Phylogenetic position of Apostasia and Neuwiedia (Orchidaceae)

JUDD, W. S., STERN, W. L. & CHEADLE, V. I. 1993. Phylogenetic position of Apostasia and Neuwiedia (Orchidaceae). Cladistic analyses of the phylogenetic relationships of selected orchid taxa were conducted in order to assess the phylogenetic position of Apostasia and Neuwiedia (Orchidaceae: Apostasioideae). These analyses employed newly available anatomical characters, along with several morphological features that had been used in recent phylogenetic analyses of Orchidaceae. Our analyses indicate that Apostasia is more closely related to Neuwiedia than it is to Cypripedioideae. The two genera comprise an apostasiad clade; this clade is the sister-group to a clade including Cypripedioideae and monandrous orchids. The apostasiad clade is diagnosed by the derived features of operculate pollen colpi, Apostasia-type seeds, and vessel members with simple perforation plates. Of these, the presence of simple perforation plates is considered to be the most significant phylogenetically. Therefore, the apostasiads should not be considered ancestral to the remaining orchid groups. Vessel members of the monandrous orchids, as well as the cypripediads, are multiperforate–the hypothesized ancestral state based on the condition in Hypoxidaceae.     

Molecular identification of mycorrhizal fungi in Neuwiedia veratrifolia (Orchidaceae)

We here apply a previously described method for identification of single peloton orchid mycorrhiza to a key orchid group and extend the usefulness in the heterobasidiomycetes of an existing fungal database for identification of mycorrhizal fungi. We amplified and sequenced mitochondrial ribosomal large subunit DNA from fungi in roots of Neuwiedia veratrifolia (Orchidaceae), a member of the small subfamily Apostasioideae that is sister to the remainder of Orchidaceae, and used the extended database to identify the mycorrhizal fungi. Sequences from fungi cultured from Neuwiedia roots and from direct peloton amplifications were analyzed cladistically with sequences determined from reference fungal collections and published sequences. The fungi from Neuwiedia are referred to the heterobasidiomycetous orders Tulasnellales and Ceratobasidiales, indicating that apostasioids utilize the same fungi as other photosynthetic orchids. The majority of Neuwiedia mycobionts came together in a clade with Tulasnella species, but some were most closely related to Thanatephorus. In some cases members of these two clades were isolated from the same orchid plant, providing another example of multiple mycobionts occurring in a single plant.     

Apostasiads, systematic anatomy, and the origins of Orchidaceae

Anatomical study of several species of the putatively primitive orchids Apostasia and Neuiviedia was based on specimens of leaves, stems and rootS. Research was carried out in the hope of providing objective information from anatomy towards unravelling the relationships of these plants, and especially towards answering the question of whether extant orchids evolved from these two genera, or from plants like them. The morphology of Apostasia and Neuwiedia has evoked the dogma of primitiveness because of the two or three anthers borne on separate filaments and the free style and stigma which characterize the flowerS. In most other orchids there is only one anther and filaments and styles are fused to form the column (gynostemium). The general anatomical structure of apostasiads shows features present in other orchids; none is restricted to Apostasia and Neuwiedia. Tracheary anatomy, however, shows vessels in roots, but not in any part of the shoot system. Vessel members are characterized by chiefly simple perforation plates in contrast with other orchids where scalariform perforation plates predominate in vessel members of the root. These phenomena, considered from the phylogenetic standpoint, would cast serious doubt on the possibility that plants with scalariform perforation plates, the ancestral, or primitive condition, could have arisen from plants with simple perforation plates, the derived, or advanced condition. On this basis the apostasiads could not have given rise to the di- and monandrous orchidS. Of the several suggested origins for orchids, Hypoxidaceae, or plants similar to them, whether in Asparagales, Liliales or Haemadorales of different authors, could have been the progenitors of orchids as a group, including the apostasiadS. Because of the unique combination of floral features in the apostasiads, their predominantly simple perforation plates, and their overall anatomical similarity to orchids in general, it would appear appropriate to consider them as a subfamily, Apostasioideae, of Orchidaceae sensu lato.     

