水杉是北美红杉的一个亲本吗？

本文根据有关细胞学和形态学资料.不同意Schlarbaum等以红杉没有水杉的具长着丝点区域的标记染色体来否定水杉(属)是红杉的亲本,同时认为,他们提出某种杉木属植物为红杉提供了染色体组而是它的亲本的意见难以成立,从而支持Stebbins的假设,水杉(属)可能是北美红杉的一个亲本。而且,它或许还是一个父本。     

北美红杉的一个亲本是灭绝的吗?

本文作者对Stebbins的"水杉和红杉的染色体及亲缘关系"一文进行了评述, 认为红杉除水杉(属)以外的另一个二倍体亲本可能并没有灭绝, 它或许就是巨杉(属).     

北美红杉的染色体组组成及其亲本

本文对Schlarbaum等认为红杉是染色体组组成为A₁A₁A₁A₁A₂A₂的部分异源多倍体、它的亲本是某个为其提供了染色体组的杉木属植物的意见提出了异议。无论从核型比较还是形态学特征来看, 红杉的染色体组组成似应为AAAABB而不是A₁A₁A₁A₁A₂A₂, 杉木属植物不可能是红杉的亲本, 后者可能是"水杉"和"巨杉"。     

从核型看北美红杉的起源

本文分析了同源异源自然六倍体北美红杉的AA和B染色体组的组型,它们属Stebbins的“1A”和“1B”,经与杉科各属植物的核型比较后发现分别与相同类型的水杉和巨杉最为接近,因而认为水杉属和巨杉属的某个古代种可能是北美红杉的二个杂交亲本,水杉和巨杉则或许是它们的后裔或近缘。本研究支持Stebbins认为水杉属的某个古代种是红杉的一个祖先而水杉是它的直接后裔的假设,但与他认为另一个祖先已经灭绝并没有留下近缘的推测存在分歧。     

北美红杉起源的时间和地点的探讨

根据笔者认为的北美红杉的亲本可能是分别以水杉、巨杉为直接后裔或留下近缘的水杉属和巨杉属的二个古代种及Florin的古植物学资料,本文推测北美红杉这个AAAABB同源异源多倍体(autoallopolyploid)杂交起源的时间和地点有三种可能:(1)中新世的美国西部(以俄勒冈州及其附近为中心);(2)古新世的格陵兰岛西海岸;(3)晚白垩纪的美国中西部(包括怀俄明州、科罗拉多州)。其中第一个推测的可能性更大。     

巨杉可能是红杉的一个祖先吗?

世界闻名的珍稀植物红杉Sequoia sempervirens是裸子植物中唯一染色体倍性最高的自然多倍体(2n=6x=66),植物学工作者一直十分关注着它的起源问题。Hirayoshi &Nakamura认为巨杉Sequoiadendron giganteum可能为红杉提供了一个染色体组,但Stebbins在假设一个古代水杉属Metasequoia植物可能是同源异源多倍体(autoallopoly-     

杉科的细胞分类学和系统演化研究

根据杉科的核型资料,本文(1)提出“1B”可能是一个新的高等植物核型类型;(2)讨论了各属的有关分类学问题及相互亲缘关系,它们的进化顺序可能是柳杉属、水松属、落羽杉属、水杉属、巨杉属、红杉属、杉木属(密叶杉属与之近缘)、台湾杉属;(3)支持金松属分立成金松科,它可能比杉科各属原始; (4)红杉(AAAABB)的亲本可能是二个古代种“水杉”和“巨杉”,它们的直接后裔或留下的近缘是水杉和巨杉;(5)杉科存在A和L两条进化路线,前者包括柳杉属、水松属、落羽杉属、台湾杉属;后者包括水杉属、巨杉属、红杉属、杉木属(密叶杉属);(6)提出一个杉科新系统(包括一个新亚科):Ⅰ.柳杉亚科(柳杉属),Ⅱ.落羽杉亚科(水松属、落羽杉属),Ⅲ.红杉亚科(水杉属、巨杉属、红杉属),Ⅳ.杉木亚科(杉木属、密叶杉属),Ⅴ.台湾杉亚科,新亚科(台湾杉属)。本文还对前人的杉科系统作了讨论。     

