Subtropical Plant Science

Effects of Wuyi Charcoal Baking Process on the Volatile Components of Rougui Oolong Tea

HONG Cui-yun, LIN Ting-hao, GAO Jian-she, LIN Xi, WANG Guo-ying, ZHENG Ming-fen

2021, 50(06): 421-429. DOI: 10.3969/j.issn.1009-7791.2021.06.001

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Based on head-space solid phase microextraction / gas chromatography-mass spectrometry (HS-SPME/ GC-MS), oolong tea made from the fresh leaves of a predominant cultivar of Wuyi rock tea, Camellia sinensis ‘Rougui’, was chosen to investigate the effects of Wuyi charcoal baking process on the volatile components of Rougui oolong tea. A total of 443 volatile metabolites were identified, including 96 heterocyclic compounds, 81 ester compounds, 31 terpenoids compounds, 42 aromatics compounds, 55 ketone compounds, 24 hydrocarbons compounds, 35 alcohol compounds, 24 aldehyde compounds, 15 phenol compounds, 14 amine compounds, 10 acid compounds, 5 nitrogen compounds, 3 sulfur compounds and others. According to these 443 metabolites, both principal component analysis (PCA) and hierarchical clustering analysis (HCA) were demonstrated, which indicated that baking process was a key factor affecting the content of volatile components in oolong tea. With the increasing of charcoal baking degree, the contents of most volatile components in different substance classification increased significantly, and the represented components were the products with the baked aroma such as pyrazines, furfural derivatives and furan, which were generated by chemical reaction under thermal treatments like Maillard; Meanwhile, some substances with rich content and special floral and fruit aroma in oolong tea like geraniol, trans-nerolidol, phytol, α-farnesene and indole reduced significantly. The relative content of most volatile components increased significantly with the increasing of the charcoal baking degree, still cannot mean that the increasing in the total amount of aromatic substances in tea. Our research illustrated that the accumulation of aroma substances in oolong tea during the refined baking process mainly comes from the Maillard reaction under thermal treatments, and non-enzymatic degradation and oxidation like glycosides hydrolysis.

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Effects of Two Withering Methods on Metabolites and Quality during Withering Process of White Tea Based

YUE Wen-jie,

2021, 50(06): 430-438. DOI: 10.3969/j.issn.1009-7791.2021.06.002

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Based on metabolomics technology, the effects of different withering technologies on the metabolites and quality of white tea withering were compared. The results showed that the response of different metabolites to the two withering processes was different, reflecting three kinds of changes: the first type of metabolites was less affected by the withering process, such as caffeine, EGC and 2'-hydroxydihydrodaidzein; the second type of metabolites showed accelerated conversion rate under air conditioner withering, but had little effect on the final dry tea content, such as EGCG, theasinensin A, and strictinin; and the third type of metabolites was greatly affected by the withering time, such as theogallin and quinic acid. There were different effects on the quality of white tea by two withering processes. Under natural withering the contents of flavonoids (alcohols), glycosides, catechin polymers, etc. were higher, and the contents of these substances increased in the middle and late stages of withering; under air conditioner withering the content of phenolic acid and theanine was higher, and these substances decreased sharply in the latter stage of natural withering. The withering time was an important factor for the difference in the content of metabolites between the two withering processes.

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Effect of Blue Light Stress on Free Amino Acids of Anoectochilus roxburghii

WANG Chi, LIU Hui, WU Wen-xi, CHU Ke-dan, ZHAO Feng

2021, 50(06): 439-446. DOI: 10.3969/j.issn.1009-7791.2021.06.003

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Anoectochilus roxburghii was used as the test material, and the white light with an optical density of 30 μmol·m–2·s–1 was supplemented with three intensities of 60 μmol·m–2·s–1, 120 μmol·m–2·s–1 and 180 μmol·m–2·s–1 blue light stress for 56 days. Aminoquinoline-N-hydroxysuccinyl carbamate (AQC) pre-column derivatization combined with ultra performance liquid chromatography-tandem mass spectrometry was used to determine the content of free amino acids in order to clarify the response characteristics of the free amino acid components for blue stress. A total of 22 amino acids were detected stably. Threonine, Alanine, Glutamine, Valine, Sarcosine, Histidine, Asparagine and Tyrosine were the characteristic amino acids in A. roxburghii. The total amount of free amino acids increased first and then decreased with the extension of the stress time, and the content was the highest on the 14th day. The comprehensive results showed that blue light stress for 14 days could promote the synthesis of a variety of free amino acids in A. roxburghii, and the effect was best when supplemented with 180 μmol·m–2·s–1 intensity of blue light.

