Interactions between the soilborne root pathogenPhytophthora nicotianae var.parasitica and the arbuscular mycorrhizal fungusGlomus mosseae in tomato plants

In order to study the influence of Arbuscular Mycorrhiza (AM) on the development of root rot infection, tomato plants were raised with or withoutGlomus mosseae and/orPhytophthora nicotianae var.parasitica in a sand culture system. All plants were fed with a nutrient solution containing one of two phosphorus (P) levels, 32µM (I P) or 96µM (II P), to test the consequence of enhanced P nutrition by the AM fungus on disease dynamics. Mycorrhizal plants had a similar development to that of control plants. Treatment withPhytophthora nicotianae var.parasitica resulted in a visible reduction in plant weight and in a widespread root necrosis in plants without mycorrhiza. The presence of the AM fungus decreased both weight reduction and root necrosis. The percentage reduction of adventitious root necrosis and of necrotic root apices ranged between 63 and 89% The enhancement of P nutrition increased plant development, but did not appreciably decrease disease spread. In our system, mycorrhiza increased plant resistance toP. nicotianae var.parasitica infection. Although a contribution of P nutrition by mycorrhiza cannot be excluded, other mechanisms appear to play a crucial role.     

Media formulation influences in vitro ectomycorrhizal synthesis on the European aspen Populus tremula L.

The effect of various media formulations on in vitro ectomycorrhizal synthesis of identified fungal strains with European aspen (Populus tremula L.) was tested in Petri dishes. Pre-grown seedlings were transferred to various nutrient media and inoculated with Paxillus involutus isolates using modified sandwich techniques. Mycorrhiza formation was evaluated macroscopically and further confirmed by microscopic examination of semi-thin sections for anatomical features of the mantle and the Hartig net. Standard media formulations did not support successful ectomycorrhiza formation because of either very poor plant survival (below 20%) or impaired fungal growth. The inclusion of micronutrients and vitamins in a Melin Norkrans (MMN)-based medium increased plant survival rate to above 60% and supported successful mycorrhizal synthesis. P. involutus isolates formed mycorrhizas with a characteristic Hartig net restricted to the epidermis. Mantle density and thickness varied depending on the isolate. In a follow-up experiment, the adapted medium supported successful ectomycorrhiza formation by various Laccaria and Hebeloma isolates. Our results show that an exogenous supply of vitamins and micronutrients in the medium was a prerequisite for successful mycorrhization of P. tremula in vitro in Petri dishes.     

Comparative studies of ectomycorrhiza formation in Alnus glutinosa and Pinus resinosa with Paxillus involutus

 Mycorrhiza ontogeny and details of Hartig net and mantle structure were compared in ectomycorrhizas synthesized in growth pouches between the broad host range fungus Paxillus involutus and the tree species European black alder (Alnus glutinosa) and red pine (Pinus resinosa). In Alnus glutinosa, a paraepidermal Hartig net was restricted to the proximal (basal) portion of first-order laterals; the hypodermal layer appeared to be a barrier to fungal penetration. Phi-thickenings were present in some cortical cells but these were not related to lack of fungal ingress into the cortex. The mantle was often present close to the root apex but in many roots it was loosely organized and patchy. In several instances, the mantle formed around the root apex was only temporary; renewed root growth occurred without the formation of a mantle. In Pinus resinosa, the Hartig net developed between cortical cell layers of monopodial and dichotomously branched first–order laterals. Fungal hyphae in the Hartig net exhibited a complex labyrinthine mode of growth. The mantle had a pseudoparenchymatous structure and covered the root, including apices of dichotomously branched roots. The Paxillus–Pinus resinosa interaction had all the characteristics of a compatible ectomycorrhizal association. The Paxillus–Alnus glutinosa interaction, however, showed only aspects of superficial ectomycorrhizas, including the presence of a minimal (sometimes absent) and mostly proximal Hartig net and variable mantle development. Sclerotia were produced in the extraradical mycelium of Paxillus involutus when associated with either Alnus glutinosa or Pinus resinosa. Accepted: 22 October 1998     