兰科植物内生细菌物种多样性及其促生机理研究进展

内生细菌影响兰科植物菌根形成和共生关系的稳定性,在兰科植物的生活史中起着重要作用。内生细菌通过分泌植物激素、采用光合作用、生物固氮或促进矿质营养的循环以及产生铁载体、合成其他活性物质等途径来促进兰科植物生长发育。综述了兰科植物内生细菌物种多样性的研究方法及其对兰科植物的促生机理,基于兰科植物与共生微生物的密切关系,认为内生细菌间、内生细菌与兰科植物菌根真菌间的互作是揭示兰科植物与内生细菌互作机理的重要方向。     

Impact of floral traits on the reproductive success of epiphytic and terrestrial tropical orchids

We investigated the relationship between habit, population size, floral traits and natural fruit set levels of 23 tropical orchid species of south-east Bangladesh. We showed that epiphytic orchids had lower fruit set levels than terrestrial species and that habit explained much of the variation in floral traits among the orchids. We compared our results with data from 76 other species occurring in the study area and hypothesize that a suite of floral and population characteristics present in tropical orchids combine in epiphytes to reduce their reproductive success. Characteristics which, in addition to their habit, are associated with low reproductive success are small population size, small inflorescences, non-sectile pollinia and self-incompatibility. Several of these characteristics were phylogenetically conserved and we predict that epiphytes might therefore generally have lower fruit set levels than recorded in terrestrial species. Nectar rewards are uncommon in tropical orchids and nectarless species have displays of larger flowers, which may represent an adaptation to increase pollinator attraction, although other rewards such as oils, waxes and pseudo pollen may replace nectar. We suggest that, like many temperate orchids, a high proportion of tropical orchids may lack floral rewards and be pollinated by deceit.     

Floral anatomy and systematics of Alliaceae with particular reference to Gilliesia, a presumed insect mimic with strongly zygomorphic flowers

The floral structure of Alliaceae is assessed in relation to the systematics of the family, especially the nature of the component parts of the remarkably insect-like flower of Gilliesia graminea. Both presence of solid styles and possession of tenuinucellate ovules represent consistent synapomorphies for Alliaceae and support the separation of Agapanthus and Themidaceae from Alliaceae. Within Alliaceae, absence of septal nectaries (i.e., complete fusion of carpel margins) is a synapomorphy for the sister genera Gilliesia and Gethyum; septal nectaries are present in all other Alliaceae. A gynobasic style and reduced ovule number are probable synapomorphies for the genus Allium. In contrast to most other Alliaceae, in Gethyum and Gilliesia only three (abaxial) stamens (A1, a1, a2) are expressed, as in the apostasioid orchid Neuwiedia, but the perianth of Gethyum is only slightly bilaterally symmetric (zygomorphic), whereas Gilliesia graminea shows bilateral symmetry in all three floral whorls: perianth (suppression of the inner adaxial tepal in most flowers), androecium (suppression of three adaxial stamens), and gynoecium (slight bilateral symmetry, evident in transverse section). The precise relationships of Miersia and Solaria, the other two genera of Alliaceae with bilaterally symmetric flowers, are unknown, but their morphology indicates a close relationship with Gilliesia and Gethyum. Appendages of tepaline origin occur in Gethyum, Gilliesia, and Miersia; their papillate epidermis suggests that they function as osmophores. Their presence in Miersia, which has six stamens, indicates that these novel structures, which develop late in floral ontogeny, evolved independently from stamen suppression in this group. Within Gilliesia graminea, the genetic mechanisms controlling tepal number and shape are apparently unstable, resulting in fluctuating asymmetry. In G. graminea the possession of insect mimicry, presence of osmophores and absence of nectar together indicate a deceitful pollination mechanism similar to that of some Orchidaceae; this would make Gilliesia highly unusual among non-orchid monocots, given that pollination by sexual deceit is normally regarded as exclusive to orchids.     

Evidence for pollinator sharing in Mediterranean nectar-mimic orchids: absence of premating barriers?

