Phylogenetic Relationships of Maples (Acer L.; Aceraceae) Implied by Nuclear Ribosomal ITS Sequences

Acer. ITS 1 sequences in twenty-eight species of Acer and a species of Dipteronia in the family Aceraceae ranged from 220 to 242 bp and ITS 2 sequences from 215 to 251 bp. The size of the 5.8S coding region was 164 bp for all species examined in the family. Phylogenetic analysis of ITS sequences placed a very robust clade of section Palmata at the base of the tree. Three species of section Parviflora sensu de Jong (1994), A. spicatum, A. distylum and A. nipponicum, did not form a monophyletic clade. Acer spicatum was separated from the robust clade of A. distylum and A. nipponicum. Molecular tree strongly supports the close relationship among section Platanoidea, Glabra series Arguta, and section Macrantha. The close relationship between sections Pentaphylla and Trifoliata was also strongly suggested in ITS tree. Sections Rubra and Hyptiocarpa appeared to be closely allied with each other. The average rate of nucleotide substitution was estimated as (8.0±1.9)×10⁻¹¹ substitutions per site per year for ITS 1 and (9.0±1.6) ×10⁻¹¹ for ITS 2. Received 17 December 1999/ Accepted in revised form 10 March 2000     

山羊草属二倍体物种核rDNA ITS区序列及其系统发育关系分析

测定了山羊草属（Ａｅｇｉｌｏｐｓ）二倍物种核ｒＤＮＡ ＩＴＳ区序列,发现其碱基粉介于６０１－６０７之间,比报道的小ｒｉｕｃｅａｅ）其他属的ＩＴＳ区我略长,Ｇ＋Ｃ含量达６１．１％～６２．９％,序列间的分化距离为０．００５０～０．０４６８。用ＰＨＹＬＩＰ３．５ｅ软件包对所测得的ＤＮＡ数据进行聚类分析,结果显示：１．Ａｅ．ｓｐｅｌｔｏｉｄｅｓ与该组其他种相距很远,支持将其从Ｓｉｔｏｐｓｉｓ组中独立出来,     

Circumscription and lectotypification of Cycas rumphii (Cycadaceae)

The misapplied nameCycas rumphii Miquel is demonstrated to be based on discordant elements, and is lectotypified by excluding the discordant elements of the protologue. Synonymy and misapplications of the name are provided.     

New species and a new record of Cycas (Cycadaceae) from Thailand

Two newCycas species from Thailand are here described.C. petraea andC. elephantipes. A noteworthy extensions of the range ofC. macrocarpa into southeastern Thailand is recorded. New taxa are illustrated, distributions of the new taxa are mapped, and a key to the species ofCycas in Thailand is provided.     

海南岛苏铁属一新种

海南岛苏铁属（苏铁科）一新种,即三亚苏铁。     

Genetic diversity of symbiotic cyanobacteria in Cycas revoluta (Cycadaceae)

The diversity of cyanobacterial species within the coralloid roots of an individual and populations of Cycas revoluta was investigated based on 16S rRNA gene sequences. Sixty-six coralloid roots were collected from nine natural populations of cycads on Kyushu and the Ryukyu Islands, covering the entire distribution range of the species. Approximately 400?bp of the 5'-end of 16S rRNA genes was amplified, and each was identified by denaturing gradient gel electrophoresis. Most coralloid roots harbored only one cyanobiont, Nostoc, whereas some contained two or three, representing cyanobiont diversity within a single coralloid root isolated from a natural habitat. Genotypes of Nostoc within a natural population were occasionally highly diverged and lacked DNA sequence similarity, implying genetic divergence of Nostoc. On the other hand, Nostoc genotypes showed no phylogeographic structure across the distribution range, while host cycads exhibited distinct north-south differentiation. Cycads may exist in symbiosis with either single or multiple Nostoc strains in natural soil habitats.     

