Tea Flowers Research Articles

Volatile Composition and Aroma Description of Tea (Camellia sinensis) Flowers from Albino Cultivars

Volatiles are important quality components in tea (Camellia sinensis) flowers. Albino tea plants are mutant tea plants with diverse abnormal metabolisms. However, whether the metabolisms of volatiles in tea flowers from albino cultivars are abnormal remains unclear. In this study, headspace solid-phase microextraction coupled to gas chromatography-mass spectrometry and aroma evaluation were conducted to investigate the volatile composition and aroma of tea flowers from three albino cultivars (i.e., Baiye No.1, Huangjinya, and Yujinxiang) and one non-albino cultivar (i.e., Jiukeng). The results indicated that tea flowers shared the majority of volatiles but their relative abundances were different. Twelve differential compounds were screened out by partial least squares discriminant analysis. Linalool was the one with the highest relative abundance in three out of the four tea flowers, while acetophenone was the one with the highest relative abundance in tea flowers from Huangjinya. Aroma evaluation indicated that tea flowers from Huangjinya smelt sweetest among them. Partial least squares regression analysis revealed that acetophenone and (R)-1-phenylethanol were positively associated with the sweet smell, while methyl salicylate, 2-heptanol, (E)-2-hexenal, nonanal, and 2-pentanol were positively associated with the green smell. The results enhance our understanding of the volatiles and aroma of tea flowers from albino cultivars.

The Blooming Flowers of Tea Plants and Their Honey

Tea (Camellia sinensis L.) leaves provide beneficial effects for human health, and the functions of the main components of their leaves have been widely studied. Recently several physiological functions of tea flowers have been reported, and the flowers have received attention as a natural healthy material for food and cosmetics. It is not well known that the fragrant tea flowers have sweet nectar. The tea nectar may be attractive to honeybees. However, the honey from tea flowers has not been studied, even though in autumn, many tea fields are filled with blooming flowers in almost all the tea production areas around the world. In addition, honey from tea flowers has not been seen on the market. It was unclear whether tea honey is available. The study used honeybees (Apis mellifera L.) and took a small amount of honey from the blooming flowers of tea plants, which contained theanine (L-glutamic acid γ-ethylamide), a specific amino acid of tea plants. The theanine concentration of the nectar of the tea flowers exceeded that of the honey. Theanine is an extremely rare amino acid in nature, and it has psychoactive properties. This result is evidence that this honey is derived from tea flowers. Furthermore, the concentration of caffeine in the tea nectar might affect the honeybee’s brain to improve memory, suggesting that honeybees prefer to collect the nectar and produce honey. This study aims to prove that tea flower honey can be harvested and further proposes a unique tea sightseeing where visitors can taste the honey of tea flowers in the gorgeous scenery and fragrance of flower tea gardens.

Teh herbal terstandar simplisia bunga gemitir (Tagetes erecta Linn.) sebagai kandidat antioksidan baru

Empirically, gemitir flower (Tagetes erecta Linn.) has been used for generations as an alternative to treat whooping cough and eye pain medication. Gemitir flower is potential as an antioxidant because it contains secondary metabolites of phenolic groups, flavonoids, and alkaloids that have been shown to have antioxidant activity. As a pharmaceutical products, medicinal plants must be guaranteed quality and safety. This study aims to determine the suitability of the simplicia quality of gemitir flowers by standardization based on Indonesian Herbal Pharmacopoeia and Indonesian Materia Medica, and also to determine the antioxidant potential of standardized herbal teas of gemitir flowers. This first step of this research were standardization of gemitir flower simplicia based on specific and non-specific parameters, followed by making standardized herbal tea of gemitir flower. Antioxidant activity test was carried out on tea preparations using the DPPH method. The results showed that the simplicia of gemitir flower met all the standard parameters of specific and non-specific standardization with an ash content value of 3,47%, acid insoluble ash content of 0,11%, water soluble extract content of 24,86%, ethanol soluble extract content of 21,67%, drying shrinkage content of 9,33%, moisture content of 9,23% and foreign organic matter of 0,3%. Standardized herbal tea simplicia gemitir flower was able to inhibit 50% of DPPH free radicals at a volume of 33,87 µL. Based on the results, it can be concluded that the empirical use of gemitir flower tea potential as a natural antioxidant.