Pollinator specificity has traditionally been considered the main reproductive isolation mechanism in orchids. Among Mediterranean orchids, however, many species attract and deceive pollinators by mimicking nectar-rewarding plants. To test the extent to which deceptive orchid species share pollinators, we collected and identified hemipollinaria-carrying insects, and used ribosomal sequences to identify the orchid species from which hemipollinaria were removed. We found that social and solitary bees, and also flies, carried hemipollinaria belonging to nine orchid species with different degrees of specialization. In particular, Anacamptis morio, Dactylorhiza romana and Orchis mascula used a large set of pollinator species, whereas others such as Orchis quadripunctata seemed to be pollinated by one pollinator species only. Out of the insects with hemipollinaria, 19% were found to carry hemipollinaria from more than one orchid species, indicating that sympatric food-deceptive orchids can share pollinators. This sharing was apparent even among orchid sister-species, thus revealing an effective overlap in pollinator sets among closely related species. These results suggest varying degrees of pollinator specificity in these orchids, and indicate that pollinator specificity cannot always act as the main isolation mechanism in food-deceptive temperate orchids.     

Patterns of reproductive isolation in Mediterranean deceptive orchids

The evolution of reproductive isolation is of central interest in evolutionary biology. In plants, this is typically achieved by a combination of pre- and postpollination mechanisms that prevent, or limit, the amount of interspecific gene flow. Here, we investigated and compared two ecologically defined groups of Mediterranean orchids that differ in pollination biology and pollinator specificity: sexually deceptive orchids versus food-deceptive orchids. We used experimental crosses to assess the strength of postmating prezygotic, and postzygotic reproductive isolation, and a phylogenetic framework to determine their relative rates of evolution. We found quantitative and qualitative differences between the two groups. Food-deceptive orchids have weak premating isolation but strong postmating isolation, whereas the converse situation characterizes sexually deceptive orchids. Only postzygotic reproductive isolation among food-deceptive orchids was found to evolve in a clock-like manner. Comparison of evolutionary rates, within a common interval of genetic distance, showed that the contribution of postmating barriers was more relevant in the food-deceptive species than in the sexually deceptive species. Asymmetry in prezygotic isolation was found among food-deceptive species. Our results indicate that postmating barriers are most important for reproductive isolation in food-deceptive orchids, whereas premating barriers are most important in sexually deceptive orchids. The different rate of evolution of reproductive isolation and the relative strength of pre- and postmating barriers may have implication for speciation processes in the two orchid groups.     

Generalized food-deceptive orchid species flower earlier and occur at lower altitudes than rewarding ones

Aims Food-deceptive pollination, in which plants do not offer any food reward to their pollinators, is common within the Orchidaceae. As food-deceptive orchids are poorer competitors for pollinator visitation than rewarding orchids, their occurrence in a given habitat may be more constrained than that of rewarding orchids. In particular, the success of deceptive orchids strongly relies on several biotic factors such as interactions with co-flowering rewarding species and pollinators, which may vary with altitude and over time. Our study compares generalized food-deceptive (i.e. excluding sexually deceptive) and rewarding orchids to test whether (i) deceptive orchids flower earlier compared to their rewarding counterparts and whether (ii) the relative occurrence of deceptive orchids decreases with increasing altitude.Methods To compare the flowering phenology of rewarding and deceptive orchids, we analysed data compiled from the literature at the species level over the occidental Palaearctic area. Since flowering phenology can be constrained by the latitudinal distribution of the species and by their phylogenetic relationships, we accounted for these factors in our analysis. To compare the altitudinal distribution of rewarding and deceptive orchids, we used field observations made over the entire Swiss territory and over two Swiss mountain ranges.Important findings We found that deceptive orchid species start flowering earlier than rewarding orchids do, which is in accordance with the hypotheses of exploitation of naive pollinators and/or avoidance of competition with rewarding co-occurring species. Also, the relative frequency of deceptive orchids decreases with altitude, suggesting that deception may be less profitable at high compared to low altitude.     