贵州苏铁根的解剖学研究

对贵州苏铁（Cycas guizhouensis K.M.Lan et R.F.Zou）的根进行了解剖学研究,结果表明：（1）据外部形态和内部结构不同,贵州苏铁的根可分为正常根、珊瑚状根和肉质根三种类型。（2）正常根与肉质根的木栓形成层起源于表皮内方第1～2层皮层薄壁细胞,珊瑚状根的木栓形成层则起源于外方皮层的第2～3层细胞,而非中柱鞘。（3）首次发现肉质根一种新的增粗方式,是由周皮内方的皮层薄壁细胞恢复分裂能力,持续或周期性产生新的皮层薄壁细胞,引起根的增粗。     

ISSR variation in the endemic and endangered plant Cycas guizhouensis (Cycadaceae)

BACKGROUND AND AIMS: Cycas guizhouensis (Cycadaceae) is a rare and endangered species endemic to the southwest of China. An investigation was undertaken into the genetic variation of wild populations. METHODS: ISSR markers were used to determine the genetic variation within and between 12 extant populations of this species. KEY RESULTS: Low genetic diversity (at population level, P = 14.21 %, H(E) = 0.0597; at species level, P = 35.90 %, H(T) = 0.1082) and a high degree of differentiation among populations (G(ST) = 0.4321) were detected. CONCLUSIONS: This genetic structure is considered to be due to the combined effects of slow biochemical evolution, genetic drift, inbreeding and limited gene flow between populations. Based on these findings, strategies are proposed for the genetic conservation and management of the species.     

Development of seven novel EST-SSR markers from Cycas panzhihuaensis (Cycadaceae)

? Premise of the study: Cycas panzhihuaensis L. Zhou & S. Y. Yang is a vulnerable gymnosperm endemic to China, where its range represents the northernmost occupation of Cycas L. We developed EST-derived SSR markers to investigate its genetic diversity and population structure. ? Methods and Results: Based on the expressed sequence tag (EST) database for Cycas rumphii Miq., seven simple sequence repeat (SSR) markers were identified and screened in 55 individuals from seven wild populations of C. panzhihuaensis. Alleles numbered 2 to 5, and their observed heterozygosity and expected heterozygosity ranged from 0.0000 to 0.6545 and from 0.0535 to 0.6966, respectively. ? Conclusions: These new EST-SSR markers will enhance further studies of the population genetics of C. panzhihuaensis, allowing researchers to design reasonable conservation and management protocols.     

Isolation and characterization of microsatellite loci in endangered Cycas changjiangensis (Cycadaceae)

Eight microsatellite loci were isolated from repetitive DNA enriched libraries for Cycas changjiangensis, an endangered endemic species in Hainan Island, China. The number of allele ranged from three to seven. The observed (H _O) and expected (H _E) heterozygosities ranged from 0.0000 to 0.8750 and from 0.2359 to 0.7582, respectively. These microsatellite loci will enrich our scientific understanding for C. changjiangensis conservation.     

Maternal inheritance of plastids and mitochondria in Cycas L. (Cycadaceae)

Cycas is often considered a living fossil, thereby providing a unique model for revealing the evolution of spermatophytes. To date, the genetic inheritance of these archaic plants is not fully understood. The present study seeks to document the process of organelle inheritance in an interspecific cross of Cycas species. Extranuclear organelle DNA from chloroplasts and mitochondria was analyzed using both polymerase chain reaction-restriction fragment length polymorphism analysis and microscopy. Here, we show that the chloroplasts and mitochondria in the progeny of interspecific crosses between Cycas taitungensis and Cycas ferruginea were exclusively inherited from the female parent. Epifluorescence microscopic analyses of the pollen cells from Cycas elongata indicated that there was a significant degradation of organelle DNA in male reproductive cells following maturation; the DNA fluorescent signals were only seen after pollen mitosis two, but not detectable at mature stage. Lack of organelle DNA fluorescent signal in prothallial cells was confirmed by the absence of plastids and mitochondria in electronic microscopic images. In conclusion, these data suggest that the maternal plastid and mitochondrial inheritance in Cycas, native to the old world, are the same as seen in seed plants.     

Phylogenetic Relationships of the Far Eastern Araliaceae Inferred from ITS Sequences of Nuclear rDNA

In eight species of the family Araliaceae, inhabiting the territory of the Russian Far East, the sequences of ITS regions of nuclear rDNA were determined. A comparison of these sequences enabled establishment of phylogenetic relationships between the Far Eastern and other members of the family. It was demonstrated that Aralia elata populations from Primorye and Sakhalin were genetically different and, hereby, could be classified as intraspecific taxa. Aralia continentalis along with A. cordata were attributed to the section Aralia sensu Wen. Oplopanax elatus and O. horridus were found to be very close to each other, possibly being the subspecies of one species or relatively young species. Legitimacy of the discrimination between two sections within the genus Eleutherococcus was confirmed.__________Translated from Genetika, Vol. 41, No. 6, 2005, pp. 800–810.Original Russian Text Copyright © 2005 by Artyukova, Gontcharov, Kozyrenko, Reunova, Zhuravlev.     

