Low Molecular Weight Carbohydrate Patterns in Geographically Different Isolates of the Eulittoral Red Alga Bostrychia tenuissima from Australia

Sixteen isolates of the red alga, Bostrychia tenuissima King et Puttock, from New South Wales, Victoria and South Australia were cultured in the laboratory and analysed for low molecular weight carbohydrates using ¹³C-NMR and HPLC techniques. All populations south of 34 °S contain D-sorbitol in combination with the heteroside digeneaside. The isolates north of 34° S lack digeneaside, but contain D-sorbitol and, in addition, an isomeric form D-dulcitol. Moreover, the ¹³C-NMR spectra showed an unknown metabolite which was only measured in combination with digeneaside. While in the strains south of 34 °S digeneaside and the unknown compound occur in small quantities and remained unchanged with increasing salinities (5–60 ppt), the relatively high D-sorbitol contents strongly increased under hypersaline conditions. In the populations north of 34 °S both the concentrations of D-sorbitol and D-dulcitol increased with increasing salinity. These data demonstrate the important role of polyols in the osmotic acclimation of B. tenuissima. The ecological and/or biological factors controlling this geographical pattern of metabolite content are not known. However, the different carbohydrate patterns within B. tenuissima are considered as indicators of the development of physiological ecotypes.     

Observations on Bostrychia radicosa comb. nov. (Rhodomelaceae, Rhodophyta)

Only two genera in the Rhodomelaceae share the morphological character of transverse division of periaxial cells into two or more tier cells in which the pit connection is retained between the lower cell and the axial cell: Bostrychia and Rhodolachne. One species, Rhodolachne radicosa Itono, has been reported from mangroves, a common habitat for Bostrychia. Many collections of an entity similar to Rhodolachne radicosa have been made from localities around the Indo‐Pacific. Culture observations show a Polysiphonia‐type sexual life history in Malaysia and New Caledonia isolates that produce self‐compatible bisexual gametophytes. The New Caledonia isolate also has unisexual gametophytes. An isolate from New South Wales (Australia) reproduces asexually through successive generations of tetrasporophytes. The Thailand isolate has successive generations of mixed‐phase tetrasporophytes. The tetrasporangial stichidia also bear male spermatangial sectors, but female structures are lacking. Western Australia and Madagascar isolates do not reproduce in culture. Molecular evidence, based on sequencing of the rbcL and the large subunit ribosomal RNA genes, shows that these isolates belong to the genus Bostrychia. Low molecular weight carbohydrate analysis reveals high levels of digeneaside in all isolates. The sugar hexitol sorbitol, an osmolyte characteristic of Bostrychia, occurs in all isolates, whereas the Madagascar and New Caledonia isolates have very low levels of dulcitol. Molecular, low molecular weight carbohydrate and morphological evidence show that Rhodolachne radicosa belongs within the genus Bostrychia. We transfer Rhodolachne radicosa to Bostrychia radicosa (Itono) West, Zuccarello and Hommersand.     

Distribution of alditols in the genus Bostrychia

Several species of the red algal genus Bostrychia were investigated for the presence of low-molecular weight carbohydrates constituting their specific assimilate pattern. All species were found to contain remarkable amounts of two hexitols, dulcitol and sorbitol. The results are discussed with emphasis on the chemotaxonomic implications.     

A new unusual low molecular weight carbohydrate in the red algal genus <Emphasis Type="Italic">Hypoglossum</Emphasis> (Delesseriaceae,Ceramiales) and its possible function as an osmolyte

