南京林业大学学报(自然科学版) ›› 2020, Vol. 44 ›› Issue (4): 12-20.doi: 10.3969/j.issn.1000-2006.202003047

所属专题: 木本花卉专题

• 专题报道 • 上一篇    下一篇

3个桂花品种花香组分动态特征及花被片结构解剖学观测

施婷婷1(), 杨秀莲1, 王良桂2()   

  1. 1.南京林业大学风景园林学院,江苏 南京 210037
    2.南京林业大学林学院,南方现代林业协同创新中心,江苏 南京 210037
  • 收稿日期:2020-03-15 修回日期:2020-04-24 出版日期:2020-07-22 发布日期:2020-08-13
  • 通讯作者: 王良桂
  • 作者简介:施婷婷(tingtingshi@njfu.edu.cn),助理研究员。
  • 基金资助:
    江苏省科技计划重点项目(BE20173751);江苏高校优势学科建设工程资助项目

Dynamic characteristics of floral components and anatomical observation of petals in three cultivars of Osmanthus fragrans

SHI Tingting1(), YANG Xiulian1, WANG Lianggui2()   

  1. 1.College of Landscape Architecture,Nanjing Forestry University,Nanjing 210037, China
    2.Co -Innovation Center for the Sustainable Forestry in Southern China, College of Forestry,Nanjing Forestry University, Nanjing 210037, China
  • Received:2020-03-15 Revised:2020-04-24 Online:2020-07-22 Published:2020-08-13
  • Contact: WANG Lianggui

摘要: 目的

桂花[Osmanthus fragrans (Thunb.Lour.]是我国著名的香花植物,对其花香组分动态特征及花被片结构解剖学观测的研究能够为桂花的进一步开发利用提供参考。

方法

选取‘日香桂’(‘Rixiang Gui’)、‘雨城丹桂’(‘Yucheng Dan’)和‘波叶银桂’(‘Boye Yin’)3个桂花品种,采用顶空固相微萃取(HS-SPME)与气相色谱?质谱联用(GC-MS)技术对其花香成分进行检测分析,并结合多元统计分析对3个桂花品种的花香进行评价。同时,利用扫描电镜和透射电镜观察比较这3个桂花品种的超微结构。

结果

3个桂花品种共鉴定出51种挥发性花香物质,均以萜烯类物质为主,其中芳樟醇及其氧化物、α-紫罗兰酮、β-紫罗兰酮及二氢-β-紫罗兰酮为主要花香物质,但相对含量存在差异。偏最小二乘法判别分析(PLS-DA)表明,3个不同桂花品种的花香存在差异,并通过变量重要性投影(VIP)值选出了10种关键的差异花香物质,包括丁酸乙酯、顺式-芳樟醇氧化物、反式-β-罗勒烯等。基于这10种关键差异花香物质聚类分析发现,不同的品种或花期对桂花花香都有影响,但主要还是取决于品种的不同。此外,花被片超微结构观察发现桂花花香成分的聚合体(嗜饿酸基质颗粒)在细胞质体中形成,然后溢出细胞壁,最后通过表皮细胞上丰富的褶皱结构向外释放花香。

结论

3个桂花品种具有相似的特征花香物质,也存在着差异花香物质,同时这些花香物质在3个不同桂花品种中迥异的含量分布,共同形成了不同桂花品种的特有花香。此外,3个桂花品种花被片表皮细胞的褶皱结构,以及嗜饿酸基质颗粒的差异,也可能是3个桂花品种花香差异的原因之一。

关键词: 桂花, 花香成分, 顶空固相微萃取, 气相色谱-质谱联用, 偏最小二乘法判别分析, 超微结构

Abstract: Objective

Osmanthus fragrans (Thunb.) Lour. is one of the ten traditional flowers in China and is well known for its fragrance. This study focused on the dynamic characteristics of the aromatic components and anatomical observation of the perianth in three cultivars of O. fragrans. The results could lay the foundation for further the development and utilization of O. fragrans.

Method

Three cultivars of O. fragrans (‘Rixiang Gui’, ‘Yucheng Dan’ and‘Boye Yin’) were sampled at four flowering stages:the Xiangyan stage, initial flowering stage, full flowering stage, and final flowering stage. Then, the aromatic components in the three cultivarswere detected and analyzed by headspace solid-phase microextraction and gas chromatography-mass spectrometry (GC-MS). Further, the differences in the aromatic components among the three cultivars were evaluated using the multivariate statistical analysis. In addition, the perianth microstructure was observed by scanning electron microscopy and transmission electron microscopy.

