Mycorrhizal symbioses found in roots of fern and its relatives in Korea

Mycorrhizal symbioses were found in the roots of 45 out of 59 species of pteridophytes collected in Korea. The mycorrhizal fungi were colonized in the root cortical cells, primarily in terrestrial species, but rarely in epiphytic or aquatic pteridophytes. Mycorrhizae that are typically found in orchid colonized the roots of the epiphytic pteridophytes, but not in other species. These were the first observations of orchid mycorrhizae in pteridophytes. Arbuscular mycorrhizal fungi were examined after staining, then confirmed with PCR, using a specific primer. This is the first report of arbuscular mycorrhizal colonization in the roots of pteridophyte species in Asia.     

MYCORRHIZAE IN HAWAIIAN ANGIOSPERMS: A SURVEY WITH IMPLICATIONS FOR THE ORIGIN OF THE NATIVE FLORA

Endemic, indigenous, naturalized and cultivated angiosperms growing in a variety of habitats in Hawaii were examined for mycorrhizae. Of 147 species (representing 61 families) examined, 122 were mycorrhizal, and 98% of the latter formed vesicular-arbuscular mycorrhizae (VAM). Ericoid, orchid, and ectomycorrhizae also were found. Mycorrhizae were most frequent in endemic species (90.3%) and least in indigenous species (71.9%). The incidence of mycotrophy in Hawaiian endemic species was significantly greater than in mainland species. In addition, VAM often were found in species belonging to families that typically lack mycorrhizae (Aizoaceae, Brassicaceae, Caryophyllaceae, Cyperaceae, Hydrophyllaceae, Juncaceae, Pandanaceae, and Urticaceae). Naturalized weedy species were highly mycorrhizal. The high incidence of mycorrhizae in endemic species suggests that VAM fungi and obligately mycotrophic plant species may have been present in the Hawaiian Islands from the earliest stages of the development of the angiosperm flora.     

MYCORRHIZAE IN RECENT VOLCANIC SUBSTRATES IN HAWAII

Plants colonizing 8- and 14-year-old lava flows, a 28-year-old cinder fall, a 137-year-old volcanic soil, and a geothermic volcanic soil were sampled for mycorrhizae. Vesicular arbuscular mycorrhizae were present in all sites, and the frequency of occurrence and intensity of root colonization increased with increasing age of the site. In the youngest site, 57% of the sampled species were mycorrhizal, and this increased to 84% in the cinder fall and 100% in the old soil. Orchid and ericoid mycorrhizae also were present in some sites. Native Hawaiian species tended to more frequently form mycorrhizae and have more intense mycorrhizal infection than did alien species. Plant succession on the Hawaiian volcanic sites differed somewhat from a predictive model in the lack of dominance by nonmycotrophic species in the early seral stages. The difference apparently results from 1) the arrival of mycorrhizal fungi soon after the volcanic substrates cool and 2) the paucity of nonmycotrophic species available to invade very recent volcanic sites.     

Distribution of vesicular-arbuscular mycorrhizae in the plants and rhizosphere soils of the tropical plains,Tamil Nadu,India

We examined 737 plant species from 121 families of angiosperms and four species of pteridophytes for mycorrhizal association. Only 372 species showed infection. Mycorrhizal colonization was recorded in 49% of the total flora. The quantum of colonization ranged from 10% to 90%. In all, 35 species exhibited mycorrhizal colonization higher than 75%. Of the four pteridophytes, Isoetes coromandelina showed mycorrhizal colonization by Entrophospora schenckii and Glomus aggregation in its rhizosphere. For the first time in India, 102 of these species were reported to be mycorrhizal. Glomus fasciculatum (13.8%) and G. aggregation (11%) were prevalent in the rhizosphere soils. Acaulospora foveata (0.2%), A. longula (0.5%) and Glomus hoi (0.9%) were the least represented as mycorrhizal spores. A total of 40 vesicular-arbuscular mycorrhizal fungal species belonging to Acaulospora, Entrophospora, Gigaspora, Glomus, Sclerocystis and Scutellospora were isolated from the rhizosphere soils of different ecosystems.     