杉科的细胞分类学和系统演化研究

根据杉科的核型资料,本文(1)提出“1B”可能是一个新的高等植物核型类型;(2)讨论了各属的有关分类学问题及相互亲缘关系,它们的进化顺序可能是柳杉属、水松属、落羽杉属、水杉属、巨杉属、红杉属、杉木属(密叶杉属与之近缘)、台湾杉属;(3)支持金松属分立成金松科,它可能比杉科各属原始;(4)红杉(AAAABB)的亲本可能是二个古代种水杉”和“巨杉”,它们的直接后裔或留下的近缘是水杉和巨杉;(5)杉科存在A和L两条进化路线,前者包括柳杉属、水松属、落羽杉属、台湾杉属,后者包括水杉属、巨杉属、红杉属、杉木属(密叶杉属);(6)提出一个杉科新系统(包括一个新亚科)：I．柳杉亚科(柳杉属),II．落羽杉亚科(水松属、落羽杉属),III．红杉亚科(冰杉属、巨杉属、红杉属),Ⅳ.杉木亚科(杉木属、密叶杉属),V．台湾杉亚科,新亚科(台湾杉属)。本文还对前人的杉科系统作了讨论。     

水杉的核型研究

本文观察了水杉的染色体,确定2n=22,核型公式为K(2n)=22m(2SAT),全具中着丝点,有一对随体。第8、10、11号染色体具“长着丝点区域”。属“1A”型,与北美红杉-AA的核型非常相近,可能是它的一个亲本种的直接后裔。     

杉科的两条演化路线

本文根据核型资料提出杉科可能存在A、L两条演化路线,前者包括由原始到进化的柳杉属、水 松属、落羽杉属、台湾杉属,以平均臂比快速增加、染色体长度比缓慢增加为特征;后者包括依序进化的水杉属、巨杉属、红杉属、杉木属(可能还有密叶杉属),以平均臂比缓慢增加、染色体长度比迅速增加为特点。该结论也得到形态学、解剖学、胚胎学等资料的支持。     

Phylogenetic Analysis of the Family Taxodiaceae

In the present paper,both cladistic analysis and phenetic analysis were conducted to evaluate the phylogenetic relationships of the Taxodiaceae based on an extensive literature review and study of herbarium． In the cladistic analysis,the Sciadopityaceae was chosen as outgroup．The polarity of characters was determined mainly according to outgroup comparison,fossil evidence and generally accepted viewpoints of morphological evolution．By the result of compatibility analysis,character 2(leaf type),which possessed a much higher coefficient than others whether or not its polarity was altered,was deleted． Finally,a data matrix consisting of all the extant nine genera and 24 characters was analyzed using Maximal Same Step Method,Synthetic Method,Evolutionary Extremal Aggregation Method and Minimal Parallel Evolutionary Method,and four cladograms were generated,of which only the most parsimonious one (Fig．1)was presented for discussion. The cladogram shows that the Taxodiaceae are assorted along five lines of evolution： 1)Metasequoia;2)Sequoiadendron,Sequoia;3)Cryptomeria;4)Glyptostrobus and Taxodium;5)Cunninghamia,Athrotaxis and Taiwania． Ten genera(including Sciadopitys)and 59 characters were used in the phenetic analysis．The phenogram(Fig．2)indicates that Sciadopitys is a very distinct group with remote affinity to the other genera,and the Taxodiaceae are divided into four groups：1)Sequoia,Sequoiadendron;2)Athrotaxis,Cunninghamia and Taiwania;3)Cryptomeria,Glyptostrobus and Taxodium;4)Metasequoia． Based primarily on the result of cladistics,with reference to that of phenetics,the main conclusions were drawn as follows：(1)Generic relationships：Cryptomeria should be considered the most primitive genus in the extant groups of the Taxodiaceae. Glyptostrobus and Taxodium, close to Cryptomeria, are sister taxa and relatively primitive groups. Sequoiadendron and Sequoia are closely related and intermediate advanced. Metasequoia is a more or less isolated taxon, relatively close to Sequoiadendron and Sequoia. Cunninghamia. Athrotaxis and Taiwania might represent a single lineage and form a very advanced group, of which Taiwania may be the most specialized. (2) Systematic treatments: The authors support the viewpoint that Sciadopitys should be treated as an independent family, and suggest that the Taxodiaeae should be divided into five tribes. Systematic arrangements are as follows: Taxodiaceae Warming Trib. 1. Cryptomerieae Vierhapper Gen. 5. Sequoia Endl. Gen. 1. Cryptomeria D. Don Trib. 4. Metasequoieae Pilger et Melchior Trib. 2. Taxodieae Benth. et Hook. Gen. 6. Metasequoia Miki ex Hu et Cheng Gen. 2. Glyptostrobus Endl. Trib. 5. Cunninghamieae Zucc. Gen. 3. Taxodium Rich. Gen. 7. Cunninghamia R. Br. Trib. 3. Sequoieae Wettstein Gen. 8. Athrotaxis D. Don Gen. 4. Sequoiadendron Buchholz Gen. 9. Taiwania Hayata     