Quality components identification and formation analysis of tea (Camellia sinensis L.) flower beverages from three cultivars

The tea flower has a wide utilization value and contains tea polyphenols, amino acids and other substances, which can be processed into beverages. However, the whole regulatory network of the quality components in tea flowers is still unclear, and the processing techniques of tea flower beverages needs to be optimized. Here, the dynamic changes of main components in tea flowers at three developmental stages from three cultivars were basically grasped. Besides, the biosynthetic regulatory network of main components in tea flowers was preliminarily constructed. The expressions and possible interaction effects of 144 differentially expressed genes (DEGs) screened out during the development of tea flowers showed that these genes might regulate the components contents in tea flowers and provide a molecular mechanism for the synthesis of the components. In addition, the sensory evaluation and main components determination of tea flower beverages made through different processing techniques were carried out to explore the effects of processing techniques on the quality of tea flower beverages. It was showed that the tea flowers at the white bud stage and the drying technique were more suitable for making tea flower beverages with high quality.

Chemical composition and anti-cholesterol activity of tea (Camellia sinensis) flowers from albino cultivars.

Albino tea cultivars are mutant tea plants with altered metabolisms. Current studies focus on the leaves while little is known about the flowers. To evaluate tea flowers from different albino cultivars, the chemical composition and anti-cholesterol activity of tea flowers from three albino cultivars (i.e., Baiye No.1, Huangjinya, and Yujinxiang) were compared. According to the results, tea flowers from Yujinxiang had more amino acids but less polyphenols than tea flowers from the other two albino cultivars. A reduced content of procyanidins and a high chakasaponins/floratheasaponins ratio were characteristics of tea flowers from Yujinxiang. In vitro anti-cholesterol activity assays revealed that tea flowers from Yujinxiang exhibited stronger activity in decreasing the micellar cholesterol solubility, but not in cholesterol esterase inhibition and bile salt binding. It was noteworthy that there were no specific differences on the chemical composition and anti-cholesterol activity between tea flowers from albino cultivars and from Jiukeng (a non-albino cultivar). These results increase our knowledges on tea flowers from different albino cultivars and help food manufacturers in the cultivar selection of tea flowers for use.

Effects of Different Drying Methods on the Quality of Bletilla striata Scented Tea.

Flower tea is widely loved as a drink, especially for the beautiful and rich flowers of the orchid family, and the drying method for different flowers is also unique. GC-MS is widely used to study volatile substances to determine the quality of flower teas. The findings show that the freeze-drying method can retain the original aroma and flavor of Bletilla striata has the highest sensory evaluation score, with the key flavor substances ethyl caproate and N-heptanal containing 1.14% and 6.28%, respectively, and their ROAV values reaching 54.46 and 100.00. Additionally, the freeze-drying method can well retain flavonoids, polysaccharides, and phenolic components, while providing better antioxidant and antibacterial properties. The stove-drying method would make Bletilla striata slightly burnt and less flavorful and efficacious than freeze-drying; the air-drying method is difficult to retain the special odor and fragrance of Bletilla striata flowers and has the lowest sensory evaluation score, with the presence of volatile components with irritating and unpleasant odors such as pyrazine and 2-pentylfuran, while not showing better efficacy. In addition, steam fixation would destroy the morphology and flavor of Bletilla striata, lose polysaccharide and phenolic components, and reduce the efficacy of Bletilla striata scented tea, but could retain the flavonoid components well. In summary, direct freeze-drying without steam fixation is the best process for drying Bletilla striata scented tea, stove-drying without steam fixation is more economical and convenient in actual production and application, steam fixation and air-drying are not suitable as drying processes for Bletilla striata scented tea. This study analyzed the quality of Bletilla striata scented tea under different drying methods, promoted the further processing of Bletilla striata scented tea, and provided a reference for the comprehensive utilization of Bletilla striata scented tea.

Three new yeast species from flowers of Camellia sinensis var. assamica collected in Northern Thailand and their tannin tolerance characterization.