The low molecular weight carbohydrates in various species of the red algal genus Hypoglossum (Delesseriaceae, Ceramiales) were analysed using HPLC, ¹H and ¹³C-nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. All specimens contained the heteroside digeneaside which is considered as chemosystematic marker for the Ceramiales. A new HPLC method was developed for the separation and quantification of this compound, and concentrations between 131.6 mmol kg^–1 and 539.6 mmol kg^–1 DW could be measured among the species tested. In addition, during the HPLC analysis another new low molecular weight carbohydrate was detected in two species from The Philippines (H. barbatum) and Western Australia (H . heterocystideum), and its chemical structure elucidated as digalactosylglycerol applying various NMR experiments. The remaining Hypoglossum taxa lack this compound. Although digalactosylglycerol occurred in high concentrations in the range of 221.7 and 438.7 mmol kg^–1 DW in H. barbatum and H . heterocystideum, respectively, it has never been reported for any other algal species before. Therefore, to test the possible physiological function of this unusual carbohydrate as organic osmolyte, H. barbatum was treated with a range of salinities. While the digeneaside content remained almost unchanged, the digalactosylglycerol concentration strongly increased with increasing salinities from 70 mmol kg^–1 DW at 20 psu to 215 mmol kg^–1 DW at 45 psu. In conclusion, while neither published work nor the present study indicate digeneaside to play more than a minor role in osmotic acclimation, the data presented strongly support an osmotic function of digalactosylglyerol.     

Osmoprotectors in some species of Japanese mangrove macroalgae

The macroalgae asSociated with the mangrove vegetation of the Japanese Islands Okinawa, Ishigaki and Iriomote were investigated. The flora includes members of the red algal genera Bostrychia, Caloglossa and Catenella, as well as the brown alga Dictyotopsis propagulifera Troll, which may be considered typical of mangrove forests. The distribution of the low molecular weight carbohydrates sorbitol, dulcitol, mannitol and floridoside was studied in the mangrove algae. Their physiological role as osmoprotectors was assessed by investigating the effect of salinity on the intracellular sorbitol and dulcitol concentration in Bostrychia pinnata J. Tanaka et Chihara and on the mannitol content in D. propagulifera. In both species the polyol values increased with increasing salinity.     

Ultraviolet sunscreen compounds in epiphytic red algae from mangroves

Epiphytic red algae of the order Ceramiales from mangroves and salt marshes (nine species from Bostrychia, three from Stictosiphonia and four from Caloglossa) produce varying levels of the UV-absorbing compounds mycosporine-glycine, shinorine, porphyra-334, palythine, asterina-330 and palythinol, a suite of substances chemically assigned as mycosporine-like amino acids (MAAs). Mean MAA levels varied from 0.02 to 12.8 mg g^–1 DW in field-collected and laboratory cultured specimens. While in field samples of Bostrychia montagneiHarvey, Bostrychia radicans (Montagne) Montagne and Caloglossa apomeiotica J.West et G.Zuccarello MAA concentrations were generally higher compared to cultured plants of the same taxa, Bostrychia tenella(Lamouroux) J.Agardh did not show such a difference. Catenella caespitosa (Withering) L.Irvine, Catenella impudica (Montagne) J.Agardh and Catenella nipae Zanardini (Gigartinales, Caulacanthaceae) produce two novel UV-absorbing compounds: MAA-1 (1.4–4.3 mg g ^–1 DW) and MAA-2 (0.1–1.0 mg g^–1 DW), which absorb at 334 nm and 320 nm, respectively. In laboratory culture of Bostrychia moritziana when photosynthetically active radiation (PAR) was increased from 20 to 40 mol photons m^–2 s^–1, the total level of palythinol increased by 85% (from 2.0 to 3.7 mg g^–1 DW). In a culture of Caloglossa leprieurii when PAR was increased from 40 to 80 mol m^–2 s^–1the porphyra-334 content increased by 77% (from 3.1 to 5.5 mg g^–1 DW). Extremely high MAA contents of >30 mg g^–1 DW were detected in mature tetrasporangial sori prepared from two isolates of laboratory-cultured reproductive Caloglossa apomeiotica compared to vegetative plants (about 10 mg MAAs g^–1 DW) indicating tetraspores loaded up with UV-sunscreens. All data demonstrate that mangrove red algae contain high MAA concentrations, particularly the reproductive structures, and hence these compounds may act as biochemical photoprotectants against exposure to UV-radiation.     