Result

The GC-MS analysis detected a total of 51 volatile aromatic components, most of which were terpenes. Among the three cultivars of O. fragrans, 29, 27 and 33 aromatic components were identified in the petals of ‘Rixiang Gui’, ‘Yucheng Dan’ and ‘Boye Yin’, respectively. According to the relative content of aromatic components, the main components in the three cultivars of O. fragrans included linalool, cis-linalool oxide, trans-linalool oxide, α-ionone, β-ionone, and 2H-β-ionone; in addition, some common aromatic substances, such as trans-β-ocimene, cis-β-ocimene, and γ?decalactone were identified. The differences in the relative content of aromatic components and the interaction of all aromatic components together resulted in the unique aroma of the different cultivars. For example, β?ionone was the main aromatic component in the petals of ‘Boye Yin’, but its relative content was lower in ‘Yucheng Dan’. Linalool and its oxides were the main aromatic components in the petals of ‘Rixiang Gui’ and ‘Yucheng Dan’, but not in the petals of ‘Boye Yin’. The results from the partial least squares-discriminate analysis showed different aromatic components in the three cultivars of O. fragrans. Moreover, 10 critical differential compounds were screened using variable importance in projection, namely, ethyl butanoate, cis-linaloloxide, trans-β-ocimene, 4-(2,6,6-trimethyl-cyclohex-1-enyl)-butan-2-ol, γ?decalactone, 3-hydroxy-2-butanone, (E)-2-hexenal, megastigma-4,6(E),8(Z)-triene, cis-β-ocimene, and β-ionone. The cluster analysis based on the relative content of the 10 key differential compounds showed that three flowering stages (the Xiangyan stage, initial flowering stage, and full flowering stage) of ‘Rixiang Gui’ (A1, A2, A3), ‘Yucheng Dan’ (B1, B2, B3), and ‘Boye Yin’ (C1, C2, C3) could be clustered together, respectively, implying that the three cultivars could be distinguished by the amounts of the 10 key aromatic substances that they possessed during these three stages. However, the final flowering stage of the three cultivars could be clustered together. This may have been because of the decreased content of volatile aromatic substances during the final flowering stage; the weakened ability of the flower to release aroma may have led to the lack of major differences in the fragrance of the cultivars. The results of the scanning electron microscopy and transmission electron microscopy revealed abundant fold structures on the cell surface of the petals. The fold structures in the petals of ‘Boye Yin’ and ‘Yucheng Dan’ were more regular than that in the petals of ‘Rixiang Gui’. The density of the structures differed among different cultivars; for example, it was higher in the petals of ‘Boye Yin’ than that in the petals of ‘Rixiang Gui’ and ‘Yucheng Dan’. In addition, we observed a large number of granular substances (osmiophilic matrix granules) attached inside the cells and on the cell surface in the petals of O. fragrans.These granules were highly volatile aggregates of aromatic substances. The density and quantity of granules in the petals of ‘Boye Yin’ and ‘Rixiang Gui’ were higher than those in the petals of ‘Yucheng Dan’. We speculated that there were no secretory structures on the surface of O. fragrans petals; instead, most cells in the petals had aromatic glands involved in the synthesis and secretion of aromatic substances. The whole petal was like a large aromatic gland where the aggregates of aromatic substances (osmiophilic matrix granules) formed in the cytoplasts, then overflowed from the cell walls, spilled out through the abundant fold structures in the epidermal cells, and quickly evaporated. We surmised that this was why O. fragrans was highly fragrant.

Conclusion

There were similar and differential aromatic substances among the three cultivars of O. fragrans, and the differing proportions of these aromatic substances led to the unique aroma of the three cultivars. Overall, the floral fragrance of O. fragrans mainly differed according to the cultivar but was also affected bythe flowering stages. In addition, the differences in the density of fold structures and the amount of aromatic substance (osmiophilic matrix granules) aggregated on the epidermal cells of the perianth in the three cultivars of O. fragrans may be reasons for the differences in fragrance.

Key words: Osmanthus fragrans (Thunb.) Lour., floral compounds, headspace solid-phase micro-extraction, gas chromatography-mass spectrometry (GC-MS), partial least squares-discriminate analysis(PLS?DA), microstructure

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