环境因子对海南岛野生兰科植物物种组成与分布格局的影响

海南岛是中国兰科植物物种丰富度较高的地区, 了解环境因子对海南岛野生兰科植物物种组成和分布格局的影响, 对于该地区野生兰科植物的保护管理和相关研究具有重要指导意义。基于海南岛野生兰科植物调查分布样方的植被类型、海拔、坡向、坡度、年平均气温、年降水量的数据, 采用典范相关分析探索了环境因子对物种组成的影响, 并计算各个环境因子对物种组成的总效应与净效应, 同时分析了6个环境因子对野生兰科植物分布格局的影响。结果表明, 所选的6个环境因子共解释了海南岛野生兰科植物组成变异的3.7%; 植被类型、海拔、年平均气温、年降水量、坡向、坡度这6个环境因子的总效应与净效应均达显著水平, 但其解释率依次减小。所选的6个环境因子对海南岛野生兰科植物的分布均有影响, 野生兰科植物在海南岛主要分布在中海拔段、5°-35°的坡度范围、阴坡与半阴坡、年平均气温较低且年降水量较高的环境, 并且于原生植被中分布最多。     

How an orchid harms its pollinator

Certain orchids produce flowers that mimic the sex pheromones and appearance of female insects in order to attract males by sexual deception for the purpose of pollination. In a series of field experiments, we found that the sexually deceptive orchid, Chiloglottis trapeziformis, can have a negative impact on its wasp pollinator Neozeleboria cryptoides. Male and female wasps, however, were affected differently by the orchid's deceit because of their different roles in the mimicry system. Male wasps could not discriminate between the chemical cues of orchids and female wasps, a vital signal in long-range attraction. Males, however, learn to avoid areas containing orchids. This strategy has implications for females attempting to attract mates in areas occupied by orchids. Compared with circumstances when females were on their own, females in the presence of orchids elicited fewer male approaches and no copulation attempts. Females in a large orchid patch also elicited fewer male approaches than females in a small patch. The nature of the orchid's impact on its wasp pollinator indicates an arms race evolutionary scenario in this interaction between plant and pollinator.     

The importance of associations with saprotrophic non-Rhizoctonia fungi among fully mycoheterotrophic orchids is currently under-estimated: novel evidence from sub-tropical Asia

Background and Aims Most fully mycoheterotrophic (MH) orchids investigated to date are mycorrhizal with fungi that simultaneously form ectomycorrhizas with forest trees. Only a few MH orchids are currently known to be mycorrhizal with saprotrophic, mostly wood-decomposing, fungi instead of ectomycorrhizal fungi. This study provides evidence that the importance of associations between MH orchids and saprotrophic non-Rhizoctonia fungi is currently under-estimated.Methods Using microscopic techniques and molecular approaches, mycorrhizal fungi were localized and identified for seven MH orchid species from four genera and two subfamilies, Vanilloideae and Epidendroideae, growing in four humid and warm sub-tropical forests in Taiwan. Carbon and nitrogen stable isotope natural abundances of MH orchids and autotrophic reference plants were used in order to elucidate the nutritional resources utilized by the orchids.Key Results Six out of the seven MH orchid species were mycorrhizal with either wood- or litter-decaying saprotrophic fungi. Only one orchid species was associated with ectomycorrhizal fungi. Stable isotope abundance patterns showed significant distinctions between orchids mycorrhizal with the three groups of fungal hosts.Conclusions Mycoheterotrophic orchids utilizing saprotrophic non-Rhizoctonia fungi as a carbon and nutrient source are clearly more frequent than hitherto assumed. On the basis of this kind of nutrition, orchids can thrive in deeply shaded, light-limiting forest understoreys even without support from ectomycorrhizal fungi. Sub-tropical East Asia appears to be a hotspot for orchids mycorrhizal with saprotrophic non-Rhizoctonia fungi.     