Our recent research study focused on Miang fermentation revealed that tannin-tolerant yeasts and bacteria play vital roles in the Miang production process. A high proportion of yeast species are associated with plants, insects, or both, and nectar is one of the unexplored sources of yeast biodiversity. Therefore, this study aimed to isolate and identify yeasts of tea flowers of Camellia sinensis var. assamica and to investigate their tannin tolerance, which is a property essential to Miang production processes. A total of 82 yeasts were recovered from a total of 53 flower samples in Northern Thailand. It was found that two and eight yeast strains were distinct from all other known species within the genera Metschnikowia and Wickerhamiella, respectively. These yeast strains were described as three new species, namely, Metschnikowia lannaensis, Wickerhamiella camelliae, and W. thailandensis. The identification of these species was based on phenotypic (morphological, biochemical, and physiological characteristics) and phylogenetic analyses of a combination of the internal transcribed spacer (ITS) regions and the D1/D2 domains of the large subunit (LSU) ribosomal RNA gene. The yeast diversity in tea flowers acquired from Chiang Mai, Lampang, and Nan provinces had a positive correlation with those acquired from Phayao, Chiang Rai, and Phrae, respectively. Wickerhamiella azyma, Candida leandrae, and W. thailandensis were the species uniquely found in tea flowers collected from Nan and Phrae, Chiang Mai, and Lampang provinces, respectively. Some of the tannin-tolerant and/or tannase-producing yeasts were associated with yeasts in the commercial Miang process and those found during Miang production, i.e., C. tropicalis, Hyphopichia burtonii, Meyerozyma caribbica, Pichia manshurica, C. orthopsilosis, Cyberlindnera fabianii, Hanseniaspora uvarum, and Wickerhamomyces anomalus. In conclusion, these studies suggest that floral nectar could support the formation of yeast communities that are beneficial for Miang production.

Sensorium

Sensorium

Butylene Glycol Used as a Sustainable Solvent for Extracting Bioactive Compounds from Camellia sinensis Flowers with Ultrasound-Assisted Extraction.

The research aims to assess the yield of bioactive compounds and their antioxidant activities obtained from tea flowers using an ultrasound-assisted extraction method with butylene glycol (BG-UAE) through Box-Behnken design. It investigates the bioactive compounds including the total phenolic content (TPC), total flavonoid content (TFC), and total tannin content (TTC) and analyzes their antioxidant activities, bioactive compound composition by liquid chromatography triple quadrupole tandem mass spectrometry, and their cellular activities via UAE and maceration using BG or ethanol as the solvent. Under optimal conditions, the values of the TPC, TFC, TTC, 1,1-diphenyl-2-picrylhydrazil radical scavenging assay, 2,2'-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid radical scavenging assay, and ferric reducing antioxidant power assay (FRAP) of the BG-UAE extract were 54.00 ± 1.19 mg GAE/g sample, 291.47 ± 3.34 mg QE/g sample, 65.37 ± 1.78 mg TAE/g sample, 106.45 ± 1.21 mg TEAC/g sample, 163.58 ± 2.76 mg TEAC/g sample, and 121.31 ± 4.75 mg FeSO4/g sample, respectively. Except for FRAP, BG-UAE exhibited the highest values in all parameters compared to the other extraction methods. Catechins and caffeine were predominantly detected in tea flower extracts through UAE with BG and ethanol (EtOH-UAE). BG-UAE exhibited greater cell viability and cellular antioxidant activity than EtOH-UAE. The researcher expects that this research will contribute to the emergence of a green extraction technique that will offer larger functional components with economic and environmental benefits and minimal chemicals and energy use.

A Comparative Study of Convolutional Neural Network Model for Chinese Flower Tea Classification

While flower teas are well-known for their health benefit, little did people know, there are several types of flower tea, and each type has its health benefit. Due to the unavailability of an automated system for classifying Chinese flower tea at the meantime, we then decided to apply the Convolutional Neural Network to help the wider community or flower tea plantation owners to classify flower tea more quickly, accurately, and automated. The purpose of this research is to classify flower tea based on their type by using CNN algorithm. In this research, we used multiple CNN models to find the most suitable architecture. The CNN models compared are ResNet50, SqueezeNet, AlexNet, and ResNet18. The result indicates AlexNet to achieve the highest accuracy of 97.92%

차박물관의 교육프로그램 활성화 방안 연구

The Hoann Museum of Tea Ware is a culture and art complex of tea culture that has provided appreciation of works related with tea and education programs including traditional etiquette, tea ceremony(茶禮) and practice of tea manufacture since its opening on December 15th of 2007 by remodeling the closed school. The Hoann Museum of Tea Ware is optimally qualified for a open culture and art complex to learn culture and art and traditional etiquette. Especially, it creates an environment for appreciation and research of antiques and discussing a history and culture of tea for students studying a tea master and tea and people interested in pottery. This study researched and analyzed the programs including experience of Deokeum Flower Tea, tea ceremony and tea confectionery from ‘Humanities on the Road’ program in the Hoann Museum of Tea Ware, and suggested the plan to design experience programs of five senses in preparation for the post-COVID 19 era. It specifically diversifies participants and consolidates online education, securing experience and public concern.