基于山地蜂蜜花粉组成的中华蜜蜂传粉多样性研究

中华蜜蜂为多种植物传粉,具有重要的生态服务价值。为进一步了解中华蜜蜂选择蜜粉源植物的多样性与特征,采用聚合酶链式反应(PCR)、DNA条形码、高通量测序等技术,研究了源自陕西宝鸡、贵州望谟和广西凤山蜂巢蜜中的花粉来源。通过对样品花粉rbcL基因片段扩增及测序、分析,发现各样本间可操作分类单元(OTU)水平上蜜粉源植物Alpha多样性指数无显著差异,同一地点样品不同重复间存在较高的相关性,而不同地区样本相关性较低。三地共鉴定出27目46科71属82种蜜粉源植物,其中宝鸡市、望谟县、凤山县样本中分别鉴定出57种、30种和40种,各地蜜粉源植物的物种组成存在较大差异。这些蜜粉源植物中,菊目植物种类最多,其次为毛茛目,分别有12种和7种。其中草本植物和木本植物(含乔木、灌木和木质藤本等)分别有44种和38种。研究对蜜粉源植物花序特点进行了分析,但并未发现相关性状对中华蜜蜂选择具有的影响。从属的区系成分分析,总体上温带分布区类型的植物属多于热带分布区类型的属,所占比例分别为46.5%和36.6%,但在凤山县样本中出现热带分布区类型多于温带分布区类型的情况。在不同样品中,红足蒿(Artemisia rubripes)、向日葵(Helianthus annuus)、芜青(Brassica rapa)、粗糠柴(Mallotus philippensis)、枇杷(Eriobotrya japonica)等分别占有一定优势,其与中华蜜蜂的关系值得进一步研究。根据蜜粉源植物的系统进化关系,中华蜜蜂访问的蜜粉源植物处于不同进化地位的分支,其中在菊类分支和蔷薇类分支比较集中。研究揭示了中华蜜蜂传粉植物组成特点,为进一步认知中华蜜蜂传粉服务功能的重要性提供依据。     

山西蟒河国家级自然保护区猕猴食源植物区系特征

于2012~2013年,以样带法、样方法和无样地法相结合,分4次对蟒河国家级自然保护区猕猴栖息地食源植物种类进行了实地调查,并分析了其区系特征。研究发现:(1)蟒河保护区猕猴栖息地内有维管植物659种,隶属102科374属,其中54科126属261种为猕猴的食源植物,占猕猴栖息地植物科、属、种总数的52.94%、33.69%和39.61%;蔷薇科是食源植物中包含种类最多的科,有16属39种,其次为豆科,含11属23种。(2)蟒河保护区内猕猴食源植物区系特征为:食源植物所在科有6个分布型和2个变型,所在属有13个分布型和6个变型;在属的分布类型中,温带性质分布类型的属占优势,有75个,占总属数的66.96%,其中北温带分布类型的属46个,占总属数的41.07%;热带性质分布类型的属有24个,地中海区、中亚、东亚和中国特有分布成分的属共有13个,分别占总属数的21.43%和11.61%,说明蟒河保护区内猕猴食源植物区系为暖温带性质。     