黄土高原蕨类植物区系特点的初步研究

对黄土高原的蕨类植物区系组成、分类及其特点进行了研究。结果表明,黄土高原有蕨类植物26科、53属、184种及3变种,种类较多的科有蹄盖蕨科（30种）、鳞毛蕨科（26种）、水龙骨科（20种）、铁角蕨科（12种）、卷柏科（12种）、中国蕨科（11种）及裸子蕨科（10种）等。这７科的种类共计１２１种,占本地区总种数的64.71%。种类较多的属有鳞毛蕨属（13种）、郑柏属（12种）、耳蕨属（11种）、铁角蕨属（11种）、蹄盖蕨属（10种）、瓦韦属（10种）、铁线蕨属（9种）及岩蕨属（9种）等。这8属的种类共计85种,占本地区总种数45.46%,黄土高原蕨类植物区系属的地理成分可划分为15个分布区类型。热带、亚热带分布类型的有18属,占总属数的41.86%,北温带及寒带分布类型的有22属,占总属数（世界分布属除外）的51.16%,其中,亚洲分布类型的最多,计有16属,占总属数的37.20%,表明黄封同原蕨类植物区系是温带类型,区系地理成分以华北区蕨类植物为主,同时也集中了华中、华东、东北、西北以及西南的蕨类植物。而中国特有的分布属只有1属。     

Microevolutionary patterns and processes of the Native Hawaiian colonizing fern Odontosoria chinensis (Lindsaeaceae)

Abstract.— The vascular‐plant flora of the Hawaiian Islands is characterized by one of the highest rates of species endemism in the world. Among flowering plants, approximately 89% of species are endemic, and among pteridophytes, about 76% are endemic. At the single‐island level, however, rates of species endemism vary dramatically between these two groups with 80% of angiosperms and only 6% of pteridophytes being single‐island endemics. Thus, in many groups of Hawaiian angiosperms, it is possible to link studies of phylogeny, evolution, and biogeographic history at the interspecific and interisland levels. In contrast, the low level of single‐island species endemism among Hawaiian pteridophytes makes similar interspecific and interisland studies nearly impossible. Higher levels of interisland gene flow may account for the different levels of single‐island endemism in Hawaiian pteridophytes relative to angiosperms. The primary question we addressed in the present study was: Can we infer microevolutionary patterns and processes among populations within widespread species of Hawaiian pteridophytes wherein gene flow is probably common? To address this broad question, we conducted a population genetic study of the native Hawaiian colonizing species Odontosoria chinensis. Data from allozyme analyses allowed us to infer: (1) significant genetic differentiation among populations from different islands; (2) historical patterns of dispersal between particular pairs of islands; (3) archipelago‐level patterns of dispersal and colonization; (4) founder effects among populations on the youngest island of Hawaii; and, (5) that this species primarily reproduces via outcrossing, but may possess a mixed‐mating system.     

The arbuscular mycorrhizas of pteridophytes in Yunnan, southwest China: evolutionary interpretations

 The percentage of arbuscular mycorrhizal pteridophytes among 256 pteridophyte species distributed in Yunnan (southwest China) was found to be lower than that in angiosperms. In the pteridophytes, the occurrence of arbuscular mycorrhizas was low in sporophytes of fern-allies and leptosporangiates, whereas in the eusporangiates it was relatively high. From the standpoint of mycotrophism, the evolutionary trend in the Filicineae may be from constantly mycorrhizal to facultative mycorrhizal and finally to nonmycorrhizal plants. Accepted: 21 September 2000     

