魔芋属植物组织培养与遗传转化研究进展

本文对近20年来魔芋生物技术研究取得的进展进行了系统的回顾分析。组织培养是当前魔芋生物技术研究的主要内容,魔芋离体植株再生以器官发生途径为主,包括不定芽和拟球茎两种途径,后者是当前研究的热点。利用组织培养进行有用突变体的筛选和种质资源的保存也取得了一些有价值的结果。以抗病和品质改良为目的的转基因技术取得了较快发展,如抗病基因和抗除草剂基因等已实现成功转化。此外,本文还分析了魔芋生物技术研究中存在的主要问题并提出了相应的对策。     

Stress‐tolerator leaf traits determine population dynamics in the endangered New Caledonian conifer Araucaria muelleri

Demographic and ecophysiological data for the endangered New Caledonian conifer, Araucaria muelleri (Araucariaceae), were analysed to: (i) evaluate population viability in relation to site conditions and human impacts; and (ii) advance our understanding of how stress‐tolerator plant functional traits affect the population dynamic behaviour and conservation requirements of long‐lived tree species. Growth, survivorship and recruitment in four A. muelleri populations were monitored across 9 years. Demographic rates were analysed using stage‐based transition matrices. Leaf δ¹³C, %N and photosystem II stress (Fv/Fm) were measured for seedlings, saplings and trees, and leaf mass per area (LMA) for trees, and correlations among ecophysiological and demographic variables explored. Seedling, sapling and tree stem growth were among the slowest, and annual survivorship among the highest, reported for any tree. Transition matrix analyses yielded stable estimated population growth rates, λ, not significantly different from 1.0 for all populations. Leaf δ¹³C was positively correlated with seedling and sapling height growth, while daytime photosystem II stress (Fv/Fm) was high in seedlings, but low in saplings and trees. Ecophysiological measures suggest that individuals transition from moisture‐limited growth at the seedling stage to nutrient‐limited growth as adults. High levels of environmental stress result in slow stand dynamics, characterized by low recruitment and growth rates counterbalanced by equally low mortality rates. These dynamics result in populations with limited capacity to increase in size quickly, but potentially highly vulnerable to decline should the rate of adult mortality increase. This combination of traits is likely typical of extreme stress‐tolerator woody species and suggests a conservation focus on the preservation of mature individuals.     

营养液酸碱度及光照强度对魔芋生长的影响

研究了pH3~10的不同营养液酸碱度在不同光照强度下对魔芋的生长状况及软腐病的发生率的影响。结果表明:魔芋最适宜的营养液环境为pH6~8,光照应控制在7000 Lux以下。在实际栽培中,应根据不同的光照强度适当调节营养液的酸碱度,以控制病害的发生。     

魔芋种质资源的AFLP分析

利用AFLP技术对13份魔芋种质资源进行了DNA多态性分析。从10对引物中筛选出2对引物扩增基因组DNA,共获得112条带,其中64条为多态性标记,每个引物平均提供56个标记信息。UPMGA法聚类分析结果表明:魔芋资源的遗传多态性比较丰富,西盟魔芋和珠芽魔芋的关系比较近,白魔芋和花魔芋的关系比较近。     

花魔芋软腐病原真菌分离鉴定

魔芋软腐病是魔芋生产过程中的重要病害,也是限制魔芋产业发展的主要因素。目前,已有报道魔芋软腐病主要由细菌引起,鲜有真菌引起魔芋球茎软腐发病的报道。为明确云南曲靖市花魔芋(Amorphophallus konjac)软腐病的病原种类和侵染特征,该研究通过组织分离法,对采集自云南曲靖市的花魔芋病样进行了真菌的分离,通过形态学结合基于ITS与LSU序列分析的分子鉴定方法对分离真菌进行鉴定,并根据柯赫氏法则进行致病性测定,并对鉴定出的病原真菌同魔芋软腐病原细菌进行了双回接试验分析。结果表明:(1)从形态学和分子水平鉴定了轮纹镰刀菌(Fusarium concentricum)、尖孢镰刀菌(F. oxysporum)和F. ambrosium 3种镰刀菌,1种毛霉属真菌(Mucor sp.),1种根霉属真菌(Rhizopus sp.),1种青霉属真菌(Penicillium sp.)和1种粉红螺旋聚孢霉属真菌(Clonostachys sp.)。(2)统计分析发现,轮纹镰刀菌的相对丰度最高,为45.45%。(3)柯赫氏法则检测发现轮纹镰刀菌具有致病性。(4)轮纹镰刀菌和病原细菌胡萝卜果胶杆菌(Pectobacterium aroidearum)双接种魔芋球茎发现软腐病发病更快,病变组织重量显著高于单接种轮纹镰刀菌或果胶杆菌处理。综上表明,魔芋软腐病可能是由真菌和细菌复合侵染引发。该研究结果为魔芋软腐病的防治提供了理论依据。     