Comparison of the Formulation, Stability and Biological Effects of Hydrophilic Extracts from Black Elder Flowers (Sambucus nigra L.).

Elderflower preparations have long been used to treat colds and flu, but their use is undeservedly reduced, and only dried flower teas, less often ethanolic extracts, can be purchased in pharmacies. In the case of homemade teas, the medicinal plant material is extracted with hot water for a relatively short time, thus only a small part of the active substances is extracted. The industrially produced ethanolic extract is rich in active substances, but its use is limited since ethanol in many countries is undesirable and unsuitable for children and geriatric patients. Therefore, the aim of this work was to produce extracts from elder flowers using water as extractant and a mixture of water + polyethylene glycol (PEG) 20%, to compare their chemical composition and stability, and to study the ability to neutralize reactive oxygen species (ROS) and to sustain the viability of C6 glial cells under oxidative stress conditions. The ethanolic extract was used as a standard. Thus, the extract with PEG contained more than two times higher amount of total phenolics (PC) than the aqueous one, and the stability at 6-8 °C was comparable to the stability of ethanolic extract. All three extracts showed an antioxidant effect in a concentration-dependent manner in vitro. However, only the PEG containing extract (at 20-40 µg/mL PC) was the most effective in reducing the intracellular level of ROS and sustaining the viability of glial cells. The results suggest that the co-solvent PEG increases the yield of phenolics in the extract, prolongs the stability, and enhances positive biological effects.

Geniposidic Acid from Eucommia ulmoides Oliver Staminate Flower Tea Mitigates Cellular Oxidative Stress via Activating AKT/NRF2 Signaling

Eucommia ulmoides Oliver staminate flower (ESF) tea enjoys a good reputation in folk medicine and displays multiple bioactivities, such as antioxidant and antifatigue properties. However, the underlying biological mechanisms remain largely unknown. In this study, we aimed to investigate whether ESF tea can mitigate cellular oxidative stress. Crude ethyl alcohol extract and its three subfractions prepared by sequential extraction with chloroform, n-butyl alcohol and residual water were prepared from ESF tea. The results of antioxidant activity tests in vitro manifested n-butyl alcohol fraction (n-BUF) showed the strongest antioxidant capacity (DPPH: IC50 = 24.45 ± 0.74 μg/mL, ABTS: IC50 = 17.25 ± 0.04 μg/mL). Moreover, all subfractions of ESF tea, especially the n-BUF, exhibited an obvious capacity to scavenge the reactive oxygen species (ROS) and stimulate the NRF2 antioxidative response in human keratinocytes HaCaT treated by H2O2. Using ultra-high-performance liquid chromatography, we identified geniposidic acid (GPA) as the most abundant component in ESF tea extract. Furthermore, it was found that GPA relieved oxidative stress in H2O2-induced HaCaT cells by activating the Akt/Nrf2/OGG1 pathway. Our findings indicated that ESF tea may be a source of natural antioxidants to protect against skin cell oxidative damage and deserves further development and utilization.

Transcriptome Analysis Revealing the Interaction of Abscisic Acid and Cell Wall Modifications during the Flower Opening and Closing Process of Nymphaea lotus.

