The chloroplast genome from a lycophyte (microphyllophyte), <Emphasis Type="Italic">Selaginella uncinata</Emphasis>, has a unique inversion,transpositions and many gene losses

We determined the complete nucleotide sequence of the chloroplast genome of Selaginella uncinata, a lycophyte belonging to the basal lineage of the vascular plants. The circular double-stranded DNA is 144,170 bp, with an inverted repeat of 25,578 bp separated by a large single copy region (LSC) of 77,706 bp and a small single copy region (SSC) of 40,886 bp. We assigned 81 protein-coding genes including four pseudogenes, four rRNA genes and only 12 tRNA genes. Four genes, rps15, rps16, rpl32 and ycf10, found in most chloroplast genomes in land plants were not present in S. uncinata. While gene order and arrangement of the chloroplast genome of another lycophyte, Hupertzia lucidula, are almost the same as those of bryophytes, those of S. uncinata differ considerably from the typical structure of bryophytes with respect to the presence of a unique 20 kb inversion within the LSC, transposition of two segments from the LSC to the SSC and many gene losses. Thus, the organization of the S. uncinata chloroplast genome provides a new insight into the evolution of lycophytes, which were separated from euphyllophytes approximately 400 million years ago. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

中国蕨类植物孢子形态的研究ⅩⅣ.卷柏科

利用扫描电镜对中国产卷柏科25种植物孢子形态进行了观察。结果显示:(1)卷柏科植物大孢子为球状四面体,辐射对称;具三裂缝,裂缝为孢子半径的1/2~3/4;极面观一般为三角圆形或近圆形,赤道面观为近圆形、近扇形或近椭圆形;极轴长为158~548μm,赤道轴长为196~675μm。(2)小孢子为球状四面体,辐射对称;具三裂缝,裂缝为孢子半径的1/2~3/4或几达赤道线;极面观一般为近圆形或三角圆形,赤道面观为近圆形或近扇形;极轴长为10~40μm,赤道轴长为17~63μm。(3)孢子表面具颗粒状、瘤状、疣状、刺状、棒状、网状、片状、疣块状和脑状纹饰。研究认为,孢子形态特征可以作为该科亚属及种的分类学依据。     

云南产8种卷柏科植物的孢子形态

利用光学显微镜和扫描电子显微镜首次观察了云南产8种卷柏科(Selaginellaceae)植物：钝叶卷柏Selaginella amblyphylla Alston;双沟卷柏S．bisulcata Spring;勃固卷柏S．kwrzii Baker;疏穗卷柏S．laxistrobilis K．H．Shing;微齿钝叶卷柏S．ormata(Hook．et Grev．)Spring;耳叶卷柏S．pseudopaleifera Hand.-Mazz;高雄卷柏S．repanda（Desv．ex Poir)Spring;泰国卷柏S．siamensis Hieron．的大、小孢子形态。研究结果表明卷柏科植物大、小孢子为辐射对称、三裂缝,其表面纹饰复杂,8种卷柏植物的大、小孢子在孢壁纹饰上存在着较明显差异。为卷柏科形态学和系统演化的研究提供了有价值的基础资料。     

西藏产四种卷柏科植物的孢子形态观察

利用光学显微镜和扫描电子显微镜观察了西藏产4种卷柏科(Selaginellaceae)植物波密卷柏(Selaginella bomiensis Ching et S.K.Wu)、宽叶卷柏(S.megaphylla Baker)、墨脱卷柏(S.mutensis Ching)和钱形卷柏(S.nummularifolia Ching)的大、小孢子形态.扫描电镜观察结果显示:这4种卷柏科植物的孢子具有复杂的外部纹饰特征,且种间有很大的差异,可作为种间鉴别的重要分类依据.4种卷柏的孢子形态均为首次报道,为卷柏科系统演化及形态学研究提供有价值的基础资料.     