Structural features of mycorrhizal associations in two members of the Monotropoideae, Monotropa uniflora and Pterospora andromedea

Species in the subfamily Monotropoideae (family Ericaceae) are achlorophyllous and myco-heterotrophic. They have become highly specialized in that each plant species is associated with a limited number of fungal species which in turn are linked to autotrophic plants. This study provides an updated and comprehensive examination of the anatomical features of two species that have recently received attention with respect to their host-fungal specificity. Root systems of Monotropa uniflora and Pterospora andromedea collected from the field were characterized by light microscopy and scanning electron microscopy. All roots of both species were associated with fungi, each root having a well-developed mantle, paraepidermal Hartig net, and intracellular fungal pegs within epidermal cells. The mantle of M. uniflora was multi-layered and numerous outer mantle hyphae developed into cystidia of two distinct morphologies. Large calcium oxalate crystals were present, primarily on the mantle surface. The outer mantle of P. andromedea was more loosely organized, lacked cystidia, and had smaller plate-like as well as cylindrical crystals on the surface and between outer mantle hyphae. Fungal pegs in M. uniflora originated from inner mantle hyphae that penetrated the outer tangential wall of epidermal cells; in P. andromedea, these structures were initiated either from inner mantle hyphae or Hartig net hyphae and penetrated radial walls of epidermal cells. With respect to function, fungal pegs occurred frequently in both host species and, although presumed to be the sites of active nutrient exchange, no direct evidence exists to support this. Differences between these two monotropoid hosts, resulting from the mycorrhizal fungi with which each associates, are discussed.     

Comparative studies on ectomycorrhizae synthesized with various in vitro techniques using Picea abies and two Hebeloma species

Summary Various in vitro synthesis techniques with Picea abies and two Hebeloma species showed that structures of the mantle and Hartig net of synthesized ectomycorrhizae within the given two fungus species are stable. However, thickness of mantle, and penetration depth and number of hyphal cell rows between cortical cells of the Hartig net are dependent on techniques and substrates. Porous glass balls as substrate in the Erlenmeyer technique seem to suppress or delay mantle and Hartig net formation. With the other techniques (growth pouch, open cuvette, Erlenmeyer with a vermiculite-peat moss mixture) development of the mantle is simultaneous with or shortly in advance of Hartig net formation. The ectomycorrhizae of the two tested Hebeloma species are similar and cannot be morphologically differentiated by the in vitro techniques used.     

中国兰科线柱兰属一新记录种——黄花线柱兰

报道了中国兰科植物一新记录种,黄花线柱兰Zeuxine flava (Wall. ex Lindl.) Benth. ex Hook. f.。本种的唇瓣橘黄色并呈“T”形,前唇裂片成方形,长宽近相等,唇瓣基部囊内各具一枚钩状胼胝体。     

Root hydraulic properties and growth of balsam poplar (Populus balsamifera) mycorrhizal with Hebeloma crustuliniforme and Wilcoxina mikolae var. mikolae

The effects of an E-strain fungus (Wilcoxina mikolae var. mikolae) and an ectomycorrhizal fungus (Hebeloma crustuliniforme) on growth and water relations of balsam poplar were examined and compared in the present study. Balsam poplar roots inoculated with W. mikolae var. mikolae (Wm) exhibited structures consistent with ectendomycorrhizal (EEM) associations, including a mantle surrounding the outside of the root and an extensive Hartig net that was located between cortical cells and extended to the vascular cylinder. Roots colonized with H. crustuliniforme (Hc) developed a mantle layer, indicative of an ectomycorrhizal (ECM) association, around the outer part of the root, but no distinct Hartig net was present. Wm-colonized balsam poplar also showed increased shoot growth, stomatal conductance (g _s), and root volumes compared with non-inoculated and Hc-inoculated plants. However, Hc-inoculated plants had higher root hydraulic conductivity (L _pr) compared with non-inoculated plants and Wm-inoculated plants. These results suggest that L _pr was not a growth-limiting factor in balsam poplar and that hyphal penetration of the root cortex in itself may have little influence on root hydraulic properties.     

