Cadmium‐induced and trans‐generational changes in the cultivable and total seed endophytic community of Arabidopsis thaliana

Trans‐generational adaptation is important to respond rapidly to environmental challenges and increase overall plant fitness. Besides well‐known mechanisms such as epigenetic modifications, vertically transmitted endophytic bacteria might contribute to this process. The cultivable and total endophytic communities of several generations of Arabidopsis thaliana seeds harvested from plants exposed to cadmium (Cd) or not exposed were investigated. The diversity and richness of the seed endophytic community decreased with an increasing number of generations. Aeromicrobium and Pseudonocardia were identified as indicator species in seeds from Cd‐exposed plants, while Rhizobium was abundantly present in both seed types. Remarkably, Rhizobium was the only genus that was consistently detected in seeds of all generations, which suggests that the phenotypic characteristics were more important as selection criteria for which bacteria are transferred to the next plant generation than the actual genera. Production of IAA was an important trait for endophytes from both seed types, while ACC deaminase activity and Cd tolerance were mainly associated with seed endophytes from Cd‐exposed plants. Understanding how different factors influence the seed endophytic community can help us to improve seed quality and plant growth through different biotechnological applications.     

The Effect of Long-Term Cd and Ni Exposure on Seed Endophytes of Agrostis capillaris and Their Potential Application in Phytoremediation of Metal-Contaminated Soils

We examined whether long-term Cd exposure leads to beneficial changes in the cultivable endophytic bacteria present in the seeds of Agrostis capillaris. Therefore the cultivable seed endophytes of Agrostis capillaris growing on a long-term Cd/Ni-contaminated plot (Cd/Ni seeds) were compared with those originating from a non-contaminated plot (control seeds). We observed plant- and contaminant-dependent effects on the population composition between control and Cd/Ni seeds. Also differences in phenotypic characteristics were found: endophytes from Cd/Ni seeds exhibited more ACC deaminase activity and production of siderophores and IAA, while endophytes from control seeds, very surprisingly, showed more metal tolerance.

Finally, the 3 most promising seed endophytes were selected based on their metal tolerance and plant growth promoting potential, and inoculated in Agrostis capillaris seedlings. In case of non-exposed plants, inoculation resulted in a significantly improved plant growth; after inoculation of Cd-exposed plants an increased Cd uptake was achieved without affecting plant growth. This indicates that inoculation of Agrostis with its seed endophytes might be beneficial for its establishment during phytoextraction and phytostabilisation of Cd-contaminated soils.     

ENDOPHYTIC BACTERIA FROM SEEDS OF NICOTIANA TABACUM CAN REDUCE CADMIUM PHYTOTOXICITY

Although endophytic bacteria seem to have a close association with their host plant, little is known about the influence of seed endophytic bacteria on initial plant development and on their interactions with plants under conditions of metal toxicity. In order to further elucidate this close relationship, we isolated endophytic bacteria from surface sterilized Nicotiana tabacum seeds that were collected from plants cultivated on a cadmium-(Cd) and zinc-enriched soil. Many of the isolated strains showed Cd tolerance. Sterilely grown tobacco plants were inoculated with either the endogenous microbial consortium, composed of cultivable and noncultivable strains; single strains; or defined consortia of the most representative cultivable strains. Subsequently, the effects of inoculation of endophytic bacteria on plant development and on metal and nutrient uptake were explored under conditions with and without exposure to Cd. In general, seed endophytes were found to have a positive effect on plant growth, as was illustrated by an increase in biomass production under conditions without Cd. In several cases, inoculation with endophytes resulted in improved biomass production under conditions of Cd stress, as well as in a higher plant Cd concentration and total plant Cd content compared to noninoculated plants. These results demonstrate the beneficial effects of seed endophytes on metal toxicity and accumulation, and suggest practical applications using inoculated seeds as a vector for plant beneficial bacteria.     