Taro koji of Amorphophallus konjac enabling hydrolysis of konjac polysaccharides to various biotechnological interest

ABSTRACT

Due to the indigestibility, utilization of konjac taro, Amorphophallus konjac has been limited only to the Japanese traditional konjac food. Koji preparation with konjac taro was examined to utilize konjac taro as a source of utilizable carbohydrates. Aspergillus luchuensis AKU 3302 was selected as a favorable strain for koji preparation, while Aspergillus oryzae used extensively in sake brewing industry was not so effective. Asp. luchuensis grew well over steamed konjac taro by extending hyphae with least conidia formation. Koji preparation was completed after 3-day incubation at 30°C. D-Mannose and D-glucose were the major monosaccharides found in a hydrolyzate giving the total sugar yield of 50 g from 100 g of dried konjac taro. An apparent extent of konjac taro hydrolysis at 55°C for 24 h seemed to be completed. Since konjac taro is hydrolyzed into monosaccharides, utilization of konjac taro carbohydrates may become possible to various products of biotechnological interest.     

A soft computing tool for species classification and prediction of glucomannan content in Amorphophallus genus

The proposed work aims at designing a classification system for automatic identification of A. muelleri species, grown as a potential cash crop in many Asian countries, from the DNA fingerprints of Amorphophallus genus. Four sets of 48 DNA fingerprints belonging to 37 species of the Amorphophallus genus, developed with the help of four different primers are considered for the experiment, with an objective to identify only the fingerprints of the species of interest. A second experimental setup deals with the automatic classification of species containing high amounts of glucomannan from the same set of DNA fingerprints of the Amorphophallus genus. For each set of 48 DNA fingerprints generated with a specific primer, the DNA fingerprints are preprocessed to extract a 42 dimensional feature vector which is used to generate a k‐Nearest Neighbor based classifier based on the Leave One Out Cross Validation protocol. Final classification based on outputs from individual classifiers constructed with respect to the four different primers is performed according to a n‐star consensus strategy. The n‐star consensus predicts species A. muelleri with cent per cent accuracy while it predicts species containing glucomannan with a more modest accuracy of 81.25%.     

金沙江干热河谷特有植物白魔芋的传粉生物学研究

以金沙江干热河谷特有植物白魔芋（Amorphophallus albus P.Y.Liu et J.F.Chen）为对象，分别在两个就地栽培实验地（四川金阳、云南永善）和一个异地栽培实验地（富源）进行传粉生物学研究（包括交配系统及气味和传粉昆虫对其繁殖策略的影响）。结果显示，白魔芋是雌雄异熟且雌蕊先熟，雌花期时，附属器散发浓烈的恶臭气味。经气相色谱-质谱联用仪（GC-MS）分析，花气味成分主要为二甲基二硫和二甲基三硫。野外观察到的传粉昆虫属于隐翅虫科（Staphylinidae），包括前角隐翅虫亚科（Aleocharinae）的Atheta sp.和颈隐翅虫亚科（Oxytelinae）的Anotylus sp.。经气相色谱-触角电位联用技术（GC-EAD）分析表明，隐翅虫触角对白魔芋花气味中的二甲基二硫和二甲基三硫有明显的反应。授粉结果显示，金阳、永善和富源3个实验地人工自花授粉和套袋的结实率都为0，无传粉昆虫的富源实验地自然结实率也为0。综合研究结果表明白魔芋属于自交不亲和的交配系统，通过花序结构和气味吸引隐翅虫为其传粉，并提供食物和交配场所作为回报。该研究为白魔芋的繁殖育种提供了基础资料，为植物与昆虫之间的协同进化提供了进一步的理论支持，同时为白魔芋的有效保护和利用提供了理论依据和技术指导。     

A torch in the rain forest: thermogenesis of the Titan arum (Amorphophallus titanum)

An outstanding flagship species in the plant kingdom is the Titan arum ( Amorphophallus titanum ), which produces a fountain-like bloom up to 3 m high. The unique appearance of three simultaneous inflorescences in May 2006 was a chance to analyse the flowering behaviour and thermogenesis of this giant. For the first time, the heating of the central column (spadix) could be documented using a high-performance thermographic camera. Time series analyses of the infrared image sequences revealed that the 3-m high spadix surface heats up in pulses emanating from the base of the inflorescence. The surface temperature reaches over 36 °C, compared to the ambient temperature of 27 °C. Waves of the carrion-like odour are synchronised with these heat pulses. The combination of heat pulses, the fountain-like shape plus the enormous size lead to a unique type of 'convection flower'. On the basis of our observations, we assume that Amorphophallus titanum is able to overcome thermodynamic decoupling by a self-produced convective process.