石松类卷柏科地史时期和现代地理分布格局的形成

卷柏科仅含一属,全球分布,具有宽幅生态适应性,属于维管植物基部类群石松类植物,现生约700种。卷柏科起源于泥盆纪,化石记录遍布自石炭纪至今的各地质时期。目前,现代卷柏属亚属的分类方案基本稳定,但对于化石卷柏的亚属分类、以及地质历史时期的时空分布问题还缺乏相关研究。本文全面总结了卷柏科化石记录的时代和地理分布,并结合分子系统学探讨其地理分布格局的演化,为该科植物的分类与进化研究提供参考。根据现有研究基础,结合最新的卷柏科系统分类研究成果和化石记录,本文对该类群化石的系统分类进行归纳和厘定,并对化石类群的卷柏亚属Selaginella、Hexaphyllum亚属及rhizophoric clade物种的分化和地理分布格局的形成进行了讨论。本文认为,卷柏科起源于古生代的欧美植物区,不晚于二叠纪,其后伴随着泛大陆解体扩散至华夏植物区及冈瓦纳植物区。化石亚属Hexaphyllum是rhizophoric clade的基部类群,在石炭纪末灭绝。化石证据表明,从古生代末期起,rhizophoric clade已成为卷柏科的优势类群,并在中生代形成了全球分布的格局。     

中国29种和泰国1种卷柏科植物的叶形态学研究及其分类学意义

利用光学显微镜和体视显微镜对卷柏科Selaginellaceae中国产29种和泰国产1种植物的叶形态进行了宏观和微观观察。结果表明卷柏科植物在叶形态学方面表现出较高的一致性。(1)叶多为二形, 罕为一形, 无叶柄, 叶二形者侧叶多大于中叶, 外展或斜上, 中叶贴生于腹面茎上, 交互覆瓦状排成4列, 叶一形者则在茎上作螺旋状排列。(2)侧叶与中叶上表皮细胞形态相似, 近等径方形或长方形, 垂周壁平直、弓形或波状; 侧叶与中叶下表皮细胞形态也相似, 长方形或长条形, 垂周壁波状。(3)气孔类型为无规则型或放射型, 气孔多分布于中叶上表皮和侧叶下表皮中脉处。研究发现, 叶外形、叶表皮细胞形态及气孔分布特征等为中国卷柏科植物种间分类提供了重要的参考依据。 研究的有关种类可以依据下面这些特征进行分类: (1)叶为一形叶或二形; (2)叶在枝上着生为螺旋状或成对交互排列; (3)叶表皮细胞垂周壁为平直、弓形、深波状或浅波状; (4)叶上、下表皮细胞同形或异形; (5)气孔为无规则型或放射型; 以及(6)气孔在中叶和侧叶的上、下表皮上的分布等特征。     

贵州卷柏属(卷柏科)一新种——习水卷柏

描述了贵州卷柏属一新种,即习水卷柏Selaginella xishuiensis G. Q. Gou &; P. S. Wang。新种与蔓出卷柏S. davidii Franch.在体态和大小方面相近,但叶缘具睫状毛而不同;新种在体态上也与地卷柏S. prostrata H. S. Kung相似,但孢子叶一型而不同。     

The phylogenetic history of Selaginellaceae based on DNA sequences from the plastid and nucleus: extreme substitution rates and rate heterogeneity

Molecular phylogenetic research on Selaginellaceae has focused on the plastid gene rbcL, which in this family has unusually high substitution rates. Here we develop a molecular data set from the nuclear 26S ribosomal DNA gene with the aim of evaluating and extending the results of previous phylogenetic research. The 26S rDNA and the rbcL regions were sequenced for a sample of 23 species, which represent the main elements of species diversity in the family. The data were analysed independently and in combination using both maximum parsimony and Bayesian inference. Although several between genome differences were found, the general pattern of relationships uncovered by all analyses was very similar. Results corroborate the previous study supporting new groupings not previously recognised on morphological grounds. Substitution rates in the 26S rDNA were also found to be high (26% informative) for the region analysed, but lower than for rbcL (37% informative). These data indicate that high substitution rates might be widespread in all three genomes (i.e., plastid, mitochondrion, and nucleus).