Structure and histochemistry of mycorrhizae synthesized between Arbutus menziesii (Ericaceae) and two basidiomycetes,Pisolithus tinctorius (Pisolithaceae) and Piloderma bicolor (Corticiaceae)

Arbutoid mycorrhizae were synthesized in growth pouches between Arbutus menziesii Pursch. (Pacific madrone) and two broad host range basidiomycete fungi, Pisolithus tinctorius (Pers.) Coker and Couch and Piloderma bicolor (Peck) Jülich. P. tinctorius induced the formation of dense, pinnate mycorrhizal root clusters enveloped by a thick fungal mantle. P. bicolor mycorrhizae were usually unbranched, and had a thin or non-existent mantle. Both associations had the well-developed para-epidermal Hartig nets and intracellular penetration of host epidermal cells by hyphae typical of arbutoid interactions. A. menziesii roots developed a suberized exodermis which acted as a barrier to cortical cell penetration by the fungi. Ultrastructurally, the suberin appeared non-lamellar, but this may have been due to the imbedding resin. Histochemical analyses indicated that phenolic substances present in epidermal cells may be an important factor in mycorrhiza establishment. Analyses with X-ray energy dispersive spectroscopy showed that some of the granular inclusions present in fungal hyphae of the mantle and Hartig net were polyphosphate. Other inclusions were either protein or polysaccharides.     

Comparative structural study ofQuercus serrata andQ. acutissima formed byPisolithus tinctorius andHebeloma cylindrosporum

Ectomycorrhizas were synthesized in pots and growth pouches betweenQuercus serrata, Q. acutissima, and two ectomycorrhizal fungi,Pisolithus tinctorius andHebeloma cylindrosporum. Root morphology and the structure of the mantle and Hartig net were compared using light, fluorescence, scanning and transmission electron microscopy.P. tinctorius initially colonized root cap cells, and eventually produced a highly branched lateral root system with a complete mantle, whereasH. cylindrosporum promoted root elongation with few hyphae on the root apex surface indicating that interaction between roots differs with fungal species. Hartig net structure and hyphal inclusions varied between all the combinations tested. There were structural differences between mycorrhizas ofH. cylindrosporum/Q. acutissima grown in soil and growth pouches, which indicate that the growth pouch environment can induce artefacts in roots. Fruit bodies ofH. cylindrosporum developed in pots withQ. acutissima. AlthoughP. tinctorius has been used to inoculate oak seedlings in the nursery, results of this study indicate thatH. cylindrosporum may also be an effective ectomycorrhizal fungus forQ. serrata andQ. acutissima.     

呼伦贝尔沙地樟子松林净初级生产力对气候变化的响应

以呼伦贝尔沙地樟子松人工林为研究对象,利用树木年轮学和解析木法,推算过去41年樟子松林的生物量和年净初级生产力,并分析年净初级生产力与气温、降水、湿度等气象因子的关系。研究表明：随着林龄的增加,樟子松林生物量变化符合逻辑斯蒂生长方程;樟子松林生物量从1977年的4.83 t/hm²到2017年的167.95 t/hm²。樟子松林净初级生产力年际差异较大,呈先增加后减小、最后趋于稳定的趋势,多年平均净初级生产力为4.08 t hm^-2 a^-1,最高达到6.13 t hm^-2 a^-1,最低为2.63 t hm^-2 a^-1。气候因子与樟子松林净初级生产力关系较为密切,并具有一定的"滞后效应";樟子松林净初级生产力与上一年8月、12月和当年3月的降水量显著相关;净初级生产力与上一年和当年8-9月的月均湿度极显著正相关;净初级生产力与各月温度均呈不同程度的负相关,尤其是上一年和当年的6-9月温度显著影响着净初级生产力。研究表明,樟子松林净初级生产力受温度和降水的综合影响,净初级生产力与气候因子的关系属于温度敏感型,未来该地区持续升温的条件下樟子松林净初级生产力可能会降低。     