As a tropical flower, Nymphaea lotus is a typical night-blooming waterlily used in water gardening. Its petals are rich in aromatic substances that can be used to extract essential oils and as flower tea. However, the short life of the flower seriously affects the development of its cut flowers. At present, neither the mechanism behind the night-opening waterlily flower's opening and closing nor the difference between day-opening and night-opening waterlily flowers' opening and closing mechanisms are clear. In this study, endogenous hormone contents of closed (CP) and open (OP) petals were measured, and transcriptome analysis of CP and OP petals was carried out to determine the signal transduction pathway and metabolic pathway that affect flower opening and closing. ABA and cell wall modification were selected as the most significant factors regulating flowering. We used qRT-PCR to identify the genes involved in the regulation of flower opening in waterlilies. Finally, by comparing the related pathways with those of the diurnal type, the obvious difference between them was found to be their hormonal regulation pathways. In conclusion, the endogenous ABA hormone may interact with the cell wall modification pathway to induce the flowering of N. lotus. Our data provide a new direction for the discovery of key factors regulating the flower opening and closing of N. lotus and provide basic theoretical guidance for future horticultural applications.

The combination tea of corn silk (Zea mays L.) and rosella flowers (Hibiscus sabdariffa L.): Antioxidant levels using different drying methods

Corn silk and rosella flowers are plants whose utilization can still be developed, especially in the food sector. The secondary metabolites found in both plants serve as a source of natural antioxidants to combat free radicals. This study aims to examine the effect of variations in drying methods on the antioxidant activity content of a combination tea of corn silk and rosella flower. Antioxidant level test using the DPPH method. Analysis of antioxidant data in the form of determining the IC50 value using probit linear regression analysis. The study results show that drying using the oven method has an IC50 of 83 ppm while drying in the sun has an IC50 of 121 ppm. Research findings indicate high antioxidant levels in a combination of corn silk and rosella flower tea through oven drying and moderate antioxidants in direct drying in the sun.

Antioxidant Properties of TeNan Herbal Tea Formulation “Telang (Clitoria ternatea) and Pineapple (Ananas comosus)”

Herbal teas was are widely consumed by people around the world have high antioxidant activities. The flavor and color combination of specific teas enriches the aroma and appearance of the tea, producing a tea with fresh color and tastier flavor. This study determines the antioxidant activity of telang flower tea (Clitoria ternatea), pineapple tea (Ananas comosus), and the formula of the combination of telang flower tea and pineapple tea called TeNan. The antioxidant activities of herbal teas were measured by 2,2 Diphenyl-1-picrylhydrazyl (DPPH), Hydrogen Peroxide (H2O2), 2,2′-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) (ABTS), Ferric Reducing Antioxidant Power (FRAP) assay. The total phenol measurement used Gallic Acid Equivalent (GAE), while the flavonoid content measurement used Quercetin Equivalent (QE). The DPPH scavenging activities of telang flower tea, pineapple tea, and TeNan tea (IC50: 17.07%, 11.81%, and 22.22%), H2O2 scavenging activities (IC50: 26.62%, 41.81%, and 96.22%), ABTS-reducing activities (IC50: 2.51%, 3.39%, and 1.02%), and FRAP activities (IC50: 5.56%, 18.67%, and 7.48%). The total phenolic and flavonoid contents of TeNan tea were lower (9.44 μg GAE/100%; 3.46 μg QAE/100% sample concentration) than those of telang flower tea (16.20 μg GAE/100%; 4.88 μg QAE/100% sample concentration) but higher than those of pineapple tea (0.82 μg GAE/100%; 0.17 μg QAE/100% sample concentration). TeNan tea has the higher in ABTS and FRAP activities but lower in H2O2 and DPPH scavenging activities compared to telang flower tea and pineapple tea. In summary, telang tea has stronger antioxidant activity compared to pineapple and TeNan tea in FRAP and H2O2 assays.

Effects of different drying methods on chemical compositions, antioxidant activity and anti-α-glucosidase activity of Coreopsis tinctoria flower tea

Coreopsis tinctoria (CT) flower is widely consumed as flower tea with many good healthcare benefits in China, and room drying is the most common drying method of CT, while many rapid and controllable modern instrument drying methods have been used for the drying of flowers teas. In the present study, effects of drying methods on chemical components, antioxidant activity and anti-α-glucosidase activity of CT have been compared to search for proper drying methods. In the results, drying methods have significant effects on the chemical composition, antioxidant activity and anti-α-glucosidase activity of CT. Vacuum drying at 50 °C, hot air drying at 30 °C and hot air drying at 50 °C are the top three drying methods to produce dried CT of high quality, and hot air drying at 30 °C is more energy-efficient and time-saving. Our results provide some new choices for CT in the future.

