationship between CpABCG and PmABCG；The promoters of CpABCG genes contain cis-elements responsive to light，plant development，abiotic stress，and phytohormones；The results of qRT-PCR indicated that three genes CpABCG1.2，CpABCG9.1 and CpABCG25.2 are highly expressed in flowers，and their expression patterns are closely related to the release pattern of floral fragrance in C. praecox；After the treatment with exogenous floral scent inhibitors，the total floral emission decreased significantly，while the endogenous volatile substances increased correspondingly；Based on expression profiling，CpABCG1.2 and CpABCG9.1 were proposed to play key roles in transmembrane transport of floral volatile compounds in C. praecox.

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