植物内生菌的开发与研究进展

植物的内生菌是巨大的资源宝库,具有重大的研究和开发价值。对近年来植物内生菌的开发与研究进展进行了综述,包括内生菌的起源、分布特点、分离方法,内生菌在医药、生物防治、对污染物的降解等开发与应用方面的研究进展。     

玉米内生细菌资源研究进展

植物内生菌存在于植物的各个器官,种类繁多,对植物的生长发育具有重要作用。玉米是最重要粮食作物之一,通过研究玉米与其内生细菌的关系,对增产玉米以及生物防治有积极意义。本文归纳了玉米内生细菌资源的分离与收集,包括内生细菌的多样性及新种的鉴定;介绍了玉米内生细菌与宿主的相关性;总结了玉米内生细菌的生物学作用,包括抑菌性、耐受性、固氮作用和促生作用,以及内生细菌对玉米作用机制;并对玉米内生细菌研究趋势进行了前景展望,旨在为玉米内生细菌的研究提供参考。     

植物内生真菌——一类应用前景广阔的资源微生物

从内生真菌的基本生物学特征出发,着重对近年来关于植物内生真菌的生物学作用方面的研究情况进行了综述,主要包括内生真菌对植物生长发育及其抗逆性的促进作用、内生真菌与生物防治、内生真菌与抗癌药物的开发等。最后还对内生真菌的实际应用中存在的问题和可能采取的提供进行了总结。     

植物内生真菌---类应用前景广阔的资源微生物

从内生真菌的基本生物学特征出发,着重对近年来关于植物内生真菌的生物学作用方面的研究情况进行了综述,主要包括内生真菌对植物生长发育及其抗逆性的促进作用、内生真菌与生物防治、内生真菌与抗癌药物的开发等.最后还对内生真菌在实际应用中存在的问题和可能采取的措施进行了总结.     

植物内生真菌——一类应用前景广阔的资源微生物*

从内生真菌的基本生物学特征出发 ,着重对近年来关于植物内生真菌的生物学作用方面的研究情况进行了综述 ,主要包括内生真菌对植物生长发育及其抗逆性的促进作用、内生真菌与生物防治、内生真菌与抗癌药物的开发等。最后还对内生真菌在实际应用中存在的问题和可能采取的措施进行了总结。     

植物-内生真菌共生体对昆虫种群的影响

植物内生真菌与植食性昆虫共用寄主植物作为食物、能量来源及栖息场所,三者之间的互作关系复杂多变,在生物种群控制、生物进化和植物生产中发挥重要作用.从植物-内生真菌共生体、内生真菌对植食性昆虫与多级营养层的影响,及内生真菌抗虫代谢产物等方面概括了内生真菌-植物-昆虫相互关系的研究进展,建议将植物内生真菌纳入植物生态学、昆虫生态学和作物病虫害控制的范畴内.     

植物内生菌的研究进展

植物内生菌是存在于植物内部与植物密不可分的一类微生物,包括内生真菌和内生细菌两大类。随着研究的不断深入,发现内生菌不仅产生多种有益的生物学作用,如防病、促生、固氮等,还能对寄主植物的生长发育产生不利影响。近年来,植物内生菌已成为我国微生物学领域研究的热点问题之一。本文综述了植物内生真菌和内生细菌的研究概况,以期更好地研究和了解植物内生菌。     

植物内生菌群落组成及其功能研究进展

植物内生菌是栖居在植物组织内部、以宿主植物代谢物为营养物质的一类微生物。植物内生菌种类丰富,并通过不同的方式定殖在植物体内,与宿主植物互利共生。植物内生菌促进植物的生长发育,通过增强营养物质吸收、与病原菌竞争生态位、在代谢过程中产生抗菌物质以及诱导宿主植物产生抗性等机制,提高宿主植物的抗逆性,并且其群落的组成因生态环境、寄主植物不同部位、生长周期的不同发育阶段而显著不同。人们利用传统组织分离法、高通量测序法以及人工重组生物群落等研究方法对植物与内生菌相互作用进行了深入的研究。本文对植物内生菌群落的组成、内生菌对宿主植物影响的功能研究以及人工内生菌群的构建进行重点阐述,以期为植物内生菌的开发和利用奠定坚实基础。     