Scanning electron microscopy studies of cuticle micromorphology in Cycas L. (Cycadaceae)

Abstract

A scanning electron microscopy (SEM) study of Cycas cuticle characteristics was undertaken in order to expand our knowledge of microscopic characters not observable under light microscopy and to clarify unresolved affinitites among some species within the genus. Whole leaf and isolated cuticle specimens from the middle region of leaflets of greenhouse-grown plants of Cycas revoluta, Cycas rumphii, Cycas circinalis, Cycas media, and Cycas normanbyana were examined using SEM for interior and exterior features. Characteristics in common include hypostomy, hair bases on abaxial and adaxial surfaces, adaxial cells randomly arranged, adaxial exterior cuticle smooth, and stomata sunken to various degrees but stomatal pit always formed by two layers of epidermal cells. Stomatal complex is of the polyperigenous type. Stomata randomly dispersed and oriented, and except C. revoluta, are not contiguous. Stomata deeply sunken in C. revoluta, intermediate in C. rumphii and C. normanbyana, and less sunken in C. circinalis and C. media. Aperture between guard cells extends the entire stomatal length in C. rumphii and C. normanbyana, ～80% in C. circinalis and C. media, and ～50% in C. revoluta. Cuticular features of C. revoluta show the greatest difference from the other species in complex relief of exterior cuticle and interior cuticular structure of subsidiary cells; C. media and C. circinalis show close similarity to each other and their stomatal complex dimensions fall within the same unique cluster using principal component analysis under normalized variables. C. normanbyana and C. rumphii show the most similarity to each other in cuticular micromorphology. Stomatal complex dimensions of these two species fall into a second cluster that also includes C. revoluta. These data contrast with current taxonomy placing C. normanbyana synonymous to C. media.     

Phylogenetic inferences in Antennaria (Asteraceae: Gnaphalieae: Cassiniinae) based on sequences from Nuclear Ribosomal DNA internal transcribed spacers (ITS)

The phylogenetic relationships among sexually reproducing species of Antennaria (Asteraceae) are poorly understood. An earlier cladistic analysis based on morphology did not fully resolve the phylogeny of these taxa and therefore a different approach using molecular data was explored. The internal transcribed spacer regions (ITS-1 and ITS-2) of nuclear ribosomal DNA were sequenced for 30 species of Antennaria and one species from each of the outgroup genera Anaphalis, Ewartia, Leontopodium, and Pseudognaphalium. The ITS-1 sequence in Antennaria ranged from 253 to 260 base pairs (bp) in length, and the proportion of nucleotide differences between pairs of species of Antennaria ranged from 1 to 14%. For ITS-2, the divergence between pairs of species of Antennaria ranged from 0 to 8%. ITS-2 is shorter than ITS-1, ranging from 213 to 219 bp. Phylogenetic analysis indicates that, relative to the outgroups included, Antennaria is a well-supported monophyletic group. Based on the genera surveyed, Leontopodium appears to be the sister genus of Antennaria. The general topology of the molecular trees agrees with that based on previous morphological analyses and indicates that Antennaria is composed of six clades of equal rank, corresponding to the traditionally recognized informal groups, the Geyeriae, Argenteae, Arcuatae, Dimorphae, Pulcherrimae, and Catipes. Sequence and morphological data indicate that the Alpinae and Dioicae are unnatural, polyphyletic units that should be abandoned and redefined as the monophyletic Catipes group. Phylogenetic analysis of ITS sequences also suggests the dissociation of A. stenophylla from the Dimorphae, where it is traditionally placed, and its affiliation with the Argenteae, as well as the placement of A. arcuata in its own group.     

基于rDNA-ITS2序列的中国按蚊属塞蚊亚属部分种类的系统发育研究(双翅目:蚊科)

应用rDNA-ITS2序列,采用邻接法(NJ)、最大简约法(MP)和最大似然法(ML),以按蚊亚属Anopheles的中华按蚊An.(An.)sinensis和赫坎按蚊An.(An.)hyrcanus为外群,对采自中国的按蚊属Anopheles塞蚊亚属Cellia 21种蚊进行了系统发育分析.结果表明:rDNA-ITS...     