Seed cone and ovule ontogeny in Metasequoia, Sequoia and Sequoiadendron (Taxodiaceae–Coniferales)

TAKASO, T. & TOMUNSON, P. B., 1992. Seed cone and ovule ontogeny in Metasequoia, Sequoia and Sequoiadendron (Taxodiaceae–Coniferales). Structural features of seed cones, up to the initiation of ovules, are developed in the three genera in the summer and late fall prior to pollination in the following spring, when cones renew their further development. Bracts are initiated in a decussate manner in Metasequoia but spirally in Sequoia and Sequoiadendron. No ovuliferous scale is initiated, at most there is a shallow mound of tissue on the adaxial surface of the bract from which the ovules are developed. Metasequoia produces a single series of up to eight ovules in acropetal (centripetal order), Sequoia and Sequoiadendron produce a double series of six to nine ovules, also in acropetal order, since a second series of ovules appear distal to and alternate with the first series. Common features that unite the genera are the somewhat peltate configuration of the cone scales due to late intercalary expansion, the derivation of the vascular supply to the bract-ovule complex from a single bundle and the usual inversion of the seed during late development, to which can be added developmental features. The absence of tooth-like structures, present in some other Taxodiaceae, is discussed in relation to cone evolution in the family being determined by changes in developmental timing. Emphasis is made on the way in which features of morphogenesis, determine cone organization in the three genera independent of an interpretation that relies solely on hypothetical ancestral forms.     

杉科、柏科的系统发生分析——来自28S rDNA序列分析的证据

对杉科（Taxodiaceae）与柏科（Cupressaceae s.s.）的28S rRNA基因的部分序列（约630 bp）进行PCR扩增、序列测定和系统发生关系分析,用简约法和邻接法构建的系统发生树基本一致。结果表明,杉科与柏科构成一个单系群,支持将杉科、柏科（Sciadopitys除外）合并为一个科——广义柏科（Cupressaceae sensu lato）的观点。在广义柏科中,Taiwania、Athrotaxis分别形成一支系;Metasequoia、Sequoia、Sequoiadendron关系较近,聚成一支系; Taxodium、Glyptostrobus、Cryptomeria聚成一支系;柏科聚成一支系。这一分析结果与叶绿体基因序列的分析结果相吻合,但是由于28S rRNA基因的进化速率较慢,尚不能分辨上述各个支系之间的系统演化关系。 Abstract:DNA sequences from 28S rDNA were used to assess relationships between and within traditional Taxodiaceae and Cupressaceae s.s.The MP tree and NJ tree generally are similar to one another.The results show that Taxodiaceae and Cupressaceae s.s.form a monophyletic conifer lineage excluding Sciadopitys.In the Taxodiaceae-Cupressaceae s.s.monophyletic group,the Taxodiaceae is paraphyletic.Taxodium,Glyptostrobus and Cryptomeria forming a clade(Taxodioideae),in which Glyptostrobus and Taxodium are closely related and sister to Cryptomeria;Sequoia,Sequoiadendron and Metasequoia are closely related to each other,forming another clade (Sequoioideae),in which Sequoia and Sequoiadendron are closely related and sister to Metasequoia;the seven genera of Cupressaceae s.s.are found to be closely related to form a monophyletic lineage (Cupressoideae).These results are basically similar to analyses from chloroplast gene data.But the relationships among Taiwania,Sequoioideae,Taxodioideae,and Cupressoideae remain unclear because of the slow evolution rate of 28S rDNA,which might best be answered by sequencing more rapidly evolving nuclear genes.     