中国1,334种兰科植物就地保护状况评价

作者通过对中国543个自然保护区内兰科植物数据的分析,对我国1,334种兰科植物的就地保护状况进行了逐一评价。我们根据有记录分布保护区的数量,通过专家咨询的方式,将兰科植物就地保护水平划分为"有效保护"、"较好保护"、"一般保护"、"较少保护"、"保护状况不明"和"未予评价"6个等级。结果发现:有676种兰科植物在自然保护区内得到了不同程度的就地保护,占所评价兰科植物总数的51.9%;但有626种兰科植物保护状况不明,尚未受到就地保护,占总数的46.9%。另外有32种仅分布在香港、澳门和台湾地区,本研究中未予评价,约占总数的2.4%。根据评价结果,就兰科植物就地保护中存在的基础调查不足、受关注程度低、受保护率低等问题进行了深入的讨论,提出5条有针对性的建议对策:(1)加强兰科植物的调查监测;(2)提高兰科植物的保护级别与受关注程度;(3)进一步完善兰科自然保护区建设;(4)规范自然保护区综合科学考察;(5)定期评价我国兰科植物保护成效。     

广东象头山国家级自然保护区兰科植物垂直分布格局

于2019～2022年对广东象头山国家级自然保护区内的兰科植物进行专项调查,记录兰科植物种类、数量、生活型、海拔、生境等信息,分析保护区内兰科植物的垂直分布格局,并根据《广东高等植物红色名录》和《国家重点保护野生植物名录》对各海拔高度兰花濒危等级的物种数量进行统计。结果显示：(1)实地记录兰科植物33属48种,多数种类种群数量较少;(2)随着海拔上升,各海拔梯度的兰科植物总种数和不同生活型的种数均呈现“中间高度膨胀型”分布特点,峰值在中低海拔区域;(3)濒危物种主要集中在海拔200～500 m区间;(4)相邻海拔段的兰科植物种类相似性系数较高,垂直梯度差异越大,相似性系数越小。低海拔地区可能由于人为干扰频繁,兰科植物物种多样性较低;中海拔物种多样性最丰富;高海拔地区生长环境较苛刻,物种数量较少。     

Orchid sexual deceit provokes ejaculation

Sexually deceptive orchids lure pollinators by mimicking female insects. Male insects fooled into gripping or copulating with orchids unwittingly transfer the pollinia. The effect of deception on pollinators has been considered negligible, but we show that pollinators may suffer considerable costs. Insects pollinating Australian tongue orchids (Cryptostylis species) frequently ejaculate and waste copious sperm. The costs of sperm wastage could select for pollinator avoidance of orchids, thereby driving and maintaining sexual deception via antagonistic coevolution or an arms race between pollinator learning and escalating orchid mimicry. However, we also show that orchid species provoking such extreme pollinator behavior have the highest pollination success. How can deception persist, given the costs to pollinators? Sexually-deceptive-orchid pollinators are almost exclusively solitary and haplodiploid species. Therefore, female insects deprived of matings by orchid deception could still produce male offspring, which may even enhance orchid pollination.     

四川黄龙沟优势兰科植物菌根真菌多样性及其季节变化

在自然条件下,兰科菌根真菌对兰花的种子萌发和植株生长都是必不可少的。为了解高原兰科植物菌根真菌的多样性状况及其季节性变化规律,选取了四川黄龙沟的两种生境中生长的8种优势兰科植物,分别于植株的萌芽期(4月份)、生长期(7月份)和果期(9月份)采集营养根进行菌根真菌的多样性研究。其中,黄花杓兰(Cypripedium flavum)、少花鹤顶兰(Phaiusdelavayi)、二叶匍茎兰(Galearis diantha)和广布小蝶兰(Ponerorchis chusua)分布在开阔生境;筒距兰(Tipularia szechuanica)、小花舌唇兰(Platanthera minutiflora)、珊瑚兰(Corallorhiza trifida)和尖唇鸟巢兰(Neottia acuminate)则分布在密林生境。通过对分离所得的50个菌株进行形态观察和ITS序列测定相结合的鉴定,共获得菌根真菌41种。对担子菌和子囊菌分别进行的系统发育树构建结果显示,子囊菌为优势种类(35种),以柔膜菌目(Helotiales)、炭角菌目(Xylariales)和肉座菌目(Hypocreales)内的种类为主,担子菌则以胶膜菌(Tulasnellaceaesp.)为主。在8种兰科植物中,二叶匐茎兰表现出极高的专一性,其菌根真菌均属于Hypocrea。其余兰科植物的菌根真菌分别属于不同的科,专一性相对较低。物种丰富度和Simpson多样性指数分析结果表明,密林生境的兰科植物的菌根真菌多样性在各生长季节基本高于开阔生境。此外,两种生境的优势兰科植物的菌根真菌物种多样性随生长季节转变所呈现的变化规律是相似的:萌发期和生长期的多样性均较高,峰值出现在生长期,到果期时则大幅下降。这与高原兰科植物的生长特性及营养供求规律基本相符。     