Stemflow: A Source of Nutrients in some Naturally Growing Epiphytic Orchids of the Sikkim Himalaya

A study on five naturally growing epiphytic orchids viz., Bulbophyllum affine Lindl., Coelogyne ochracea Lindl., Otochilus porrecta Lindl., Cirrhopetalum cornutum Lindl. and C. cornutum (var.) was carried out in the subtropical belt of Sikkim Himalaya. Stemflow leachates formed the main source of ammonium-N and nitrate-N for uptake by these orchids. Phosphorus concentration in the tissues of these orchids was high. Phosphate-P from stemflow does not seem to be a regular source of phosphorus for these orchids. Absorption/desorption results indicate that organic-N from stemflow leachates is not utilized by these orchids.     

Structural aspects of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] tuberculate ectomycorrhizae

Summary Tubercles of Pseudotsuga menziesii consisted of clusters of ectomycorrhizae surrounded by a peridiumlike rind. Energy dispersive spectroscopy demonstrated that crystals found in the zone of loose hyphae extending from the inner rind to the mantle of each root probably contain calcium oxalate. Inner mantle and Hartig net hyphae showed a labyrinthine branching pattern and stored carbohydrates and protein. The Hartig net formed up to inner cortical cells which had thickened, darkly stained walls. Bacteria were located either along with hyphae within the rind or as colonies on the surface of the tubercle.     

Microcallus formation from leaf mesophyll protoplasts in the genus Actinidia Lindl

Summary Microcallus (more than 60 cells) formation was obtained from leaf mesophyll protoplasts of 6 species and varieties in the genus Actinidia Lindl. (kiwifruit). The best results were achieved by using liquid over agarose culture for A. arguta var. arguta, liquid and agarose disc type culture for A. arguta var. purpurea, agarose disc type culture for A. arguta cv. Issaï and A. deliciosa and liquid agarose bead type- and disc type culture for A. kolomikta and A. polygama. Several factors influencing purification, browning, survival and sustained division of the protoplasts are briefly discussed.Abbreviations BAP benzylaminopurine - CPW cell and protoplast washing solution - 2,4-D dichlorophenoxyacetic acid - GA3 gibberellic acid - IAA indole-3-acetic acid - MES 2-(N-morpholino) ethanesulfonic acid - NAA 1-naphthaleneacetic acid - PVP polyvinylpyrrolidone - BT agarose bead type culture - DT agarose disc type culture     

西畴重楼生物学特征补述及其系统位置

西畴重楼(Paris cronquistii var.xichouensis)为云南省特有物种,野外调查发现了广西(田林、那坡)的省级新分布,针对该新分布居群,观测并描述西畴重楼植物形态学特征,记录物候学特征,野外观测其地理分布特征,综上对其生物学特性进行补述,并结合前人基于细胞核ITS、叶绿体psbA-trnH和trnL-trnF等序列的分子系统学研究结果探讨其系统关系。结果表明:西畴重楼叶背面无紫色斑块,花瓣较宽而显著区别于凌云重楼(P.cromquistii var.cromquistii),但西畴重楼部分植株沿叶脉有紫色斑纹,表明与凌云重楼存在形态过渡,二者雄蕊数量均以3轮为主,而且变化范围一致;西畴重楼的物候期与同域分布的凌云重楼相近,同南重楼(P.vietnamensis)差异显著;西畴重楼多条序列的分子系统学研究显示西畴重楼和凌云重楼始终聚为一支,证实二者高度的亲缘关系。该研究结果完善了西畴重楼的生物学特性描述,首次报道了西畴重楼与凌云重楼形态特征存在过渡类型,物候学特征较一致,地理分布中心重叠,分子系统学位置相邻,仍支持李恒系统将西畴重楼作为凌云重楼的一变种。     