Rock-degrading endophytic bacteria in cacti

A plant–bacterium association of the cardon cactus (Pachycereus pringlei) and endophytic bacteria promotes establishment of seedlings and growth on igneous rocks without soil. These bacteria weather several rock types and minerals, unbind significant amounts of useful minerals for plants from the rocks, fix in vitro N₂, produce volatile and non-volatile organic acids, and reduce rock particle size to form mineral soil. This study revealed the presence of large populations of culturable endophytic bacteria inside the seeds extracted from wild plants, from seeds extracted from the guano of bats feeding on cactus fruit, in seedlings growing from these seeds, in the pulp of fruit, and in small, mature wild plants, and are comparable in size to populations of endophytic populations in some agricultural crops. The dominant culturable endophytes were isolates of the genera Bacillus spp., Klebsiella spp., Staphylococcus spp., and Pseudomonas spp. Based on partial sequencing of the 16s rRNA gene, the isolated strains had low similarity to known strains in these genera. However, these strains have higher molecular similarity among endophytes obtained from seeds, endophytes from roots, and some bacterial strains from the rhizoplane. Seedlings developed from seeds with endophytes contain the similar species of endophytes in their shoots, possibly derived from the seeds. This study shows the involvement of endophytic bacteria in rock weathering by cacti in a hot, subtropical desert and their possible contribution to primary colonization of barren rock. This study proposes that cacti capable of acquiring diverse populations of endophytes may give them an evolutionary advantage to gain a foothold on highly uncompromising terrain.     

Bacteria associated with yellow lupine grown on a metal‐contaminated soil: in vitro screening and in vivo evaluation for their potential to enhance Cd phytoextraction

In order to stimulate selection for plant‐associated bacteria with the potential to improve Cd phytoextraction, yellow lupine plants were grown on a metal‐contaminated field soil. It was hypothesised that growing these plants on this contaminated soil, which is a source of bacteria possessing different traits to cope with Cd, could enhance colonisation of lupine with potential plant‐associated bacteria that could then be inoculated in Cd‐exposed plants to reduce Cd phytotoxicity and enhance Cd uptake. All cultivable bacteria from rhizosphere, root and stem were isolated and genotypically and phenotypically characterised. Many of the rhizobacteria and root endophytes produce siderophores, organic acids, indole‐3‐acetic acid (IAA) and aminocyclopropane‐1‐carboxylate (ACC) deaminase, as well as being resistant to Cd and Zn. Most of the stem endophytes could produce organic acids (73.8%) and IAA (74.3%), however, only a minor fraction (up to 0.7%) were Cd or Zn resistant or could produce siderophores or ACC deaminase. A siderophore‐ and ACC deaminase‐producing, highly Cd‐resistant Rhizobium sp. from the rhizosphere, a siderophore‐, organic acid‐, IAA‐ and ACC deaminase‐producing highly Cd‐resistant Pseudomonas sp. colonising the roots, a highly Cd‐ and Zn‐resistant organic acid and IAA‐producing Clavibacter sp. present in the stem, and a consortium composed of these three strains were inoculated into non‐exposed and Cd‐exposed yellow lupine plants. Although all selected strains possessed promising in vitro characteristics to improve Cd phytoextraction, inoculation of none of the strains (i) reduced Cd phytotoxicity nor (ii) strongly affected plant Cd uptake. This work highlights that in vitro characterisation of bacteria is not sufficient to predict the in vivo behaviour of bacteria in interaction with their host plants.     

Diversity of fungal endophytes in some medicinal plants of Himachal Pradesh,India

Fungal endophytes were isolated from surface sterilised leaf segments of five medicinal plants collected from Mandi district, Himachal Pradesh, India. A total of 373 fungal strains belonging to 15 fungal genera and 18 species, Aspergillus niger, A. flavus, A. clavatus, A. variecolor, Penicillium chrsogenum, Alternaria alternata, Curvularia lunata, Haplosporium sp., Phoma sp., Nigrospora sp., Colletotrichum sp., Cladosporium sp., Stemphylium sp., Fusarium sp., Geotrichum sp., Phomopsis sp., Trichoderma sp., Rhizopus sp. and some sterile mycelium were isolated from all the plants. The relative frequency, isolation rate and colonisation rates of endophytes were used to study the endophytic diversity. The results showed that the highest colonisation rate (93.05%) was observed in Adhathoda vasica, while it was 91.66% in Ocimum sanctum, 85% in Viola odorata, 82.81% Cannabis sativa and lowest (61.11%) in Withania somnifera. Moreover, reading the richness and diversity of the endophytic fungi, the highest was obtained for O. sanctum, W. somnifera and C. sativa having eight species each, while lowest (6 and 4) was obtained from A. vasica and V. odorata, respectively. As the role of endophytic organisms in defensive mechanisms of plants is now well established, the present study is an important step to find new and interesting endophytes among the medicinal plants.     