VESICULAR-ARBUSCULAR MYCORRHIZAE IN HAWAIIAN ERICALES

Vesicular-arbuscular mycorrhizae (VAM) are reported for the first time in four species of Hawaiian Ericales, Vaccinium calycinum, V. dentatum, and V. reticulatum of the Ericaceae and Styphelia tameiameiae of the Epacridaceae. The coarse roots (> 1.5 mm diam) of many specimens were densely colonized by VAM fungi, with up to 90% of the length of roots containing arbuscules, vesicles, coils, and internal hyphae. Spores of an undescribed Glomus sp. were associated with two species of Vaccinium. The hair roots of all species bore the ericoid mycorrhizae typical of certain families of this order. The high frequency of VAM in Hawaiian populations of Ericales suggests that ancestral Ericales possessed the capacity to form both VA and ericoid mycorrhizae. An evolutionary sequence of mycorrhizal dependency in the Ericales is presented.     

大兴安岭落叶松林丛枝菌根真菌多样性

对大兴安岭落叶松林17个科26种植物丛枝菌根(AM)定居情况和丛枝菌根真菌(AMF)多样性进行了调查。在26种植物根样中形成典型AM定居的有23种,占88.46%。菌根侵染率为0～78.7%,平均为21.69%。在26种植物根样中,4种植物形成重楼型(Par-is-type)AM,占15.38%;10种植物形成疆南星型(Arum-type)AM,占38.46%;9种植物形成中间型(Intermediatetype)AM,占34.62%,3种植物未能形成AM菌根,占11.54%。从23种植物根围土样中分离到50种AMF,分属于5个属,其中无梗囊霉属(Acaulospora)24种占48%;球囊霉属(Glomus)19种占38%;内养囊霉属(Entrophospora)5种占10%;原囊霉属(Archaeospora)1种占2%;巨孢囊霉属(Gigaspora)1种占2%。Acaulospora和Glomus2属真菌在大兴安岭落叶松林土壤中占绝对优势;尼氏无梗囊霉(A.nocolsonii)和幼套球囊霉(G.etunicatum)是优势种。植物根围土壤中AMF的孢子密度平均为68.94个.100g-1风干土;AM...     

Nuclear DNA C-values in 30 species double the familial representation in pteridophytes

Nuclear DNA C-values and genome size are important biodiversity characters with fundamental biological significance. Yet C-value data for pteridophytes, a diverse group of vascular plants with approx. 9000 extant species, remain scarce. A recent survey by Bennett and Leitch (2001, Annals of Botany 87: 335-345) found that C-values were reported for only 48 pteridophyte species. To improve phylogenetic representation in this group and to check previously reported estimates, C-values for 30 taxa in 17 families were measured using flow cytometry for all but one species. This technique proved generally applicable, but the ease with which C-value data were generated varied greatly between materials. Comparing the new data with those previously published revealed several large discrepancies. After discounting doubtful data, C-values for 62 pteridophyte species remained acceptable for analysis. The present work has increased the number of such species' C-values by 93 %, and more than doubled the number of families represented (from 10 to 21). Analysis shows that pteridophyte C-values vary approx. 450-fold, from 0-16 pg in Selaginella kraussiana to 72.7 pg in Psilotum nudum var. gasa. Superimposing C-value data onto a robust phylogeny of pteridophytes suggests some possible trends in C-value evolution and highlights areas for future work.     

Mycorrhizal status of epiphytes in Malaysian oil palm plantations

Epiphytic plants were collected from four oil palm plantations in Peninsular Malaysia and their mycorrhizal status determined. Conspecific plants with a terrestrial habit (16 species) and rhizosphere soils were also examined for mycorrhizal colonization and glomalean fungi, respectively. Twelve species of glomalean fungi were recovered from the four oil palm plantation soils. Of the 29 epiphytic species in 16 families belonging to the bryophytes, pteridophytes and angiosperms, only four species of angiosperms that were facultative epiphytes and a hemiepiphyte growing within 0.4 m of ground level had vesicular-arbuscular mycorrhizal (VAM) fungi. Bioassays of organic debris from oil palm trunks did not produce vesicular-arbuscular mycorrhizas on maize. Six epiphytic species grown in the greenhouse in pots containing oil palm rhizosphere soils rooted and had VAM fungi and thus may be facultative epiphytes. Five other epiphyte species failed to grow in pots and are probably obligate epiphytes. Seven epiphyte species that established themselves in pots failed to form vesicular-arbuscular mycorrhizas.     