LOW MOLECULAR WEIGHT CARBOHYDRATES OF THE BANGIOPHYCIDAE (RHODOPHYTA)1

In the order Porphyridiales there are three clades based on molecular evidence. These show parallels with the low molecular weight carbohydrate (LMWCs) in different genera. Clade Porphyridiales 1 includes Dixoniella, Glaucosphaera, Rhodella, and one undescribed genus (3987) that all contain mannitol. Clade Porphyridiales 2 comprises taxa of the Stylonematales Rhodosorus and Stylonema species and contains digeneaside and sorbitol, whereas Chroodactylon has only sorbitol. In clade Porphyridiales 3 Flintiella, Porphyridium, and the undescribed genus (3797) all possess only floridoside. In the Erythropeltidales Rhodochaete contains floridoside and digeneaside, Erythrotrichia species contain only floridoside, Sahlingia subintegra has floridoside and traces of D‐floridoside, and Smithora has L‐isofloridoside plus floridoside. In the Compsopogonales Boldia and Compsopogon have only floridoside. Within these genera as presently circumscribed, the LMWCs appear to be a reliable character to supplement the usual cytological characters.     

Polyol metabolism by Rhizobium trifolii.

In Rhizobium trifolii 7000, the polyols myo-inositol, xylitol, ribitol, D-arabitol, D-mannitol, D-sorbital, and dulcitol are metabolized by inducible nicotinamide adenine dinucleotide-dependent polyol dehydrogenases. Five different polyol dehydrogenases were recognized: inositol dehydrogenase, specific for inositil; ribitol dehydrogenase, specific for ribitol; D-arabitol dehydrogenase, which oxidized D-arabitol, D-mannitol, and D-sorbitol; xylitol dehydrogenase, which oxidized xylitol and D-sorbitol; and dulcitol dehydrogenase, which oxidized dulcitol, ribitol, xylitol, and sorbitol. Apart from inositil and xylitol, all of the polyols induced more than one polyol dehydrogenase and polyol transport system, but the heterologous polyol dehydrogenases and polyol transport systems were not coordinately induced by a particular polyol. With the exception of xylitol, all of the polyols tested served as growth substrates. A mutant of trifolii 7000, which was constitutive for dulcitol dehydrogenase, could also grow on xylitol.     

14C-Assimilate pattern and kinetics of photosynthetic 14CO2-assimilation of the marine red alga Bostrychia scorpioides

Summary Occurrence and metabolism of dulcitol and sorbitol in the marine red alga Bostrychia scorpioides (Huds.) Mont. (Ceramiales: Rhodomelaceae) were investigated. Both hexitols are rapidly ¹⁴C-labelled during photosynthesis in a H¹⁴CO₃-seawater medium and are accumulated at comparable rates. The absolute quantity amounts to about 3.2% on a dry weight basis; the percentage of ¹⁴C-labelling after 60 min is 30% for dulcitol and 40% for sorbitol. Additionally small amounts of free [¹⁴C] glucose were found. Pulse labelling experiments and changes in specific activity provide evidence that both hexitols are rapidly available respiratory substrates, which, however, are probably not interconvertible with polymeric compounds. Some chemotaxonomic aspects are discussed.     

Metabolism of dulcitol in Euonymus japonica

Dulcitol-1(6)-¹⁴C was administered to leaves of E. japonica and samples were taken for time periods ranging from 0·5 to 24 hr. For each time period the absolute activity of the glucose, galactose and dulcitol pools was determined. Such studies demonstrated that dulcitol is converted to glucose and galactose. The initial product was glucose, some of which was converted to galactose, glacturonic acid and glucuronic acid. Fractionation of a leaf sample into its pectin, lignin, hemicellulose and α-cellulose components, with subsequent hydrolysis, showed that the dulcitol pool is used in the synthesis of structural carbohydrates. The activity of these fractions was shown to reside in dulcitol, glucose, galactose, galacturonic acid and glucuronic acid residues.     

Characteristic Trichomes and Indumentum Specialization in African and European Parasitic Scrophulariaceae

Trichomes and their distribution patterns have been observed in the aerial parts of plants of the genera Striga, Buchnera, Rhamphicarpa, Euphrasia, Melampyrum and Rhinanthus, using both light (LM) and scanning electron microscopy (SEM). All trichomes belong to the multicellular, uniseriate category and can be classified as glandular and nonglandular types. On nearly all organs, the two types can be observed side by side. Apart from a large group of ubiquitous trichomes, some characteristic trichome types are reported; they are restricted either to chlorophyllous organs (foliage leaves, bracts, calyx and stem) or to the corolla. In some nonglandular trichomes mineral deposits have been found. Other morphological and anatomical trichome features are discussed with regard to their possible function.     