Effect of host genotype on indigenous bacterial endophytes of cotton (Gossypium hirsutum L.)

The purpose of this study was to determine if populations of indigenous bacterial endophytes in seed, stem and root tissue of cotton seedlings are influenced by host genotype. Growth chamber and field experiments were conducted to test the hypothesis that host genotype has an effect on endophytic bacterial populations in seed tissues and the developing cotton seedling. Initially, population densities of bacteria within seed of nine cotton cultivars were very low (i.e., 10 2.0 colony forming units seed^–1). However, after 4 days growth on water agar, population densities within developing radicles increased significantly (log₁₀ 2–5 colony forming units) and significant cultivar differences were found. Significant cultivar differences occurred for populations of endophytic bacteria and the composition of bacterial functional groups differed among cultivars in field-grown seedlings at 5, 8, and 15 days after planting. Differences in the ranking of cultivars occurred for endophytic populations recovered from seed and aseptically and field-grown radicle and seedling tissues. These results suggest that whether originating from seed or from soil, cotton plants are capable of immediately establishing a carrying capacity for communities of endophytic bacteria following seed germination. During germination and development of the seedling, there are genetic and possible morphological/physiological effects that contribute to significant differences in colonization of bacterial endophytes among cotton cultivars.     

药用植物青蒿不同种类的内生菌抑菌活性分析

为了研究青蒿不同种类的内生菌抑制细菌和抑制真菌的活性,该研究采用组织块法和研磨法从青蒿的根、茎、叶中分离内生细菌、放线菌和真菌,以大肠埃希菌(Escherichia coli)(CICC 23657)、枯草芽孢杆菌(Bacillus subtilis)(CICC 10275)、金黄色葡萄球菌(Staphylococcu...     

Endophytes of Grapevine Flowers,Berries, and Seeds: Identification of Cultivable Bacteria,Comparison with Other Plant Parts,and Visualization of Niches of Colonization

Endophytic bacteria can colonize various plants and organs. However, endophytes colonizing plant reproductive organs have been rarely analyzed. In this study, endophytes colonizing flowers as well as berries and seeds of grapevine plants grown under natural conditions were investigated by cultivation as well as by fluorescence in situ hybridization. For comparison, bacteria were additionally isolated from other plant parts and the rhizosphere and characterized. Flowers, fruits, and seeds hosted various endophytic bacteria. Some taxa were specifically isolated from plant reproductive organs, whereas others were also detected in the rhizosphere, endorhiza or grape inflo/infructescence stalk at the flowering or berry harvest stage. Microscopic analysis by fluorescence in situ hybridization of resin-embedded samples confirmed the presence of the isolated taxa in plant reproductive organs and enabled us to localize them within the plant. Gammaproteobacteria (including Pseudomonas spp.) and Firmicutes (including Bacillus spp.) were visualized inside the epidermis and xylem of ovary and/or inside flower ovules. Firmicutes, mainly Bacillus spp. were additionally visualized inside berries, in the intercellular spaces of pulp cells and/or xylem of pulp, but also along some cell walls inside parts of seeds. Analysis of cultivable bacteria as well as microscopic results indicated that certain endophytic bacteria can colonize flowers, berries, or seeds. Our results also indicated that some specific taxa may not only derive from the root environment but also from other sources such as the anthosphere.     

Characterization of bacterial communities associated with Brassica napus L. growing on a Zn-contaminated soil and their effects on root growth

The interaction between plant growth-promoting bacteria (PGPB) and plants can enhance biomass production and metal tolerance of the host plants. This work aimed at isolating and characterizing the cultivable bacterial community associated with Brassica napus growing on a Zn-contaminated site, for selecting cultivable PGPB that might enhance biomass production and metal tolerance of energy crops. The effects of some of these bacterial strains on root growth of B. napus exposed to increasing Zn and Cd concentrations were assessed. A total of 426 morphologically different bacterial strains were isolated from the soil, the rhizosphere, and the roots and stems of B. napus. The diversity of the isolated bacterial populations was similar in rhizosphere and roots, but lower in soil and stem compartments. Burkoholderia, Alcaligenes, Agrococcus, Polaromonas, Stenotrophomonas, Serratia, Microbacterium, and Caulobacter were found as root endophytes exclusively. The inoculation of seeds with Pseudomonas sp. strains 228 and 256, and Serratia sp. strain 246 facilitated the root development of B. napus at 1,000 µM Zn. Arthrobacter sp. strain 222, Serratia sp. strain 246, and Pseudomonas sp. 228 and 262 increased the root length at 300 µM Cd.     

