The diversity of mycorrhizal fungi in Japanese Cephalanthera species

The diversity of mycorrhizal fungi among four Japanese Cephalanthera (Orchidaceae) species was examined at a total of seven sites, based on sequence variation in nuclear ribosomal DNA. This is the first report to detect mycorrhizal fungi in C. subaphylla. Two patterns of mycorrhizal associations were confirmed from our results. C. falcata has lower fungal specificity, associating with Russulaceae, Sebacinales and Thelephoraceae. By contrast, the three Cephalanthera species C. erecta, C. subaphylla, and C. longifolia were associated mainly with Thelephoraceae fungi. There is no large difference found in mycobionts between green and albino individuals of C. falcata and no distinct preference of Japanese Cephalanthera species for a specific fungal group of Thelephoraceae.     

The Effect of Seed Cryopreservation on the Development of Protocorms by the Hybrid Orchid Bratonia

The aim of this work was to study the influence of storage in liquid nitrogen on the viability of seeds of the hybrid orchid Bratonia and further development of its protocorms in vitro. Seeds were frozen in ampoules by direct immersion in liquid nitrogen and stored in the cryobank for a month. The germination rates of cryopreserved and control (nonfrozen) seeds did not differ and remained as high as 100%. The protocorms derived were cultured on the agar-solidified Murashige and Skoog nutrient medium (MS), half-strength MS and Knop media and also in Morel liquid medium. During the first 45 days of culturing, protocorms derived from cryopreserved seeds grew faster than control protocorms on the MS and half-strength MS media but, at longer culturing (496 days), the size of control protocorms was significantly larger. After 639 days of culturing, there was no difference in the amount of perished, budding, and newly formed protocorms obtained from cryopreserved and control seeds, except half-strength MS medium where the number of budding protocorms in the case of cryopreserved seeds was a little greater than in the control treatment. After seed cryopreservation, the frequency of budding and newly formed protocorms was greater on the agarized MS and in liquid Morel media. Cryopreservation had little effect on the subsequent growth of protocorms in vitro. The preferable nutrient media for culturing the protocorms have been suggested.     

Mecardonia tenella (Plantaginaceae) Attracts Oil-, Perfume-, and Pollen-Gathering Bees in Southern Brazil

Floral characteristics often indicate the pollinators' functional group visiting the plant and the pollination syndromes associated with them. This idea has been challenged in the past decades due to increasing evidence that most plants, including those exhibiting floral syndromes, are visited by large arrays of species that differ in their effectiveness as pollinators. Our study focuses on Mecardonia tenella (Plantaginaceae) from the Araucaria forest of southern Brazil, which exhibits characteristics of the oil flower pollination syndrome. However, it is visited by three types of functional groups of bees: male orchid bees, oil-collecting bees, and pollen-seeking bees. The relative contribution of each functional group to the plant's reproductive success was estimated based on their pollen load, visitation frequency, and morphology. We assessed resources, phenology, and breeding system of M. tenella . Our results indicate that flowers lack nectar, but volatiles, lipids, and pollen are resources that can be gathered by visitors. This combination of floral traits and visitors' assemblage makes M. tenella a challenge to the concept of pollination syndromes. Our findings indicate that the current interactions may not reflect the circumstances under which some floral traits of this plant were selected.     

Asymbiotic seed germination and in vitro seedling development of <Emphasis Type="Italic">Cyrtopodium punctatum</Emphasis>: a propagation protocol for an endangered Florida native orchid

Cyrtopodium punctatum Lindley is an endangered epiphytic orchid restricted in the United States to southern Florida. Due to its ornamental value, the species was extensively collected from the wild during the past 100 years. Today, only a few plants remain in protected areas. As part of a conservation plan for the species, procedures for asymbiotic seed germination were developed. Five asymbiotic orchid seed germination media (PhytoTechnology Orchid Seed Sowing Medium, Knudson C, Malmgren Modified Terrestrial Orchid Medium, Vacin &; Went Modified Orchid Medium, and ½-strengh Murashige &; Skoog) were examined for their effectiveness in promoting seed germination and protocorm development under a 16/8 h L/D photoperiod and dark (0/24 h L/D). The influence of photoperiod on growth and development was also examined. Seeds were germinated under a 16/8 h, 12/12 h, 8/16 h L/D photoperiod, at 25 ± 3°C and allowed to develop in vitro for 10 weeks. After 10 weeks, developing seedlings were transferred to Sigma Phytatrays and returned to their assigned photoperiod treatments for continued seedling development for an additional 15 weeks. Highest germination occurred in 0/24 h L/D on PhytoTechnology Orchid Seed Sowing Medium and seedlings displayed more advanced development when cultured under 16/8 h L/D photoperiod after 15 weeks in Phytatrays. Thirty-five week old seedlings potted in coconut husk growing medium exhibited 90% survival following 5 weeks acclimatization to greenhouse conditions. This asymbiotic seed germination protocol for C. punctatum will facilitate future reintroduction projects involving this endangered species.     