植物内生固氮菌研究进展

综述了植物内生固氮菌生物多样性、生物学特性 ,生理特性 ,与寄主植物的相互作用及应用前景等方面的研究进展。     

内生真菌对植物抗旱性的影响

内生真菌广泛地存在于植物体内,它们在植物体内的生活不会对植物引起任何感病症状,而且内生真菌侵染对植物生长、生物和非生物胁迫抗性很好的促进作用,理解内生真菌在提高植物干旱胁迫耐受性方面的作用和机理对其在缓解植物干旱胁迫中的应用有重要意义。这篇综述介绍了植物内生真菌的多样性、对植物抗旱性的影响及其作用机理等方面的研究进展。内生真菌对植物抗旱性提高的机理包括:干旱耐受、干旱回避和干旱恢复。文中还对以后的研究进行了展望。     

Fungal endophytes and phytochemistry of oak foliage: determinants of oviposition preference of leafminers?

Sedentary insect herbivores, such as gallformers and leafminers, are usually non-randomly distributed among and within host plants. Dispersion of these insects is largely a function of female oviposition choice. In field experiments and observations spanning two growing seasons, we tested the hypothesis that selective oviposition on individual leaves within trees by the dominant herbivore of Emory oak, the monophagous leaf-miner Cameraria sp. nov., is determined by the probability of colonization by endophytic fungi. These fungi are alleged to act as plant mutualists by deterring, killing, or inhibiting the growth of insect herbivores. We found that leaves selected by females for oviposition and paired, unmined leaves were equally likely to be colonized by fungal endophytes. Furthermore, condensed and hydrolyzable tannin levels, purported inhibitors of fungal infection, and protein content did not vary between leaves selected by females and unmined leaves, or between leaves with and without endophyte infections. We conclude that female Cameraria do not choose leaves within trees for oviposition on the basis of propensity for endophytic fungal infection or on phytochemical parameters that might indicate probability of future infections. At this spatial scale at least, fungal endophytes do not explain the highly aggregated distribution of Cameraria among leaves and associated costs in terms of increased larval mortality. Fungal endophytes may, nevertheless, affect leafminer dispersion and abundance at larger spatial scales, such as host plant populations or species. We did find, however, that the amount of mining activity on leaves is positively associated with increased colonization by fungal endophytes. We suggest that mining activity increases endophyte fungal infections by facilitating spore germination and hyphal penetration into the leaf or by altering leaf phytochemistry. The facilitation of endophyte colonization by leafmining activity coupled with the lack of predictability of endophyte infections based on leaf phytochemistry and almost 100% infectivity of all oak leaves during sporadic wet years may prevent female leafminers from discriminating leaves for oviposition on the basis of current or future levels of endophytes in leaves.     

Birch family and environmental conditions affect endophytic fungi in leaves

We investigated whether variation in foliar endophyte frequency among mountain birch trees from different maternal families was due in part to genetic differences among trees. The effect of different environmental conditions on the susceptibility of these mountain birch families to foliar endophytes was tested. The 3-year study was conducted in two tree gardens (altitudinal difference 180 m) with ten families of mountain birch. The frequency of the commonest endophytic fungus in mountain birch leaves, Fusicladium sp., was significantly affected by mountain birch family, with the ranking of families relative to Fusicladium sp. frequency being consistent from environment to environment. Variation in the frequency of Melanconium sp. was difficult to interpret because of significant family × garden × year interaction. Fusicladium sp. and Melanconium sp. endophytes were most frequent in different tree individuals, families and gardens. We conclude that mountain birch trees show heritable variation in their foliar endophyte frequency, and thus one of the conditions necessary for foliar endophytes of mountain birch trees to be able to affect the evolution of their host plant is fulfilled. However, the effect of mountain birch family on the frequency of endophytic fungi varies depending on the endophytic genera in question and partially also on environmental conditions. Received: 28 March 1998 / Accepted: 14 October 1998     