Endophytic fungi alter foraging and dispersal by desert seed-harvesting ants

Endophytic fungi are thought to interact mutualistically with host plants by producing alkaloid metabolites that deter herbivory. Since such fungi are transmitted via seed in some grasses, the presence of endophytes may also protect plants from seed predators. We conducted seed choice experiments for two dominant seed harvesting ants, Pogonomyrmex rugosus in the Sonoran desert and Pogonomyrmex occidentalis at a higher elevation, riparian zone in Arizona, USA. Non-infected fescue (Festuca arundinacea) seeds and seeds infected with the endophytic fungus, Acremonium coenophialum, were presented to ant colonies in three different populations. Infected seeds were harvested less frequently than non-infected seed for the two populations of Pogonomyrmex rugosus but not for the population of Pogonomyrmex occidentalis. We also a conducted seed dispersal experiment for one population of Pogonomyrmex rugosus. Of the seeds that were harvested, most of the colonies discarded more infected seeds into refuse piles than expected by chance. Seeds discarded into refuse piles have greater germination success than surrounding areas. The most important interaction of endophytes and grasses may be deterrence of seed predation and enhancing the probability of germinating in favorable sites, since these processes directly increase plant fitness.     

豚草种带内生真菌及其对种子发芽和幼苗生长的影响

内生真菌是一类共生于植物体内,能够不同程度影响宿主植物生态适应性和竞争能力的微生物。分析内生真菌在豚草种子中的分布、种群结构,以及内生真菌发酵液对种子发芽和幼苗生长的作用。结果显示:发生于6个地区的豚草种子均能分离获得内生真菌,分离率在19%—92.63%之间,不同地区之间差异极显著(P0.01)。内生真菌主要存在于种子的总苞部位,分离率达到65.52%。发生于福建省长乐市松下镇的豚草种带内生真菌种群包含5个属,以链格孢属(Alternaria)真菌为优势菌群,占82.26%;其次为镰孢属(Fusarium)真菌,占9.68%;其它3个属的真菌发生较少,均低于5%。内生真菌主要以水平传播方式在豚草不同世代之间传播。供试的7个内生真菌菌株的发酵液均不同程度地抑制豚草种子发芽,降低幼苗地上部高度、根长度、根数量和总生物量,但不同菌株发酵液之间抑制程度差异明显,显示不同菌株对豚草种子发芽和幼苗生长产生不同的影响。内生真菌发酵液处理后的种子仍然保持较高程度的活力;不同内生真菌发酵液处理后,有活力的种子维持在50%—87.5%之间,均高于(或等于)清水处理的种子,说明内生真菌代谢产物只是抑制种子的发芽,但并不导致种子的腐烂和死亡。这些研究结果初步显示种子携带的内生真菌可能在豚草入侵生物学中发挥重要的作用。     

Effect of Microbial Inoculants on the Indigenous Actinobacterial Endophyte Population in the Roots of Wheat as Determined by Terminal Restriction Fragment Length Polymorphism

The effect of single actinobacterial endophyte seed inoculants and a mixed microbial soil inoculant on the indigenous endophytic actinobacterial population in wheat roots was investigated by using the molecular technique terminal restriction fragment length polymorphism (T-RFLP). Wheat was cultivated either from seeds coated with the spores of single pure actinobacterial endophytes of Microbispora sp. strain EN2, Streptomyces sp. strain EN27, and Nocardioides albus EN46 or from untreated seeds sown in soil with and without a commercial mixed microbial soil inoculant. The endophytic actinobacterial population within the roots of 6-week-old wheat plants was assessed by T-RFLP. Colonization of the wheat roots by the inoculated actinobacterial endophytes was detected by T-RFLP, as were 28 to 42 indigenous actinobacterial genera present in the inoculated and uninoculated plants. The presence of the commercial mixed inoculant in the soil reduced the endophytic actinobacterial diversity from 40 genera to 21 genera and reduced the detectable root colonization by approximately half. The results indicate that the addition of a nonadapted microbial inoculum to the soil disrupted the natural actinobacterial endophyte population, reducing diversity and colonization levels. This was in contrast to the addition of a single actinobacterial endophyte to the wheat plant, where the increase in colonization level could be confirmed even though the indigenous endophyte population was not adversely affected.     