Effects of mycorrhizae on growth and demography of tallgrass prairie forbs

The effects of arbuscular mycorrhizal (AM) symbiosis on ramet and genet densities, vegetative growth rates, and flowering of three forb species were studied in native tallgrass prairie in northeastern Kansas. Mycorrhizal activity was experimentally suppressed for six growing seasons on replicate plots in an annually burned and an infrequently burned watershed with the fungicide benomyl. Benomyl reduced mycorrhizal root colonization to an average of 4.2%, approximately a two-thirds reduction relative to controls (13.7% colonization). Mycorrhizae influenced the population structure of these forbs. Although mycorrhizal suppression had no long-term effect on genet densities and no effect on ramet survivorship throughout the growing season, the number of ramets per individual was significantly increased such that ramet densities of all three species were approximately doubled in response to long-term mycorrhizal suppression. Effects of mycorrhizae on ramet growth and reproduction varied among species. Ramet growth rates, biomass, and flowering of Salvia azurea were greater in plots with active mycorrhizal symbiosis, whereas mycorrhizae reduced ramet growth rates and biomass of Artemesia ludoviciana. Aster sericeus ramet growth rates and biomass were unaffected by the fungicide applications, but its flowering was reduced.The pattern of responses of these three species to mycorrhizae differed considerably between the two sites of contrasting fire regime, indicating that the interaction of fire-induced shifts in resource availability and mycorrhizal symbiosis together modulates plant responses and the intensity and patterns of interspecific competition between and among tallgrass prairie grass and forb species. Further, the results indicate that effects of mycorrhizae on community structure are a result of interspecific differences in the balance between direct positive effects of the symbiosis on host plant performance and indirect negative effects mediated through altered competitive interactions.     

Mycorrhizal colonizations of ferns and lycophytes on the island of La Réunion in relation to nutrient availability

Very little is known about the degree and ecological correlates of mycorrhization of lycophytes and ferns, although mycorrhizae are believed to be crucial for the majority of land plants. We screened the degree of mycorrhizal colonization for all 75 fern species recorded in nine survey plots across a wide range of soil conditions on the island of La Réunion, including five plots on lava flows of different age. Overall, 66% of all samples had mycorrhizae, but ground-dwelling species had significantly higher colonization levels (78%) than epiphytes (58%). Among ground-dwelling species, 98% of the individuals belonged to species with mycorrhizae, which was significantly higher than at the species level. Most samples had glomeromycetes as fungal partners, but septate endophytes were found in 41% of the colonized samples. While we found no significant relationship between the percentage of fern species with mycorrhizae per plot and seven ecological parameters, the percentage of fern individuals with mycorrhizal colonizations per plot significantly increased on shallow soils with high pH values and high base-saturation. This supports the idea that mycorrhizal colonizations confer an ecological advantage to colonized individuals, and that this advantage is more pronounced on nutrient-deficient sites. Our study thus provides evidence for an ecological advantage of mycorrhizae for ferns, but raises the question why, despite this advantage, species level mycorrhization among ferns (68%) is so much lower than the average for land plants (85%).     