Growth and viability of mycorrhizal extraradical mycelia associated with three temperate orchid species

Growth and enzymatic activities of extraradical mycelia (ERM) of native mycorrhizal symbionts associated with three orchid species, Dactylorhiza fuchsii, D. majalis and Platanthera bifolia, were studied. ERM extracted from the mycorrhizosphere of these species showed features typical for fungi that form orchid mycorrhiza. In the first pot experiment, three different treatments were applied on tubers of D. fuchsii transplanted from a natural site: control (no specific treatment), reinoculated (surface-sterilized tubers reinoculated with mycorrhizal fungi-colonised roots), and benomyl (nonsterilized tubers treated with fungicide). However, no significant differences in ERM growth and intensity of root mycorrhizal colonisation at harvest were observed among these treatments. ERM associated with reinoculated D. fuchsii plants showed significantly higher alkaline phosphatase (ALP) enzymatic activity at week 36 than at week 24, but no differences were observed for NADH diaphorase activity. Benomyl application significantly reduced ALP activity in comparison with reinoculated plants at week 36. In the second experiment, plants of all three species were either untreated (control), or repeatedly treated with benomyl. Similarly to the results of the first experiment, benomyl application did not reduce the ERM growth of mycorrhizal symbionts associated with D. majalis and D. fuchsii. The low ERM growth associated with benomyl-treated P. bifolia was probably caused by poor root system development in this treatment. Significantly higher mycorrhizal colonisation was found for D. fuchsii compared to P. bifolia in control treatments at the end of cultivation. The ERM of native symbionts of the three orchid species studied seemed to have a different growth pattern over time and responded differently to fungicide application.     

Interaction between a dark septate endophytic isolate from Dendrobium sp. and roots of D. nobile seedlings

Interactions between an isolate of dark septate endophytas (DSE) and roots of Dendroblum nobile Lindl.seedlings are reported in this paper.The isolate was obtained from orchid mycorrhizas on Dendrobium sp.in subtropical forest.The fungus formed typical orchid mycorrhiza in aseptic co-culture with D.nobile seedlings on modified Murashige-Skoog (MMS)medium.Anatomic observations of the infected roots showed that the DSE hyphae invaded the velamen layer,passed through passage cells in exodermis,entered the cortex cells,and then formed fungal pelotons of orchid mycorrhiza.D.nobile seedlings' plant height,stem diameter,new roots number and biomass were greatly enhanced by inoculating the fungus to seedlings.The fungus was identified as Leptodontidium by sequencing the polymerase chain reaction-amplified rDNA ITSt-5.8S-ITS2 (internal transcribed spacer (ITS)) regions and comparison with similar taxa.     

弯曲姿态蛾类幼虫的自动识别方法研究

【目的】为害态幼虫现场识别时, 幼虫常出现姿态弯曲情况, 使提取的特征向量失真, 影响幼虫的匹配识别结果。本文提出了一种基于扇形变换的姿态不变胡氏矩特征向量提取方法, 提取的病害幼虫特征向量具有平移、 比例、 旋转和姿态不变性, 可以实现粗短弯曲姿态幼虫的自动识别。【方法】首先在幼虫图像细化的基础上采用最优一致逼近法确定了幼虫的弯曲区域和非弯曲区域。然后, 幼虫的弯曲区域采用扇形变换实现校正变直, 非弯曲区域经旋转和平移与扇形变换后的区域拼接组成完整虫体; 采用八邻域均值法填充变换后虫体区域中的空白点, 实现幼虫像的弯曲自动校正; 在此基础上提取胡氏不变矩具有姿态不变性, 采用最小距离分类器实现了多姿态幼虫的自动识别。最后, 以多种弯曲姿态的斜纹夜蛾Prodenia litura、 棉铃虫Heliocoverpa armigera、 甜菜夜蛾Spodoptera exigua、 玉米螟Ostrinia nubilalis等病害蛾类幼虫为识别对象进行了识别验证。【结果】对于24种不同姿态的幼虫图像, 在80%的识别阈值条件下, 基于经典胡氏不变矩的幼虫识别率为25%, 基于姿态不变胡氏矩的识别率为100%。【结论】实验结果表明该方法对多种弯曲姿态的粗短幼虫具有较高的识别率。     

基于标本和分布信息评估中国虾脊兰属 植物的濒危状况

兰科植物是生物多样性保护的旗舰类群之一, 但如何客观准确地评估兰科植物的濒危状况, 一直是生物多样性保护中急需解决的问题。本文以中国虾脊兰属(Calanthe)植物为例, 探讨了基于馆藏标本和野外分布信息进行兰科植物红色名录濒危等级评估的利弊。我们的研究表明, 馆藏标本能够比较客观地反映物种地理分布信息和相应的野外居群状况, 但对于物种分布的历史变化和受威胁因素反映不足; 而野外工作对于物种的实际分布状况和受威胁因素等的反映比较客观, 但能发现的物种和居群数量有限, 部分极小种群物种在短时间野外工作中很难发现。我们的研究认为, 有2种虾脊兰属植物应被评估为野外灭绝(EW), 16种应被评估为极度濒危(CR)。可见, 中国虾脊兰属植物濒危的状况远比前人的评估结果要严重得多。     

Effects of distance from models on the fitness of floral mimics

• Rewardless plants can attract pollinators by mimicking floral traits of rewarding heterospecific plants. This should result in the pollination success of floral mimics being dependent on the relative abundance of their models, as pollinator abundance and conditioning on model signals should be higher in the vicinity of the models. However, the attraction of pollinators to signals of the models may be partially innate, such that spatial isolation of mimics from model species may not strongly affect pollination success of mimics.
• We tested whether pollination rates and fruit set of the rewardless orchid Disa pulchra were influenced by proximity and abundance of its rewarding model species, Watsonia lepida.
• Pollination success of the orchid increased with proximity to the model species, while fruit set of the orchid increased with local abundance of the model species. Orchids that were experimentally translocated outside the model population experienced reduced pollinaria removal and increased pollinator‐mediated self‐pollination.
• These results confirm predictions that the pollination success of floral mimics should be dependent on the proximity and abundance of model taxa, and thus highlight the importance of ecological facilitation among species involved in mimicry systems.