Enhanced Cd extraction of oilseed rape (Brassica napus) by plant growth-promoting bacteria isolated from Cd hyperaccumulator Sedum alfredii Hance

Four plant growth-promoting bacteria (PGPB) were used as study materials, among them two heavy metal-tolerant rhizosphere strains SrN1 (Arthrobacter sp.) and SrN9 (Bacillus altitudinis) were isolated from rhizosphere soil, while two endophytic strains SaN1 (Bacillus megaterium) and SaMR12 (Sphingomonas) were identified from roots of the cadmium (Cd)/zinc (Zn) hyperaccumulator Sedum alfredii Hance. A pot experiment was carried out to investigate the effects of these PGPB on plant growth and Cd accumulation of oilseed rape (Brassica napus) plants grown on aged Cd-spiked soil. The results showed that the four PGPB significantly boosted oilseed rape shoot biomass production, improved soil and plant analyzer development (SPAD) value, enhanced Cd uptake of plant and Cd translocation to the leaves. By fluorescent in situ hybridization (FISH) and green fluorescent protein (GFP), we demonstrated the studied S. alfredii endophytic bacterium SaMR12 were able to colonize successfully in the B. napus roots. However, all four PGPB could increase seed Cd accumulation. Due to its potential to enhance Cd uptake by the plant and to restrict Cd accumulation in the seeds, SaMR12 was selected as the most promising microbial partner of B. napus when setting up a plant–microbe fortified remediation system.     

Studies on Endophytic Colonization Ability of Two Upland Rice Endophytes, <Emphasis Type="Italic">Rhizobium</Emphasis> sp. and <Emphasis Type="Italic">Burkholderia</Emphasis> sp., Using Green Fluorescent Protein Reporter

Colonization ability of the two endophytic bacteria, isolated from surface sterilized roots of upland cultivated rice viz., Rhizobium sp. and Burkholderia sp., was compared after genetically tagging them with a constitutively expressing green fluorescent protein gene (gfp/gusA). Confocal laser scanning microscopy (CLSM) of gnotobiotically grown seedlings of Narendradhan 97, inoculated with gfp/gusA-tagged endophytes, revealed that both Rhizobium sp. and Burkholderia sp. colonized the intercellular spaces in the root cortex when inoculated separately. Colonization by gfp/gusA-tagged Rhizobium sp. was severely inhibited when co-inoculated with an equal number (10⁶ cfu ml⁻¹) of wild type Burkholderia sp. Burkholderia sp. was a more aggressive endophytic colonizer of rice than Rhizobium sp. The potential of using gfp/gusA reporter and CLSM as tools in evaluating competitive ability of colonization among endophytes is demonstrated in this study.     

Endophytic colonization ability of two deep-water rice endophytes, Pantoea sp. and Ochrobactrum sp. using green fluorescent protein reporter

Colonization ability of the two endophytic bacteria, isolated from surface sterilized seeds of Jaisurya variety of deep-water rice viz., Pantoea sp. and Ochrobactrum sp., was compared after genetically tagging them with a constitutively expressing green fluorescent protein gene (gfp). Confocal laser scanning microscopy (CLSM) of hydroponically grown seedlings of Jaisurya rice, inoculated with gfp-tagged endophytes, revealed that both Pantoea sp. and Ochrobactrum sp. colonized the intercellular spaces in the root cortex when inoculated separately. Colonization by gfp-tagged Ochrobactrum sp. was severely inhibited when co-inoculated with an equal number (10(5) c.f.u. ml(-1)) of wild type Pantoea sp., but the converse was not true. Pantoea sp. was a more aggressive endophytic colonizer of its host than Ochrobactrum sp. The potential of using GFP reporter and CLSM as tools in evaluating competitive ability of colonization among endophytes is herewith demonstrated.     

Identification and characterization of bacterial endophytes of rice

We isolated seven different bacteria from rice seedlings grown from surface sterilized seeds. Three were associated with the rice seed husk and the other four were growing endophytically within the seed. Microscopic studies revealed that the endophytes were concentrated in the root stele region. Some of the bacteria exhibited strong anti-fungal activity against Rhizoctonia solani, Pythium myriotylum, Guamannomyces graminis and Heterobasidium annosum.     