Diversity,community composition,and bioactivity of cultivable fungal endophytes in saline and dry soils in deserts

Fungal endophyte communities are poorly investigated in extreme habitats such as deserts. We used cultivation and Sanger sequencing to investigate the effects of environmental variables on the endophytic fungal communities of eight Iranian desert plants. Host species was the main factor shaping the endophyte composition, while soil type additionally affected endophytes of above- and below-ground organs. Redundancy analysis showed that soil pH and electric conductivity determine fungal endophyte communities in plants in dry and saline soils. In a follow-up experiment, we showed that these endophytes could be used in crop production under salinity/drought stress and as biocontrol agents. Although compared to other ecosystems, the endophytic fungi associated with the studied Iranian desert plants are of low diversity, our results suggest that they probably play an essential role in the survival of their hosts. Further investigation is necessary to evaluate the potential benefits and applicability of such endophytes in agricultural practices in drylands.     

禾本科植物内生真菌资源及其物种多样性

植物内生真菌是当代微生物资源研究的一个热门话题,对禾本科植物内生真菌资源研究进行了总结。与冷季型禾本科植物共生的麦角菌科epichlo内生真菌是目前的研究重点,包括偶尔在宿主植物体表形成子座的Epichlo属真菌和几乎完全不形成症状的Neotyphodium属真菌。具体介绍该真菌类群的物种多样性及其地理分布多样性,概括了它们在全球各大区域的分布特征。对近年来中国迅速发展的epichlo内生真菌的研究作了总结,最后展望了国际国内epichlo内生真菌资源探索的发展方向。特别指出:冷季型禾本科植物内生真菌在南美洲和亚洲,暖季型禾本科植物内生真菌在热带亚热带地区的研究还相对薄弱,值得今后继续加强探索和挖掘。     

Two fungal symbioses collide: endophytic fungi are not welcome in leaf-cutting ant gardens

Interactions among the component members of different symbioses are not well studied. For example, leaf-cutting ants maintain an obligate symbiosis with their fungal garden, while the leaf material they provide to their garden is usually filled with endophytic fungi. The ants and their cultivar may interact with hundreds of endophytic fungal species, yet little is known about these interactions. Experimental manipulations showed that (i) ants spend more time cutting leaves from a tropical vine, Merremia umbellata, with high versus low endophyte densities, (ii) ants reduce the amount of endophytic fungi in leaves before planting them in their gardens, (iii) the ants'' fungal cultivar inhibits the growth of most endophytes tested. Moreover, the inhibition by the ants'' cultivar was relatively greater for more rapidly growing endophyte strains that could potentially out-compete or overtake the garden. Our results suggest that endophytes are not welcome in the garden, and that the ants and their cultivar combine ant hygiene behaviour with fungal inhibition to reduce endophyte activity in the nest.     