Red Light Effects on Uptake of 14C and 32P into Etiolated Corn Leaf Tissue During Photomorphogenic Leaf Opening

Red light effects on the uptake of ¹⁴C and of ³²P was studied by observing leaf sections from 8-day-old etiolated corn leaves that were placed on various substrates following a brief exposure to red radiant energy. There was a general increase of ¹⁴C uptake over dark levels into all metabolite fractions that were prepared. This is in contrast with results obtained previously in which leaf samples were first floated on substrate and then irradiated (Mitrakos et al. 1967, Price et al. 1965). The latter tests resulted in a general decrease in sugar and starch as well as ¹⁴C content of all fractions. However, under both types of experimental conditions the red light effect manifested itself as an increase in hexosemonophosphate turn-over rate and accumulation of radioactivity in the cell wall polysaccharide fraction. The present data further substantiate the previous work in that they demonstrate the regulatory influence of the hexose pool size on the intermediary metabolism and the manifestation of the phytochrome responses. From the data thus far obtained it cannot be determined as to whether or not phytochrome mediates by controlling phosphorylating activity or through control of specific enzymatic processes that lead to observable cell wall polysaccharide synthesis and leaf unrolling.     

Chloroplast movements in fern leaves: correlation of movement dynamics and environmental flexibility of the species

The movements of chloroplasts in response to varying levels and wavelengths of incident light were investigated in leaves of four fern species: Adiantum capillus-veneris, Adiantum caudatum, Adiantum diaphanum and Pteris cretica. In all of the species studied blue light induced chloroplast redistribution resulting in face and profile patterns that were typical of low and high fluence rates, respectively. Fluence rate response characteristics and the kinetics of transmission changes accompanying these blue-light-induced movements were similar to those observed in the leaves of higher plants. Only in A. capillus-veneris was the distribution of chloroplasts affected by red light. The response was of the weak-light type, irrespective of the light intensity. The most effective fluence rate for red light was found to be below 7·2 μmol m^–2 s^–1 (1 W m^–2). The effect of red light was far-red reversible, indicating phytochrome involvement. Chloroplast responses were more dynamic in A. capillus-veneris and P. cretica, the two species that exhibited higher environmental flexibility.     

EFFECT OF SPECTRAL QUALITY ON GROWTH AND PIGMENTATION OF PICOCYANOBACTERIA1

The influence of spectral quality on growth and pigmentation was compared among five strains of marine and freshwater picocyanobacteria grown under the same photon flux density (28 μE · m^?2·s^?1). Growth and phycoerythrin (PE) concentration per unit carbon increased when marine Synechococcus WH7803 was grown under green light as compared to red light, but no change in phycocyanin concentration occurred. Marine Synechococcus strain 48B66 also showed greater levels of PE when grown under green light than under red light, but no concomitant growth increase occurred. Both strains thus exhibited Group II chromatic adaptation. Additionally, strain 48B66 increased the relative level of phycourobilin compared to phycoerythrobilin when grown under red light. In contrast, both marine and freshwater Synechococcus strains containing no PE showed decreased growth under green light. Chlorophyll a concentrations were greatest or among the greatest in all strains grown under green light. These results suggest that light quality, through its effects on growth rate, may be an important factor controlling the distribution and abundance of the various pigment types of Synechococcus.     