Genetic differentiation and relationships of populations in the Cycas balansae complex (Cycadaceae) and its conservation implications

BACKGROUND AND AIMS: The Cycas balansae complex is arguably a controversial group with regard to species delineation. Some taxonomists recognize a single polymorphic species while others distinguish five narrowly defined ones. The unresolved taxonomy has the potential to bring about significant problems for species conservation. Thus, an investigation to examine the genetic diversity and differentiation in the C. balansae complex was performed to determine the relationship of populations and to test whether the morphologically defined segregations represent genetically distinct units. METHODS: Inter-simple sequence repeat (ISSR) markers were employed to assess the genetic diversity in the C. balansae complex with a sample of 158 individuals from all extant populations in China. KEY RESULTS: ISSR markers revealed low genetic diversity in all populations studied (H(E) and H(O) averaged 0.0639 and 0.0798 at the population level, respectively). Phenetic analysis showed that the C. balansae complex grouped into five clusters closely corresponding to the narrowly defined C. balansae, C. parvula, C. shiwandashanica, C. tanqingii and C. simplicipinna. CONCLUSIONS: ISSR data suggest that the C. balansae complex has evolved into five genetically distinct units. These might be derived from a relatively widespread common ancestor through multiple vicariant events including geographical isolation resulting from the collision of the Indian plate with the Eurasian plate and from Pleistocene glaciations. In conservation, attention should be paid to each genetic unit.     

Genetic Variation in the Endangered Endemic Species Cycas fairylakea (Cycadaceae) in China and Implications for Conservation

Cycas fairylakea is an endangered endemic species in China. Genetic diversity within and among four natural populations of this species in China was investigated using amplified fragments length polymorphism (AFLP). A moderate to low level of intraspecific genetic diversity was detected in this species (at population level: P = 39.57 %, H₀ = 0.244; at species level: P = 60.22%, H₀ = 0.356). The among-population component accounted for, respectively, 25.7 and 31.5% of the genetic variation, according to AMOVA and Shannon’s index, indicating most of the genetic variation was found between individuals within populations. All four populations have opposite pyramid age structure, and few coning individuals, which is still decreasing. Possibly because of habitat degradation and environmental pollution, plant diseases and insect pests in the populations were extremely serious, suggesting that the main factors threatening the survival of C. fairylakea populations were not genetic variation, but human activities and the breeding system of this species.     

由5个DNA片段推断极度濒危植物五针白皮松的系统位置

五针白皮松(Pinus squamata X. W. Li)是上世纪90年代描述的一种中国特有松树,目前野外只有立木32株,处于极度濒危状态.前人认为这个种可能是白松亚属(subgen. Strobus)的白皮松(P. bungeana Zucc. ex Endl.)与松亚属(subgen. Pinus)的云南松(P. yunnanensis Franch.)的过渡类型,并将其归入白皮松组狐尾松亚组(subsect. Balfourianae).本文试图在前人分子系统学工作的基础上,检测五针白皮松5个DNA片段,叶绿体基因rbcL、matK、rpl20-rps18间隔区和trnV 内含子以及核糖体ITS,将五针白皮松放在整个松属中探讨其系统位置.4个叶绿体基因单独分析结果和它们的联合数据分析结果以及根据ITS得到的系统树均表明,五针白皮松是白皮松亚组(subsect. Gerardianae)的一个稳定成员,其可能的姐妹群是西藏白皮松(P. gerardiana Wall.).对白皮松亚组的地理分布作了初步探讨.     

由5个DNA片段推断极度濒危植物五针白皮松的系统位置

五针白皮松(Pinus squamata X．W．Li)是上世纪90年代描述的一种中国特有松树,目前野外只有立木32株,处于极度濒危状态。前人认为这个种可能是白松亚属(subgen．Strobus)的白皮松(P．bungeana Zucc．ex Endl．)与松亚属(subgen．Pinus)的云南松(P．yunnanensis Franch．)的过渡类型,并将其归入白皮松组狐尾松亚组(subsect．Balfourianae)。本文试图在前人分子系统学工作的基础上,检测五针白皮松5个DNA片段,叶绿体基因rbcL、matK、rpl20-rps18间隔区和trn V内含子以及核糖体ITS,将五针白皮松放在整个松属中探讨其系统位置。4个叶绿体基因单独分析结果和它们的联合数据分析结果以及根据ITS得到的系统树均表明,五针白皮松是白皮松亚组(subsect．Gerardianae)的一个稳定成员,其可能的姐妹群是西藏白皮松(P．gerardiana Wall．)。对白皮松亚组的地理分布作了初步探讨。