Elucidation of Bioactive compounds in flower extracts of Camellia sinensis by HPLC-DAD-MS/MS and their inhibitory effects on replicative bacterial DNA polymerases

Camellia sinensis L. (C. sinensis) is an economically valuable crop whose leaves are used to produce tea. Tea flowers extracts (TFE) have been tested for their DNA polymerase inhibitory effect experimentally and in silico. Antioxidant capacities of TFE were determined by their DPPH radical scavenging activities (RSA), total phenolic acid, and flavonoid contents. While methanol extract and its fractions, except the aqueous fraction, showed strong inhibition on Gram (-) DNA polymerase DnaE, ethyl acetate, and butanol fractions showed strong inhibition on Gram (+) DNA polymerase PolC. The fractions had varying degrees of inhibition in tested microorganisms, except Enterococcus faecalis. Bacillus subtilis was the most inhibited microorganism. The binding energies of compounds for both polymerases varied between − 5.5 kcal/mol (polC) and − 9.7 kcal/mol (DnaE). Some compounds especially interact with the catalytic aspartic acid amino acids (D973, D975, and D1098) of polC. The ethyl acetate fraction had the best DPPH RSA and the highest total phenolic content. According to HPLC-DAD-MS/MS analysis, tea catechins corresponded to 58.1% of all phenolics, which comprised 17.9% of the methanol extract. All these results might support the hypothesis of the use of TFE for a potential candidate as a functional food and beverage.

Integrating metabolite and transcriptome analysis revealed the different mechanisms of characteristic compound biosynthesis and transcriptional regulation in tea flowers.

The flowers of tea plants (Camellia sinensis), as well as tea leaves, contain abundant secondary metabolites and are big potential resources for the extraction of bioactive compounds or preparation of functional foods. However, little is known about the biosynthesis and transcriptional regulation mechanisms of those metabolites in tea flowers, such as terpenoid, flavonol, catechins, caffeine, and theanine. This study finely integrated target and nontarget metabolism analyses to explore the metabolic feature of developing tea flowers. Tea flowers accumulated more abundant terpenoid compounds than young leaves. The transcriptome data of developing flowers and leaves showed that a higher expression level of later genes of terpenoid biosynthesis pathway, such as Terpene synthases gene family, in tea flowers was the candidate reason of the more abundant terpenoid compounds than in tea leaves. Differently, even though flavonol and catechin profiling between tea flowers and leaves was similar, the gene family members of flavonoid biosynthesis were selectively expressed by tea flowers and tea leaves. Transcriptome and phylogenetic analyses indicated that the regulatory mechanism of flavonol biosynthesis was perhaps different between tea flowers and leaves. However, the regulatory mechanism of catechin biosynthesis was perhaps similar between tea flowers and leaves. This study not only provides a global vision of metabolism and transcriptome in tea flowers but also uncovered the different mechanisms of biosynthesis and transcriptional regulation of those important compounds.

Heterologous Expression and Characterization of Tea (Camellia sinensis) Polyamine Oxidase Homologs and Their Involvement in Stresses.

Polyamine oxidase (PAO) is a key enzyme maintaining polyamine homeostasis, which affects plant physiological activities. Until now, the gene members and function of PAOs in tea (Camellia sinenesis) have not been fully identified. Here, through the expression in Escherichia coli and Nicotiana benthamiana, we identified six genes annotated as CsPAO in tea genome and transcriptome and determined their enzyme reaction modes and gene expression profiles in tea cultivar 'Yinghong 9'. We found that CsPAO1,2,3 could catalyze spermine, thermospermine, and norspermidine, and CsPAO2,3 could catalyze spermidine in the back-conversion mode, which indicated that the precursor of γ-aminobutyric acid might originate from the oxidation of putrescin but not spermidine. We further investigated the changes of CsPAO activity with temperature and pH and their stability. Kinetic parameters suggested that CsPAO2 was the major PAO modifying polyamine composition in tea, and it could be inactivated by β-hydroxyethylhydrazine and aminoguanidine. Putrescine content and CsPAO2 expression were high in tea flowers. CsPAO2 responded to wound, drought, and salt stress; CsPAO1 might be the main member responding to cold stress; anoxia induced CsPAO3. We conclude that in terms of phylogenetic tree, enzyme characteristics, and expression profile, CsPAO2 might be the dominant CsPAO in the polyamine degradation pathway.