Impact of the salt stress on the photosynthetic carbon flux and C-label distribution within floridoside and digeneaside in Solieria chordalis

The flux of photosynthetic carbon used in the synthesis of low-molecular weight carbohydrates (digeneaside and floridoside) was investigated by ¹³C and ¹H NMR spectroscopy in samples of the red seaweed, Solieria chordalis, incubated at different salinities (22, 34 and 50 psu). Carbohydrates were labelled, by pulse-chase, with the stable isotope ¹³C from NaH¹³CO₃. In vivo NMR analyses carried out with a cryogenic probe optimised for ¹³C detection were performed directly on the living algal tissues to evidence the labelling of the carbohydrates with neither preliminary extraction nor purification step(s). The isotopic enrichment of each compound was determined by high-resolution ¹H and ¹³C NMR spectroscopy. These analyses evidenced different orientations of the flux of the photosynthetic carbon in the algae according to the salt stress. At normal and low salinities, the photosynthetic carbon flux was responsible of 70% and 67% of the floridoside synthetized during the pulse period, respectively, whereas it was only of 30% in the thalli exposed to the high salinity, meaning a biosynthesis of high floridoside amount from endogen source leading to the osmotic regulation. Under normal and hyper-osmotic conditions, the stock of floridoside was used for cellular needs during the chase period, whereas it was not under hypo-osmotic conditions.The characterization of isotopomers composition of floridoside and digeneaside and the analysis of adjacent ¹³C-labelling gives much more details on the effects of salinity on the metabolic pathways leading to the synthesis or the degradation of these molecules. High turnover of floridoside was evidenced at normal salinity during the chase period and products issued from the degradation of floridoside would not be used for the novo biosynthesis. That suggests that synthesis and degradation of floridoside may be realized in two different cellular compartments. The presence of more numerous ¹³C-¹³C blocks in the carbon skeleton of the molecules from the up salt stressed thalli than in those from no salt stressed algae, concomitant with a slower degree of isotopic enrichment of the molecule, provided evidence that the two metabolic pathways (endogen and photosynthetic) may not share the precursor molecules involved in the floridoside synthesis and that these two routes may be totally separate until the constitution of floridoside molecule.     

Phylogeny, Biogeography, and Processes of Molecular Differentiation in Quercus Subgenus Quercus (Fagaceae)

Quercus is one of the most abundant and economically important genera of woody plants in the Northern Hemisphere. To infer phylogenetic relationships within Quercus subgenus Quercus, chloroplast DNA (cpDNA) restriction sites and nucleotide sequences of the internal transcribed spacers (ITS) and the 5.8S coding region of the nuclear ribosomal DNA repeat were obtained for 44 individuals, including 25 species, intraspecific samples, and three outgroups. Separate parsimony analyses of each data set showed that individual gene trees were congruent and often complementary in supporting clades that generally corresponded to previously recognized taxonomic groups. Only one instance of strongly supported gene tree incongruence was detected and this anomalous pattern was explained best by ancient introgression of cpDNA across sectional boundaries. Simultaneous parsimony analysis of the pruned data sets supported the recognition of the strictly Eurasian section Cerris and resolved a novel hypothesis for the major infrageneric groups (Cerris- (Lobatae- (Protobalanus + Quercus sensu stricto))). The biogeographic hypothesis that all major oak lineages evolved locally at middle latitudes within the general distribution of their fossil ancestors was fully supported. This set of relationships also suggested a New World origin for the widespread white oaks of the Northern Hemisphere (section Quercus s. s.). For both data sets, inter- and intraspecific sampling within section Protobalanus showed little correspondence to morphological species. Greater cladistic structure among the samples was obtained by cpDNA restriction sites and two well-delimited plastomes types comprising a total of 15 distinct haplotypes were resolved. Haplotypes of 2 of the peripheral species in this species complex occupy terminal portions of one of the plastome clades, suggesting a more recent origin relative to those of more widespread species. The phylogeography of the two divergent plastome types suggested a north–south pattern, consistent with a Late Tertiary disjunction in the ancestral distribution of section Protobalanus.     

