玉兰肉质外种皮挥发性成分与功能的初步研究

Preliminary Study of Volatile Components and Function of Sarcotesta in Magnolia denudata Desr.

以玉兰(Magnolia denudata Desr.)发育成熟的种子为材料,采用水蒸气蒸馏法和GC-MS技术对其肉质外种皮化学成分的种类和含量进行了分析研究,并就玉兰肉质外种皮对其种子吸水和失水的影响以及化感作用进行比较研究,以探讨其相应的生态学和生物学功能。结果表明:(1)玉兰肉质外种皮占整个完整种子重量的48.25%,有无肉质外种皮对其种子自身吸水没有明显影响,但在失水过程中有肉质外种皮的种子失水较慢,具有一定的保水作用。(2)玉兰种子肉质外种皮中萜烯类和醇类的种类较多,分别有12种和11种;但酮类和酯类的相对含量较高,分别为32.84%和18.03%,其中含量较多的成分依次是甲基庚烯酮(31.95%)、乙酸丁酯(17.69%)、对伞花烃(13.64%)和芳樟醇(6.61%)。(3)玉兰肉质外种皮浸提液对豌豆、白菜种子萌发具有明显的抑制作用,且随着浸提液浓度增加,豌豆种子发芽率由86.7%下降为6.0%,白菜种子发芽率由28.0%下降为0。研究推测,玉兰种子的肉质外种皮在功能上可能是一种类似肉质果果肉的结构,具有丰富的化学成分,不仅可以吸引鸟类传播其种子,也具有一定的化感作用。

With Magnolia denudata Desr.mature seeds as material,we analyzed the volatile components type and content of the sarcotesta by steam distillation and gas chromatography-mass spectrometry.To discussion the ecology and biology function,we has carried comparative study of sarcotesta effect on seed water absorption and loss and the influence on seed germination.The results show that：（1）the sarcotesta accounted for 48.25% of the whole complete seed weight.With/without sarcotesta of M.denudata on the seed water absorption and loss was observed show that the presence of sarcotesta has no significant impact on seed water absorption,but can decrease the water loss rate,indicating it has certain water conservation function.（2）The main types of volatile constituents are terpenes （12） and alcohols （11）,but the highest relative content of the components is ketones （32.84%） and the second is esters （18.03%）,which include methyl heptenone （31.95%）,butyl acetate （17.69%）,p-cymene （13.64%） and linalool （6.61%）.（3）By investigating the influence of sarcotesta leaching solution on peas and cabbage seed germination,it can be confirmed that the sarcotesta of M.denudata has obvious inhibitory effect.With the increase of concentration of leaching solution,pea seed germination rate reduced from 86.7% to 6.0% and cabbage seed germination rate from 28.0% to zero.We speculate that the sarcotesta of M.denudata in function is a kind of similar structure to pulp of fleshy fruit,which has the rich chemical compositions and plays an important role in its seed dispersal.It not only can attract birds spread their seeds,also has certain allelopathy.