Arbuscular mycorrhizal colonization in field-collected terrestrial cordate gametophytes of pre-polypod leptosporangiate ferns (Osmundaceae,Gleicheniaceae, Plagiogyriaceae,Cyatheaceae)

To determine the mycorrhizal status of pteridophyte gametophytes in diverse taxa, the mycorrhizal colonization of wild gametophytes was investigated in terrestrial cordate gametophytes of pre-polypod leptosporangiate ferns, i.e., one species of Osmundaceae (Osmunda banksiifolia), two species of Gleicheniaceae (Diplopterygium glaucum, Dicranopteris linearis), and four species of Cyatheales including tree ferns (Plagiogyriaceae: Plagiogyria japonica, Plagiogyria euphlebia; Cyatheaceae: Cyathea podophylla, Cyathea lepifera). Microscopic observations revealed that 58 to 97 % of gametophytes in all species were colonized with arbuscular mycorrhizal (AM) fungi. Fungal colonization was limited to the multilayered midrib (cushion) tissue in all gametophytes examined. Molecular identification using fungal SSU rDNA sequences indicated that the AM fungi in gametophytes primarily belonged to the Glomeraceae, but also included the Claroideoglomeraceae, Gigasporaceae, Acaulosporaceae, and Archaeosporales. This study provides the first evidence for AM fungal colonization of wild gametophytes in the Plagiogyriaceae and Cyatheaceae. Taxonomically divergent photosynthetic gametophytes are similarly colonized by AM fungi, suggesting that mycorrhizal associations with AM fungi could widely occur in terrestrial pteridophyte gametophytes.     

Arbuscular mycorrhiza formation in cordate gametophytes of two ferns, Angiopteris lygodiifolia and Osmunda japonica

Mycorrhizal symbiosis is common among land plants including pteridophytes (monilophytes and lycophytes). In pteridophytes with diplohaplontic life cycle, mycorrhizal formations were mostly reported for sporophytes, but very few for gametophytes. To clarify the mycorrhizal association of photosynthetic gametophytes, field-collected gametophytes of Angiopteris lygodiifolia (Marattiaceae, n = 52) and Osmunda japonica (Osmundaceae, n = 45) were examined using microscopic and molecular techniques. Collected gametophytes were mostly cut into two pieces. One piece was used for light and scanning microscopic observations, and the other for molecular identification of plant species (chloroplast rbcL sequences) and mycorrhizal fungi (small subunit rDNA sequences). Microscopic observations showed that 96 % (50/52) of Angiopteris and 95 % (41/43) of Osmunda gametophytes contained intracellular hyphae with arbuscules and/or vesicles and fungal colonization was limited to the inner tissue of the thick midribs (cushion). Fungal DNA analyses showed that 92 % (48/52) of Angiopteris and 92 % (35/38) of Osmunda have sequences of arbuscular mycorrhizal fungi, which were highly divergent but all belonged to Glomus group A. These results suggest that A. lygodiifolia and O. japonica gametophytes consistently form arbuscular mycorrhizae. Mycorrhizal formation in wild fern gametophytes, based on large-scale sampling with molecular identification of host plant species, was demonstrated for the first time.     

江西省资溪县马头山蕨类植物区系

马头山蕨类植物区系由 3 0科 62属 1 42种组成。区系地理成份复杂 ,科属的地理成份以热带亚热带性质为主。主要的科是鳞毛蕨科 (2 5种 )、水龙骨科 (1 8种 )、金星蕨科 (1 5种 )、卷柏科 (1 1种 )、蹄盖蕨科 (1 1种 ) ,5科占总种数 5 6.3 4%。主要的属是鳞毛蕨属 (1 6种 )、卷柏属 (1 1种 )、凤尾蕨属 (8种 )、铁角蕨属 (8种 )、复叶耳蕨属 (5种 )、假瘤蕨属 (4种 )占总种数 3 6.62 %。马头山蕨类植物区系属的地理成份可分为 8个 ,主要是泛热带 (1 9属 )、热带亚洲 (7属 )、世界广布 (1 9属 )成份 ,占总属数 72 .5 8%。而种的地理成份则以亚热带山地成份为主 ,本区东亚成份突出 ,加上中国特有成份共占总种数的 66.2 1 %。显然应是东亚植物区系的一部分。掌叶假瘤蕨为江西省首次发现。     