Taxonomic position of a Chinese <Emphasis Type="Italic">Pleurotus</Emphasis> “Bai-Ling-Gu”: it belongs to <Emphasis Type="Italic">Pleurotus eryngii</Emphasis> (DC.: Fr.) Quél. and evolved independently in China

The Chinese Bai-Ling-Gu is a mushroom named Pleurotus eryngii var. tuoliensis C.J. Mou. This species has been identified as P. nebrodensis or P. eryngii var. nebrodensis. We examined its taxonomic position by analysis of mating, cultivation, and rDNA sequences, and concluded as follows. (1) Bai-Ling-Gu mated with P. eryngii var. eryngii, and the F₁ and F₂ formed fruit bodies. (2) Bai-Ling-Gu mated with P. eryngii var. ferulae, and the F₁ formed fruit bodies. (3) In the di-mon mating test, P. eryngii var. nebrodensis from Sicily mated with monokaryons of P. eryngii var. eryngii but mated hardly at all with those of Bai-Ling-Gu and P. eryngii var. ferulae. The di-mon mating pattern of Bai-Ling-Gu resembled those of P. eryngii var. ferulae. (4) The partial sequences of rDNA ITS1 and IGS1 from the epitype of P. nebrodensis were identical with those from P. eryngii var. nebrodensis from Sicily but differed from those from Bai-Ling-Gu. (5) The strains of P. eryngii var. eryngii and P. eryngii var. ferulae were in a group, the strains of P. eryngii var. nebrodensis from Sicily were in another group, and the strains of Bai-Ling-Gu were in the other group in both the phylogenetic trees based on the ITS1 and the IGS1 sequences. These results led to the conclusion that Bai-Ling-Gu is a variety of P. eryngii and evolved independently in China. It is satisfactory to identify Bai-Ling-Gu with P. eryngii var. tuoliensis C.J. Mou.     

Chemical and sensory analysis of saffron produced through tissue cultures of Crocus sativus

Stigma-like structures were produced in tissue cultures (TC stigmas) from the ovary explants of C. sativus on MS medium supplemented with NAA and BA. The size of these structures was 2 to 3 cm in length. At higher concentrations of both NAA (54 µM) and BA (44 µM) white tubular abnormal structures were observed from ovary explants in addition to the TC stigmas. Crocin and picrocrocin, responsible for colour and bitter taste respectively, were found to be 6 and 11 times lower in TC stigmas than in the natural stigmas. The saffron obtained from tissue cultures was subjected to sensory analysis and compared with the data obtained from chemical analysis. The sensory data indicated that the saffron pigments produced in tissue cultures were one tenth that of natural stigmas. Sensory profile test showed that the tissue culture saffron was low in floral, spicy and fatty characteristics as compared to saffron obtained from flowers. This is the first report on the sensory analysis of a spice produced in tissue cultures.Abbreviations BA benzyladenine - NAA naphthaleneacetic acid     

Evaluation of morphological and molecular variation in Plantago asiatica var. densiuscula, with special reference to the systematic treatment of Plantago asiatica var. yakusimensis

Morphological and molecular variations in Plantago asiatica L. var. densiuscula Pilg. were analyzed to evaluate the genetic basis for recognizing the dwarf variety P. asiatica var. yakusimensis (Masam.) Ohwi. Considerable variation in the leaf size of P. asiatica var. densiuscula was observed, and no morphological discontinuities were found between the dwarf types of P. asiatica var. densiuscula and P. asiatica var. yakusimensis. Morphological analysis of plants grown under standardized conditions revealed that both environmental plasticity and genetic differentiation contributed to the dwarfisms. Molecular phylogenetic analysis of rDNA internal transcribed spacer (ITS) regions and the SUC1 locus encoding a sucrose transporter revealed that P. asiatica var. yakusimensis was genetically unique although the differentiation level was low. From the above results, we concluded that P. asiatica var. yakusimensis should be reduced to a form of P. asiatica var. densiuscula. Furthermore, the geographic distribution of the SUC1 genotype suggested multiple origins of dwarves, and possible hypotheses for the origins of dwarves are discussed.     