广藿香内生真菌多样性及其对青枯菌的拮抗活性

【目的】对广藿香各部位内生真菌的类群结构及多样性进行系统分析,筛选出对青枯菌具拮抗活性的菌株。【方法】采用组织块分离法从广藿香健康植株的根、茎、叶中分离内生真菌,结合形态学和基于ITS-r DNA序列分析鉴定方法分析广藿香内生真菌的类群结构及多样性,并利用双层平板拮抗法筛选对青枯菌具有抑制活性的菌株。【结果】从广藿香中共分离获得313株内生真菌,隶属于30个属,其中链格孢属(占28.75%)、拟茎点霉属(占23.00%)和炭疽菌属(11.82%)为优势类群,此外还分离到炭皮菌属、弯孢聚壳属、Gibellulopsis、新萨托菌属、葡萄座腔菌属、篮状菌属等较为少见的类群。茎、叶内生真菌的定殖率和分离率明显高于根,而根部多样性指数为2.64,要高于茎(2.00)和叶(1.97);广藿香茎与叶、根与茎、根与叶之间的内生真菌相似性指数分别为0.35、0.20、0.19,均小于0.5,显示各部位之间的内生真菌组成不相似程度高。从313株广藿香内生真菌中通过拮抗实验筛选到16株对青枯菌有拮抗活性的菌株,其中GHXR07、GHXR27和GHXR29的拮抗活性尤为显著,分别被鉴定为Talaromyces sp.、Myrothecium roridum Tode和Talaromyces wortmannii(Kl?cker)Benjamin。【结论】广藿香内生真菌具有丰富的物种多样性且其类群分布具有一定的组织特异性,其中部分菌株对青枯菌具有明显的拮抗活性。     

Effects of endophyte infection on the competitive ability of Achnatherum sibiricum depend on endophyte species and nitrogen availability

Aims The leaves of almost all terrestrial plant species are colonized by endophytic fungi. Compared to agronomic grasses, which usually harbor few endophytes, native grasses generally possess greater endophyte species diversity. Existing studies examining endophyte effects on natural grasses under competition normally considered the infection status (infected or uninfected), and rarely considered endophyte species.     

The effect of endophytic Peyronellaea from heavy metal-contaminated and uncontaminated sites on maize growth,heavy metal absorption and accumulation

Heavy metal (HM) tolerance, effects on maize growth, heavy metal absorption and accumulation by endophytic Peyronellaea from HM-contaminated and uncontaminated sites were studied to evaluate the hypothesis that endophytes from HM-contaminated sites would enhance HM-tolerance in hosts. Although we found that certain endophytes improved tolerance of plants to heavy metals, isolates from the HM-contaminated site were not more tolerant to heavy metals than those from the uncontaminated site. Pot experiments indicated that growth and heavy metal absorption and accumulation by host plants in HM-polluted environments could be affected by inoculation with HM-tolerant endophytic fungi, and isolates showed a high intraspecific variability. However, there was no significant difference in growth between the maize inoculated with the endophytes from the HM-contaminated site and uncontaminated site under lead stress. Similarly, the HM content in the shoots and roots of maize inoculated with the isolates from the HM-contaminated site was not always higher than that in maize inoculated with endophytes from the uncontaminated site. Therefore, based on our experiments it is suggested that HM-tolerance due to endophytes and their effects on host plant growth and heavy metal absorption and accumulation were not correlated with origin of the endophytes.     

Interactions between host plants,endophytic fungi,and a phytophagous insect in an oak (Quercus grisea x Q. gambelii) hybrid zone

We examined interactions between host plants, endophytic fungi, and leaf-mining moths (Phyllonorycter sp.) in an oak (Quercus grisea x Q. gambelii) hybrid zone. The community of endophytic fungi and two common endophyte species examined responded to host plant hybridization. Total fungal frequency (TFF) and frequency of Gnomonia cerastis were lowest on hosts resembling Q. grisea, and increased linearly towards those resembling Q. gambelii. In contrast, Coccochorella quercicola was most frequently isolated from Q. grisea-like hosts and decreased in frequency across hybrids towards Q. gambelii. Frequency of G. cerastis and TFF covaried with Phyllonorycter density across the hybrid zone, but direct effects of endophytes on Phyllonorycter density were not detected. Associations between endophytes and unexplained mortality of Phyllonorycter varied according to endophyte species and state of Phyllonorycter development. In the sap-feeding stage, unexplained mortality was negatively associated with TFF and frequencies of Hormonema sp. and Preussia funiculata; whereas, in the tissue-feeding stage, unexplained Phyllonorycter mortality was positively associated with G. cerastis frequency. Three-way interactions between plant hybridization, endophytic fungi, and the insect herbivore were not significant.