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Accumulation Mechanism of Volatile Components and Distillation Techniques of Flowers at Different

KONG Fan, HAO Qing, LIU Zheng-an, SHU Qing-yan

2021, 50(06): 447-453. DOI: 10.3969/j.issn.1009-7791.2021.06.004

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In this study, the orthogonal experimental design was used to explore the volatile components accumulation mechanism and distillation techniques in Paeonia ostii petals, namely three developmental stages including big bell-like stage (S1), round peach stage (S2) and bud-flaw stage (S3), solid-liquid ratio (1:1, 1:2 and 1:3) and distillation time (1 h, 2 h and 3 h). The volatile component was analyzed using gas chromatography-mass spectrometry (GC-MS) technology. The results showed that the kinds and content of volatile component in P. ostii petals at various developmental stages and using different distillation techniques were significantly different. A total of 145 volatile components were detected in 9 treatments, including alcohols, terpenes, aldehydes, esters, alkenes and other kinds of substances. The highest number of compounds (96) at S1 was obtained, among which other kinds of substances was abundant, while, alkanes were the major components of petals at both stages of S2 and S3. From the perspective of distillation techniques within the same developmental stages, the kinds and contents of volatile components were greatly affected by solid-liquid ratio and distillation time. The best distillation techniques was obtained for petals for 1 h distillation and the solid-liquid ratio of 1:1, 1:3 and 1:2 at S1, S2 and S3, respectively. This study laid a foundation for the multi-exploitation and utilization of P. ostii petals.

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Characterization and Influence Factors of Post-harvest Volatile Organic Compounds in Liquidambar

GAO Yan-fang,

2021, 50(06): 454-460. DOI: 10.3969/j.issn.1009-7791.2021.06.005

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Gas chromatography-mass spectrometry (GC/MS) was used to analyze the volatile components of Liquidambar formosana leaves under different developmental stages, drying time, storage mode and extraction temperature to reveal the numbers of volatile organic compounds released from L. formosana leaves and the pattern of growth and decline of volatiles under different post-harvest treatments. The results were as follows: (1) The terpenes released from L. formosana leaves mainly contain α-pinene, β-pinene, β-watercressene and limonene. (2) Young leaves had a higher variety of volatile components than that of mature leaves with camphene, β-terpinene and basilene only present in young leaves, while 3-carene and γ-pinene only present in mature leaves. (3) Drying time had a strong influence on the volatile compounds of L. formosana leaves, and the varieties of volatile compounds showed a gradual decrease with the extension of drying time. The majority terpenoids could be detected at different drying times and were therefore relatively stable. (4) Storage at –5 ℃ and 17 ℃ retained more volatile compounds, room temperature storage lost more compounds, but major terpenes could be detected under different storage condition. (5) High temperature extraction at 90 ℃ yielded more volatile compounds, but the terpenoids obtained at 70 ℃ extraction were relatively high. Room temperature extraction yielded the least variety of compounds but better reflected the real situation of aromatic substance volatilization from L. formosana leaves under practical landscape application. The results of this study provided a reference for post-harvest treatment and high-value resource utilization of L. formosana leaves.

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Effect of Protease Inhibitor on Freezing Tolerance of Hydrated Lettuce Seeds