青藏高原东南部察隅河流域种子植物区系研究

在野外植被调查、标本采集和资料查询整理的基础上,汇总了察隅河流域种子植物名录,并对流域内植物物种的组成、优势科属、区系地理成分及性质进行分析。运用R语言在属水平上与其周边16个地区的植物区系进行聚类及主成分分析,探讨察隅河流域种子植物区系与其他区系之间的关系。结果表明：(1)察隅河流域共含种子植物138科、689属、2 771种(含变种),其中裸植子物4科12属56种,被子植物134科677属2 715种,被子植物中双子叶植物112科531属2 270种占绝对优势。(2)区内地理成分联系广泛,科的区系划分除世界分布类型外,热带分布型53科(55.21%),温带分布型43科(44.79%);属的区系划分中所有类型均有分布,温带分布型396属(62.07%),热带分布型230属(36.05%);属的分布型与科相比具有更明显的温带性质;植物种类丰富度高但特有成分低,无特有科,仅含12特有属。(3)流域内植被垂直地带性分布较为明显,保留了较多古老孑遗植物,如裸子植物的西藏红豆杉(Taxus wallichiana)、察隅冷杉(Abies chayuensis)和云南松(Pinus yunnanensis)等;由于青藏高原的上升运动,成为杜鹃花属(Rhododendron)、虎耳草属(Saxifraga)、龙胆属(Gentiana)和报春花属(Primula)等新生高山植物区系成分分化繁衍的摇篮。(4)察隅河植物区系属喜马拉雅山南侧热带成分向温带成分过渡的区系性质,与珠峰自然保护区植物区系更为相似。     

柑橘内生真菌的分离鉴定及其发酵产物对柑橘溃疡病菌的抑制活性

本研究从柑橘抗病品种的健康植株不同组织中分离纯化和鉴定内生真菌,并测定其发酵产物对柑橘溃疡病菌的抑制活性,以明确柑橘抗病品种中内生真菌的组成及其产抗柑橘溃疡病菌活性代谢产物的潜力,为柑橘溃疡病抗菌剂的开发奠定基础。该研究通过组织培养法分离内生真菌,采用形态学和分子生物学方法对其进行鉴定; 基于前期的拮抗预试验结果,选取代表性菌株进行发酵培养,通过乙酸乙酯浸提、真空抽滤、旋转蒸发浓缩制备粗提物; 采用带毒平板涂布法测定不同菌株发酵产物乙酸乙酯提取物对柑橘溃疡病菌的抑制活性。结果表明:(1)共分离得到72株内生真菌,归为2门(Ascomycota、Basidiomycota)、14个属,其中优势属为刺盘孢属(Colletotrichum)、球座菌属(Guignardia)、链格孢属(Alternaria)和镰刀菌属(Fusarium)。(2)不同柑橘品种中内生真菌多样性指数为温州蜜柑(桂林)>沙糖桔(桂林)>沙糖桔(梧州)。(3)不同组织中内生真菌多样性变化因地理位置差异而有所不同,采自桂林的温州蜜柑和沙糖桔均为叶片中的内生真菌的多样性高于枝条,而采自梧州的沙糖桔为叶片中的多样性低于枝条,并且采自梧州的柑橘样品与采自桂林的柑橘样品中的内生真菌相似性低。(4)测定了30株内生真菌乙酸乙酯提取物对柑橘溃疡病菌的抑制活性,其中29株菌株表现出不同程度抑制活性。不同柑橘品种中的优势属的MIC介于0.312 5～10 mg·mL^-1之间,特有属的MIC介于0.156～5 mg·mL^-1,共有属镰刀菌属的MIC介于0.312 5～2.5 mg·mL^-1之间。研究结果表明柑橘抗病品种中内生真菌具有丰富多样性,并且其发酵提取物普遍对柑橘溃疡病菌具有抑制作用。特有属抑菌活性总体优于优势属,共有属镰刀菌属在不同柑橘抗病品种中均具有显著抑菌效果。