Some distinctive types of spruce mycorrhizae

Summary For examination and recognition of mycorrhizal types, the structure of the hyphal mantle in tangential longitudinal sections has proved to be a valuable feature for investigation. Features of hyphal mantle structure have been used for establishing an identification key. The colour of the hyphal mantle is a helpful additional characteristic, but is not useful as a diagnostic feature because of variations in advanced age and under varying environmental conditions. Rhizomorphs yield good taxonomic characteristics. The Hartig net was uniform for all types examined. When differences were observed they had to be interpreted as different stages of development. Ultrastructural examination revealed further features of mycorrhizal types: namely the shape of septal pores, presence and structure of matrix material in the region of the hyphal mantle and characteristic deposits on cell walls of the hyphae. The ten types presented can be distinguished without any ultrastructural features. As far as the fungal partners involved are concerned, basidiomycetes are clearly dominant. For the first time two basidiomycetes with continuous parenthesomes of their dolipores were found to form ectomycorrhizae. Classification of these fungi with the heterobasidiomycetes is discussed.     

917. CORETHROGYNE FILAGINIFOLIA

Corethrogyne filaginifolia (Hook. & Arn.) Nutt. (Compositae: Astereae: Machaerantherinae) is illustrated and described. The full synonymy of this monospecific North American genus is provided together with the location of known type material and relevant comments made where applicable. The Conservation Status of the species is considered LC (Least Concern), as previous listings in California are shown to refer to Corethrogyne filaginifolia (Hook. & Arn.) var. incana (Lindl.) D.R. Morgan & R.L. Hartman, which is now considered a synonym of the rather variable Dieteria canescens (Pursh) Nutt. The taxonomic placement of Diplopappus incanus Lindl. is discussed, and a synonymy has been provided for Dieteria canescens subsp. canescens var. incana (Lindl.) D.R. Morgan & R.L. Hartman, of which it is the basionym. The location of the probable holotype of Diplopappus leucophyllus Lindl. ex DC. is discussed, together with the relevance of material mounted on a Kew sheet.     

Saffron reduces ATP-induced retinal cytotoxicity by targeting P2X7 receptors

P2X7-type purinergic receptors are distributed throughout the nervous system where they contribute to physiological and pathological functions. In the retina, this receptor is found in both inner and outer cells including microglia modulating signaling and health of retinal cells. It is involved in retinal neurodegenerative disorders such as retinitis pigmentosa and age-related macular degeneration (AMD). Experimental studies demonstrated that saffron protects photoreceptors from light-induced damage preserving both retinal morphology and visual function and improves retinal flicker sensitivity in AMD patients. To evaluate a possible interaction between saffron and P2X7 receptors (P2X7Rs), different cellular models and experimental approaches were used. We found that saffron positively influences the viability of mouse primary retinal cells and photoreceptor-derived 661W cells exposed to ATP, and reduced the ATP-induced intracellular calcium increase in 661W cells. Similar results were obtained on HEK cells transfected with recombinant rat P2X7R but not on cells transfected with rat P2X2R. Finally, patch-clamp experiments showed that saffron inhibited cationic currents in HEK-P2X7R cells. These results point out a novel mechanism through which saffron may exert its protective role in neurodegeneration and support the idea that P2X7-mediated calcium signaling may be a crucial therapeutic target in the treatment of neurodegenerative diseases.