BAO Hong-yan, YU Ying, DENG Jia-bao, LIU Bao-lin, HAN Ying-ying

2021, 50(06): 461-470. DOI: 10.3969/j.issn.1009-7791.2021.06.006

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Lactuca sativa seeds were selected as test materials, and exogenous protease inhibitor 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) was added to soak the seeds. The effects of DTNB on seed germination rate and physiological activity at low temperature were analyzed by programmed cooling. The results showed that the lethal temperature of lettuce seeds was –20 ℃ at low temperature. Exogenous DTNB 2 mmol·L–1 had the highest germination rate, that is, it had a significant protective effect on seed activity. At this concentration, the Superoxide dismutase (SOD) activity in seeds was 1.38 times higher than that in the control, and the hydroxyl radical scavenging ability was 1.17 times higher than that in the control. Compared with the control, two proteins, 11 S globulin seed storage protein Jug r4 (XP_023733339.1) and 11 S globulin seed storage protein 2 (XP_023769779.1), belonging to globulin family, were expressed after 2 mmol·L–1 DTNB imbibing, which could improve the freezing resistance of the seeds. SDS-PAGE experiment showed that seeds accumulated small molecular globulin polypeptides at low temperature, which had a chilling effect on the seeds. In conclusion, seeds had a certain freezing tolerance under low temperature. Exogenous addition of 2 mmol·L–1 DTNB could improve the germination rate, physiological activity, antifreeze protein generation, and accumulation of globulin polypeptides with smaller molecular weight of hydrated lettuce seeds, so as to improve the freezing resistance of seeds.

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Photosynthetic and Physiological Characteristics of Camellia perpetua under Different Light Intensities

YANG Yun-yuan, DENG Zheng, HUANG Yong-fang, LÜ Ming-tao, GONG Yong-jun

2021, 50(06): 471-477. DOI: 10.3969/j.issn.1009-7791.2021.06.007

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In order to explore the photosynthetic and physiological characteristics of Camellia perpetua under different light intensities, two-year-old C. perpetua cuttings were used as the research object, and four light intensities, including 10% light, 20% light, 40% light and full light, were set. The photosynthetic and physiological indexes were measured after 45 days of plant adaptation. The results showed that the photosynthetic rate (Pn) and stomatal conductance (Gs) were the highest in 10% light treatment, there was no significant difference between 20% light and 40% light treatment, but significantly higher than that in full light treatment. The intercellular CO2 concentration (Ci) and transpiration rate (Tr) of full light treatment were significantly higher than those of the other three treatments. There was no significant difference between 20% light treatment and 10% light treatment in Ci, but significantly lower than 40% light treatment. There was no significant difference between 20% light and 40% light, but significantly higher than 10% light in Tr. Contents of chlorophyll a, chlorophyll b and the total amount of chlorophyll were the highest under 40% light, which was significantly higher than those of other treatments. The protein content and peroxidase (POD) activity were the highest under 10% light. There was significant difference among the treatments in protein content, and the POD activity under full light was significantly lower than those of other treatments. Soluble sugar content, superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were the highest in full light and the lowest in 10% light. C. perpetua was more suitable for growing in shady and low light environment, which was conducive to photosynthesis, growth and development of plants. High intensity light environment would inhibit the photosynthetic physiology of C. perpetua in varying degrees.

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Flower Bud Differentiation and Endogenous Hormones Changes of Camellia oleifera

LI Meng-nan, DAI Qiu-yue, HUANG Yong-fang, YANG Yun-yuan, DENG Zheng

2021, 50(06): 478-484. DOI: 10.3969/j.issn.1009-7791.2021.06.008

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In order to explore the relationship between endogenous hormones and flowering process of Camellia oleifera, changes of endogenous hormone contents during flower bud differentiation were studied in four C. oleifera clone. Combined with the dynamic observation of C. oleifera flower formation and the morphological observation of paraffin sections in flower bud, the contents of zeatin nucleoside (ZR), abscisic acid (ABA), auxin (IAA) and gibberellin (GA) in Camellia flower bud were determined by enzyme-linked immunosorbent assay. Camellia flower bud differentiation process passed through the pre-differentiation stage (10 d), sepals formation stage (20 d), petal formation stage (30 d), pistil and stamens formation stage (20 d), ovary and florist formation stage (10 d), and pistil and stamens maturation stage (20 d) during 3—4 months. The time of flower bud differentiation was slightly different in different C. oleifera clones. ZR content in Camellia flower bud was relatively low with 5.102—16.412 ng·g–1 FW, but ABA content was relatively high with 76.815—137.648 ng·g–1 FW. Among them, the ZR, ABA content changes of ‘Yuehua 5’ and ‘Xianglin 8’ were similar, and the content changes of ‘Cenruan 3’ and ‘Cenruan 2’ were similar. The content of IAA was relatively high with 49.072—135.622 ng·g–1 FW, they all showed the changing trend of rising slowly, then decreasing and recovering. The GA content was relatively low with 5.616—13.720 ng·g–1 FW. Among them, the trend of IAA, GA content of different Camellia clones were consistent, but the trend of ZR, ABA content was different. ZR was conducive to the formation of flower organs; high concentration of IAA promoted flower bud differentiation, low concentration of IAA favored flowering; IAA and ABA had antagonistic effects obviously; GA inhibited flower bud differentiation.