广东从化陈禾洞省级自然保护区维管植物区系研究

在野外调查及查阅相关资料的基础上,对广东从化陈禾洞省级自然保护区植物区系进行研究。结果表明:(1)该区植物资源丰富,共有野生维管植物193科627属1139种(包括种下等级)。其中,蕨类植物36科66属119种,裸子植物7科8属9种,被子植物150科528属1011种(双子叶植物130科417属838种,单子叶植物20科111属173种)。(2)该区种子植物科、属优势现象明显,以菊科Asteraceae、禾本科Poaceae及茜草科Rubiaceae为主。在科属的组成上较为分散,主要以少寡种的科、属为主,分别占67.88%、91.7%。(3)该区蕨类植物在属的组成上也较为分散,以5个种以下的属为主,占比为93.94%。(4)该区植物区系成分复杂,在科级水平上,种子植物有8个分布区类型及5个变型,热带分布类型成分有80个科,占总科数的50.96%,而蕨类植物有5个分布区类型,热带成分的科有23个,占蕨类总科数的63.89%;在属级水平上,种子植物有13个分布区类型及16个变型,热带成分有365属,占总属数的68.10%,而蕨类植物有7个类型及1个变型,热带分布类型成分有40属,占蕨类植物总属数的60.61%。     

Arbuscular Mycorrhizae in association with aquatic and marshy plant species in Goa,India

Of the 20 plant species of hydrophytes screened for Arbuscular Mycorrhizal (AM) fungal root colonization, 10 aquatic plants (out of 14 species) and five marshy plants (out of six species) were found to be mycorrhizal, while the remaining species were non mycorrhizal. Vesicular colonization occurred in 12 plant species while arbuscular colonization was restricted to only three plant species. A rooted submerged pteridophyte viz., Isoetes coromandelina L. was found to be mycorrhizal exhibiting vesicular colonization. In all, two genera viz., Glomus and Scutellospora, the former being dominant, were recorded. The most common AM fungal species Glomus claroideum was recovered from 14 plant species.     

中国蕨类植物细胞分类学研究概况

中国蕨类植物类群十分丰富,由63科230属约2600种组成,其中约有10％的种类为中国特有。迄今为止,中国蕨类植物进行过染色体计数的种类约有395种,仅占中国蕨类植物总数的15％,其中48％为多倍体。本文对中国蕨类植物细胞分类学研究的历史和现状进行了综合评述。文中论述了蕨类植物染色体数目和染色体基数在系统学上的应用以及蕨类植物染色体组型分析、多倍化、无融合生殖、多倍体复合体及网状进化的研究概况。中国20多年的蕨类植物细胞分类学研究表明,蕨类植物的染色体数目、基数、组型分析、多倍化及其繁殖方式对蕨类植物的分类、起源和演化的研究都有重要作用,对种及种复合体的鉴定、科属的划分也有重要的参考价值。并对中国蕨类植物细胞分类学研究提出了一些建议。     

湖北恩施地区蕨类植物区系研究

蕨类植物是森林植被中草本层的重要组成部分,对森林的生长发育有重大影响。本研究在搜集文献、野外调查和采集标本的基础上,对湖北恩施地区蕨类植物区系成分及特点进行研究。结果显示:(1)恩施地区蕨类植物共有39科96属380种,其中中国特有种106种;该地区蕨类植物起源古老,物种分化水平较高,优势科属明显、物种丰富、组成多样,是蕨类植物物种多样性的典型代表地区之一。(2)该地区稀子蕨属、荚果蕨属、黔蕨属和骨牌蕨属种类齐全、分布广泛,是这些属的分化和分布中心。(3)该地区蕨类植物生活类型齐全,以土生为主(占81.36%)。(4)恩施地区在中国蕨类植物地理区系中占有重要地位,该地区蕨类植物科属以泛热带区系成分相对较多,总体偏热带区系成分;物种以温带亚洲、东亚和中国特有分布型为主(占60.79%),具有显著的亚热带性质。(5)恩施蕨类植物区系与其他地区联系广泛,过渡性比较明显,尤其与四川地区联系紧密。