北京松山国家级自然保护区兰科植物多样性及其保护评价

选取北京松山国家级自然保护区开展兰科植物多样性调查和分析,评估其保护现状。松山共有兰科植物12属18种,其中北方盔花兰为北京新记录种。在生活型方面,以地生兰为主,计14种（77．78％）,腐生兰4种（22．22％）;在分布区类型方面,属的区系成分以北温带分布为主（6属,5000％）,兼有旧世界温带分布（3属,25．00％）、世界分布（2属,16．67％）和旧世界热带分布（1属,8．33％）;种的区系成分以东亚分布为主（9种,50．00％）,兼有旧世界温带分布（5种,27．78％）和北温带分布（4种,22．22％）。松山兰科植物集中分布于北沟和小海坨山。通过综合分析松山兰科植物保护现状,提出生境评估、种群动态监测、建立迁地保护资源圃和加大宣传等都是切实加强兰科植物保护工作的可行措施。     

喀斯特地区不同类型兰科植物的叶片性状

叶片性状能够反映植物对环境的适应.认识喀斯特地区兰科植物的叶片性状及其适应意义对其科学合理的保育具有重要参考价值.本文于干季与雨季研究了广西雅长兰科植物自然保护区内落叶、常绿地生、常绿石附生三种类型共19种野生兰科植物的叶片性状及其相互关系,并比较了不同类型兰科植物之间的差异.其中18种兰科植物为C3植物,仅棒叶鸢尾兰(Oberonia myosurus)为CAM植物.相比于落叶兰,常绿兰具有较高的比叶重( LMA)和叶片碳氮比(C/N),但其叶片氮、磷含量较低.在常绿兰科植物中,石附生兰的叶片Ca含量与δ13C高于地生兰.石附生兰的叶片磷含量在雨季要高于干季,而地生兰的叶片δ13C在于季要高于雨季.该地区常绿兰科植物的N/P值＞16,表明其可能受到磷的限制.     

菌根真菌与兰科植物互作的组学研究进展

兰科植物因其具有丰富的物种多样性和重要的社会经济价值,多年来一直是植物学及生态学界的重点研究对象.菌根真菌对兰科植物的种子萌发、营养吸收和种群动态等多个方面都具有十分重要的作用,因而近年来受到越来越多的关注.探究菌根真菌与兰科植物互作的内在机制是目前兰科菌根研究的一大热点领域,同时也为兰科植物野生资源保护和种群恢复提供...     

腐生型兰科植物研究进展

腐生型兰科植物又称完全菌根异养型兰(Fully Mycoheterotrophic Orchids),无绿叶,不含叶绿素,不能进行光合作用制造有机物,完全依靠与其共生的真菌提供营养。近年来,腐生兰独特的生活方式引起了生物学家对其生理生态及进化问题的广泛关注,但目前仍缺乏系统深入的研究。为此,作者通过整理《中国植物志》和近年来报道的相关文献,发现分布在中国的腐生型兰科植物约有23属81种,主要集中在天麻属(Gastrodia)(24种)、鸟巢兰属(Neottia)(8种)、无叶兰属(Aphyllorchis)(6种)、山珊瑚属(Galeola)(5种)等。由于腐生兰特殊的营养需求,相比于其他营养类型的兰科植物,其菌根真菌有较大区别。腐生兰的菌根真菌主要有两大类,即外生菌根真菌(Ectomycorrhizal fungi,ECM)和非丝核菌类的腐生菌(Non-rhizoctonia SAP fungi)。该文还综述了腐生兰与其菌根真菌的专一性、营养来源以及系统进化等问题,提出了目前研究存在的问题,并对今后的研究工作进行了展望,以期为腐生兰的资源保护及再生研究提供参考。