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Status and Development Countermeasures of Soil and Water Conservation Pasture Resources in Garze

SONG Si-meng,

2021, 50(06): 485-494. DOI: 10.3969/j.issn.1009-7791.2021.06.009

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Garze Prefecture is an important ecological protection area in the Yangtze River Basin and a key construction area for ecological animal husbandry in Northwest Sichuan. Its soil and water conservation pasture resources composition and current status are of great significance to the development of grassland ecological economy in the region. Based on library references, surveys, and field work, species and their distribution of the soil and water conservation pasture resources in Garze Prefecture were investigated. The areal types of the soil and water conservation pasture were counted, and the floristic characteristics were analyzed as well. Results showed that totally 120 species of soil and water conservation pasture belonged to 28 genera in 11 families were found in Garze Prefecture. There were 4 dominant families such as Gramineae, Polygonaceae, Compositae, Leguminosae, and 3 dominant genera such as Polygonum, Artemisia, Festuca in Garze Prefecture. The soil and water conservation pasture resources occupied 6 areal types, most of which were distributed in temperate and pan tropic zone (71.43%). The temperate ingredients accounted for the largest proportion (46.43%), followed by pan tropical ingredients (25.00%). The spatial distribution was extremely uneven, with the most species in the vertical direction with the elevation?of 2000—3500 m, and in the horizontal direction the highest in the east and west alpine canyon.

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New Records of Plants from Guangdong ProvinceⅡ

DAI Jing-min, HUANG Yan-shuang,

2021, 50(06): 495-499. DOI: 10.3969/j.issn.1009-7791.2021.06.010

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Five species, Tropidia nipponica Masam., Commelina bicolor D. Q. Wang & M. E. Cheng, Ranunculus ternatus Thunb., Sedum stellariifolium Franch., Angelica morii Hayata, were reported as new records in Guangdong province, China. All of them were discovered in Danxiashan National Nature Reserve. The discovery of these new records not only enriched the germplasm resources of Guangdong province, but also had instructive significance for the study on the florogenesis of Mt. Danxia.

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New Geographic Distribution Records of Four Plant Species in Fujian

AN Chang, ZHOU Fu-xian, CHEN Shan-si, HUANG Ze-hao, FAN Shi-ming

2021, 50(06): 500-503. DOI: 10.3969/j.issn.1009-7791.2021.06.011

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In the process of the fourth Chinese materia medica resources survey, the authors found four new records of plant distribution of Fujian Province from Wuyishan, Nanjing, Jiangle, Youxi: Dendrolycopodium vertical (L. B. Zhang) L. B. Zhang & X. M. Zhou, Utricularia smithiana Wight, Trichosanthes hylonoma Hand.-Mazz. and Disporum sessile var. intermedium Y. H. Tseng & C. T. Chao. The specimens were deposited in the herbarium of Fujian University of Traditional Chinese Medicine (FJTCM).

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Research Progress of Maillard Reaction and Control Methods in Fruit and Vegetable Products

YU Wen, YE Qiu-ping, SHEN Qing-yu

2021, 50(06): 504-510. DOI: 10.3969/j.issn.1009-7791.2021.06.012

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Maillard reaction is a non enzymatic browning reaction commonly existing in the processing and storage of fruit and vegetable products. Its reaction mechanism is complex, which will cause browning, destroy the sensory quality of products, reduce the edible value, produce toxic and harmful substances and endanger human health. This paper summarized the process, influencing factors and inhibition methods of Maillard reaction in fruit and vegetable products, and discussed the problems existing in the current research, in order to provide reference for the control of Maillard reaction in fruit and vegetable products.

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