Vertical transmission of fungal endophytes is widespread in forbs

To date, it has been thought that endophytic fungi in forbs infect the leaves of their hosts most commonly by air‐borne spores (termed “horizontal transmission”). Here, we show that vertical transmission from mother plant to offspring, via seeds, occurs in six forb species (Centaurea cyanus, C. nigra, Papaver rhoeas, Plantago lanceolata, Rumex acetosa, and Senecio vulgaris), suggesting that this may be a widespread phenomenon. Mature seeds were collected from field‐grown plants and endophytes isolated from these, and from subsequent cotyledons and true leaves of seedlings, grown in sterile conditions. Most seeds contain one species of fungus, although the identity of the endophyte differs between plant species. Strong evidence for vertical transmission was found for two endophyte species, Alternaria alternata and Cladosporium sphaerospermum. These fungi were recovered from within seeds, cotyledons, and true leaves, although the plant species they were associated with differed. Vertical transmission appears to be an imperfect process, and germination seems to present a bottleneck for fungal growth. We also found that A. alternata and C. sphaerospermum occur on, and within pollen grains, showing that endophyte transmission can be both within and between plant generations. Fungal growth with the pollen tube is likely to be the way in which endophytes enter the developing seed. The fact that true vertical transmission seems common suggests a more mutualistic association between these fungi and their hosts than has previously been thought, and possession of endophytes by seedling plants could have far‐reaching ecological consequences. Seedlings may have different growth rates and be better protected against herbivores and pathogens, dependent on the fungi that were present in the mother plant. This would represent a novel case of trans‐generational resistance in plants.     

Enhancement of the efficiency of Cd phytoextraction using bacterial endophytes isolated from Chromolaena odorata,a Cd hyperaccumulator

Phytoextraction is a technique using a hyperaccumulator to remove heavy metals from soil. The efficiency of heavy metal uptake can be enhanced by the inoculation of endophytes. In this study, we isolated and identified 23 endophytes from Chromolaena odorata, a cadmium (Cd) hyperaccumulator that consisted of 19 bacteria, 2 actinomycetes and 2 fungi. All bacteria and fungi could produce at least 1 plant growth promoting factors. However, only 4 bacterial isolates; Paenibacillus sp. SB12, Bacillus sp. SB31, Bacillus sp. LB51, and Alcaligenes sp. RB54 showed the highest minimum inhibitory concentration (MIC) value (2.9 mM), followed by Exiguobacterium sp.RB51 (1.7 mM). Then, these 5 high-MIC bacteria and 1 low-MIC bacterium, Bacillus sp. LB15 were inoculated onto sunflower grown in soil supplemented with 250 mg/kg of Cd. After 60 days, all inoculated plants accumulated significantly higher Cd concentration than the non-inoculated counterparts, and those inoculated with strain LB51 showed the highest Cd accumulation and growth. Interestingly, strain LB15 with low MIC also enhanced Cd accumulation in plants. The results suggest that these bacteria, particularly strain LB51, could be applied to improve Cd accumulation in plants, and that bacteria with low MIC also have the potential to enhance the efficiency of phytoextraction.     

湖北烟草内生真菌生物多样性和种群结构分析

【目的】研究传统药用植物烟草(Nicotiana tabacum L.)内生真菌的丰富度,揭示其种群多样性和群落结构,为烟草内生真菌资源的有效利用奠定基础。【方法】采用组织分离法进行烟草内生真菌的分离,通过形态学和分子生物学相结合的方法进行菌株分类鉴定,以香农多样性指数及相对分离频率反映内生真菌物种多样性及分布规律。【结果】从不同组织部位、不同生长时期、不同海拔样地的健康烟草中共分离获得539株内生真菌,根据r DNA-ITS系统发育分析鉴定为31属73种,香农多样性指数为2.78,曲霉属Aspergillus和镰孢属Fusarium为优势菌群,其相对分离频率分别为22.63%和12.99%。其分布规律表现为茎部内生真菌的多样性高于叶部和根部;随着生育期的延长,内生真菌多样性逐步增多;随着海拔高度升高,内生真菌的种类和数量呈现降低的趋势。【结论】烟草内生真菌具有丰富的生物多样性,其分布表现出组织、生长时期、海拔高度专化性。阐明内生真菌在烟草中的分布规律,可以为烟草内生真菌在农业生产领域的开发应用提供科学依据。