2月 25 2014

利用种子袋技术分离附生兰种子萌发有效共生真菌的研究取得进展

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时间:2014-02-25   作者:字肖萌   高江云

        自然条件下,兰科植物种子由于缺乏胚乳,需要依靠特定共生真菌提供营养来促进其萌发和幼苗发育。兰科植物种子的共生萌发,是在获得对特定兰科植物种子萌发有效真菌的情况下,在人工基质中播种种子并接种共生真菌,利用真菌共生来促进种子萌发和获得幼苗。从理论上说,共生萌发不仅能简化幼苗生产过程,大大降低生产成本,更重要的是能显著提高幼苗回归到自然环境中后的存活率和幼苗生长速度。兰科植物种子共生萌发技术的应用,在珍稀濒危兰科植物的回归、药用兰科植物的仿生态栽培等方面都具有巨大的潜在价值,获得对种子萌发有效的共生真菌是开展兰科植物种子共生萌发的关键。

Fig. 1 Flower, fruit, and seed packets of D. aphyllum in XTBG Orchid Garden. a Inflorescence of D. aphyllum. b Outcross pollinated fruit of D. aphyllum. c One of the locationswe placed the seed packets in Orchid Garden. d Position and placement of seed packets

我组硕士研究生盛春玲和字肖萌,在导师高江云研究员地指导下,在西双版纳热带植物园(XTBG)选择沟谷雨林(RF)、兰园(OG),以及绿石林(GSF)三个区域中设置7个研究点,发展性地利用原地种子袋技术对西双版纳热带地区药用附生兰科植物兜唇石斛进行了有效促萌发真菌的分离、鉴定,并在实验室条件下进行离体共生萌发(in vitro symbiotic germination)对真菌和光照条件下不同萌发阶段效用进行了检测。本研究于研究点内自然生长或迁地回归的兜唇石斛种群的成熟植株根部附近放置共210个种子袋,10个月后进行回收得到161个种子袋,其中仅11个含有萌发了的原球茎或幼苗共55颗,从这些萌发的原球茎中一共分离到的9株真菌菌株,经鉴定为胶膜菌属(Tulasnella spp.)及木霉属(Trichoderma spp.)两种真菌。研究结果显示,与不接菌处理相比,Tulasnella菌株对种子萌发、原球茎形成及幼苗发育的有着显著促进作用(P均<0.0001),其效率分别高达13.6%、85.7%,以及45.2%;而Epulorhiza也能有效促进种子萌发(6.5%,P<0.05)和原球茎形成(20.3%,P<0.0001);然而Trichoderma却有着26.4%的萌发抑制率(P<0.0001)。对于接菌Tulasnella的处理中,光照对于种子吸胀、原球茎形成以及幼苗发育这三个阶段有着显著促进效用。研究结果表明原地种子袋技术在附生兰科植物种子与真菌共生关系研究中同样有着较高的可行性,光照对于附生兰科植物种子共生萌发有着重要作用,真菌与兰科植物种子之间除了存在种间共生特异性,还存在阶段共生特异性。

本研究为附生兰科植物的保护及回归研究提供了新的方法借鉴。正如审稿专家评价的“presents new data in an expanding and important area of orchid ecological and propagation science research. The application of seed/fungal baiting techniques to epiphytic orchid species is critical to the development of holistic and ecologically appropriate orchid seed propagation and conservation protocols”,“represents a special contribution to our fundamental understanding of epiphytic orchid seed germination requirements in situ involving mycorrhizal fungi”,“This study also sheds light into potential medicinal uses for epiphytic orchids infected with fungi under the framework of integrated conservation”。

相关研究结果以In situ seed baiting to isolate germination-enhancing fungi for an epiphytic orchid, Dendrobium aphyllum (Oechidaceae) 为题,在线发表于Mycorrhiza

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Fig. 4 Symbiotic seed germination of D. aphyllum (Success at each stage. is presented as a percentage. The thick black line in each plot indicate the 50th percentile values of each species, the lower and upper side of the box represent the 25th and 75th percentile, and the error bars the 10th and 90th percentile. The circles above or below the 10th and 90th percentile line represent data points that are more than three times the standard error for the observation (outliers). The line and stars above the boxplots connecting the light and dark treatments are for those comparisons that are significantly different. The significance P values are given as ***P<0.0001.) a Seed imbibition/ germination (Stage 1) when inoculated with different fungal strains under light or dark conditions. b Arrows show the imbibed seeds (Stage 1). c Protocorms formation (Stage 2) when inoculated with different fungal strain under light or dark condition. d Arrows show the formatted protocorms (Stage 2). e Protocorms development (Stage 3) when inoculated with different fungal strain under light or dark condition. f Arrows show the developed protocorms (Stage 3). g Seedlings formation (Stage 4) when inoculated with different fungal strain under light or dark condition. h Arrows show the formatted seedlings (Stage 4). i Seedlings development (Stage 5) when inoculated with different fungal strain under light or dark condition. j Arrows show the developed seedlings (Stage 5)

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