蘭菌、植物生長物質與石斛蘭的生長及有效成分moscatilin含量的相關性

Abstract

石斛為常用珍貴中藥，以新鮮或乾燥假球莖入藥，主要功能為生津明目，養胃清熱，潤肺養喉，然而野生藥用石斛生長相當緩慢，並於原生地遭大規模的開發採集，已有瀕臨絕種的危機。蘭共生菌為普遍存在於蘭科植物根內的內生真菌，以菌球消化或胞質逸出兩種感染模式共生於蘭科植物的根中，對蘭科植物的生長有促進效果。植物生長物質(Plant Growth Substances, PGS)為人工合成，具有能產生與植物激素相同生理效應的有機物，能應用於促進植物生長方面。Moscatilin為一最早由Dendrobium moscatum中分離出的雙苯環甲基衍生物，具有抑制癌細胞的活性。本試驗將藉由接種蘭共生菌及施加植物生長物質，期望能增加藥用石斛蘭的生長速率，及增加其藥用物質moscatilin之含量。接種並施用植物生長物質於銅皮石斛及鐵皮石斛小苗的結果顯示，施用甲殼素 (500 μL/ L)、氨基酸 (40 μg/ L)、品全王 (1000 μL/ L)及氨基酸加有機肥 (200 μL/ L)分別對兩種石斛株高、假球莖長、假球莖寬及葉片數有促進效果；其中氨基酸對兩種藥用石斛假球莖寬及葉片數都有促進效果。施用PGS配合接種蘭菌的試驗則以接種柱胞屬，Cylindrocarpon spp.(Cy)，配合施用氨基酸或太空精對兩種石斛的生長促進效果最佳。經分析了解國內數種觀賞及藥用石斛鮮品中，僅有金草石斛及黃花石斛兩種藥用石斛含有有效成分moscatilin；接種蘭菌對藥用石斛蘭內moscatilin含量的結果顯示，接種R01能顯著提高金草石斛中moscatilin的含量，在黃花石斛中則是接種R04能顯著促進其moscatilin量的增加。而在藥用石斛大苗接種蘭菌後，僅接種Cy對金草石斛地下部的生長有促進效果。經由掃描式電子顯微鏡觀察蘭菌感染石斛蘭的菌根構造，在不同品種石斛蘭根部細胞內，皆有發現絲核菌屬與柱孢菌屬的蘭菌形成菌球，顯示其感染模式屬菌球消化型，即菌根皮層細胞內含有菌絲團的構造產生。

The Dendrobium species have been commonly used in traditional Chinese medicine, by fresh or by dried pseudobulb, as a tonic to nourish the stomach, replenish body fluid and reduce fever. However, the wild Dendrobium spp. are endangered for their slow growing and had been extensively taken off from their native land. The orchid mychorrhiza fungi (OMF) belong to endomychorrizal fungi are generally found in the root cells of Orchid family. OMF normally inoculate and become symbiotic with orchid in the root cells by two ways: tolypophagy and ptyophagy. Growth improvement after inoculation of OMF had been found in several Orchid species. Plant growth substances (PGS) are synthetic compounds that have the same physiological effects as plant hormone and can be used to enhance plant growth. Moscatilin, a bibenzyl derivative originally purified from Dendrobium moscatum, is potentially efficacious against some kinds of cancer. An attempt to increase the growth rate of herbal dendrobium and the content of moscatilin was carried out by the inoculation of OMF and application of PGS in this study. Thus the inoculation of OMF and application of PGS in seedlings of Dendrobium candidum and D. moniliforme results were conducted, and showed that amino acid powder (40 μg/ L), Lysine#24 (1000 μL/ L), Chitosan (500 μL/ L), and amino acid/organic fertilizer mixed solution (200 μL/ L) increased plant height, pseudobulb length, width or leaf numbers of both Dendrobium spp. The inoculation of Cylindrocarpon spp.(Cy) together with application of amino acid powder were highly recommended in practical use for enhancing the growth of both Dendrobium seedlings. An analysis of several common herbal and ornamental dendrobiums in Taiwan, the result showed that only two herbal dendrobium, D. tosaense and D. clavatum, contained moscatilin in the pseudobulbs. The amount of moscatilin stored in the pseudobulb of D. clavatum inoculated with Rhizoctonia spp., R01, are higher than those of the non-mycorrhizal ones. Also the inoculation of R04 significantly increased the amount of moscatilin in the pseudobulb of D. tosaense. Inoculation of Cylindrocarpon spp. enhanced the root growth of mature D. clavatum thus higher root dry weight of D. clavatum was found after 200 days. It was observed that the mycorrhizal structure of different dendrobiums by scanning electron microscopy. Results showed that two genera of OMFs, Rhizoctonia spp. and Cylindrocarpon spp., forming peletons in the roots of inoculated dendrobiums. The infection mode of these two OMFs belong to tolypophagy, in which mycorrhizal cortex cells, peletons could be observed.