杉科植物的系统发育分析

本文以形态学为依据,参考其他学科的研究成果,用分支分类方法并结合表征分类方法探讨了杉科植物的系统演化关系,提出了新的分类系统。在分支分类中,金松科被选作外类群。主要根据外类群比较原则、化石原则和一般的演化规律,确定了性状的祖征和衍征,采用最大同步法、综合分析法、演化极端结合法及最小平行进化法共四种方法进行分支分析,选择最简约的分支图作为本文讨论基础。在表征分类中,选取59个性状,利用距离系数和类平均法,对金松属和杉科各属进行了聚类运算,得出表征图。综合两种分析结果,主要结论如下:(1)属间关系:柳杉属是现存杉科植物中最原始的类群。水松属和落羽杉属关系密切,二者与柳杉属近缘。巨杉属和北美红杉属关系密切,是中级进化水平的类群。水杉属与巨杉属和北美红杉属的亲缘关系相对较近。杉木属、密叶杉属和台湾杉属关系密切,是杉科植物中的高级进化类群,其中又以台湾杉属演化水平最高。(2)系统排列:支持金松科的成立,将杉科分成5族,即柳杉族(仅含柳杉属)、落羽杉族(含水松属、落羽杉属)、北美红杉族(含巨杉属、北美红杉属)、水杉族(仅含水杉属)和杉木族(含杉木属、密叶杉属及台湾杉属)。     

水杉栽培居群的遗传多样性研究

利用RAPD技术,对9个水杉(Metasequoiaglyptostroboides)栽培居群的遗传多样性进行了初步研究。用10bp的随机引物16条,共扩增出103个位点,其中37个为多态位点,占35.92%。各居群的多态位点百分率在16.50%~33.01%之间。POPGENEversion1.31软件处理结果如下:居群的Shannon’s信息指数为0.1930。遗传距离在0.0130~0.0650之间,遗传一致度在0.9370~0.9871之间。AMOVA分析结果显示遗传变异主要存在于居群内,占89.05%,居群之间有一定的分化。上述结果表明水杉栽培居群的遗传多样性略低于自然居群,涵盖了自然居群近80%的遗传多样性。由此可以确认栽培水杉的种源是经过混合的,它们在相当程度上代表了自然居群的遗传多样性水平。采自潜江的9株丛枝水杉(Metasequoiaglyptostroboidesvar.caespitosa)没有扩增出特有位点,将其视为一个居群根据遗传一致度作UPGMA聚类分析时,该居群和湖北的3个居群及南京(NJ)、成都(CD)居群聚在一起;单株聚类时丛枝水杉也没有聚成独立的一支,而是比较分散,因此不支持将丛枝水杉作为水杉的一个变种的分类处理。从亲缘关系上看,丛枝水杉应当归属于湖北潜江蚌湖种子园(BH)和湖北潜江广华(GH)居群,这与其分布现状也是吻合的。     

Two Evolutionary Lines of Taxodiaceae

According to the karyotypic data the present author proposes two evolutionary lines, A and L (Fig. 1), in Taxodiaceae (Exclud. Sciadopitys). The former is characterized by a relatively rapid increase of the mean arm ratio but a relatively slow rise of the ratio of the longest chromosome to the shortest one and it is composed of Cryptomeria, Glyptostrobus, Taxodium and Taiwania, which advance from primitive to progressive in the order. The latter is characterized by, on the contrary, a relatively slow increase of mean arm ratio and a relatively rapid rise of the ratio of chromosome size and it comprises Metasequoia, Sequoiadendron, Sequoia and Cunninghamia (probably Athrotaxis also), which advance in the order. The inference is supported by the data from morphology, anatomy, embryology and so on.Key words Taxodiaceae; Karyotype; Evolutionary line     

Phylogenetic relationships in Taxodiaceae and Cupressaceae sensu stricto based on matK gene, chlL gene, trnL-trnF IGS region, and trnL intron sequences

Nucleotide sequences from four chloroplast genes, the matK, chlL, intergenic spacer (IGS) region between trnL and trnF, and an intron of trnL, were determined from all species of Taxodiaceae and five species of Cupressaceae sensu stricto (s.s.). Phylogenetic trees were constructed using the maximum parsimony and the neighbor-joining methods with Cunninghamia as an outgroup. These analyses provided greater resolution of relationships among genera and higher bootstrap supports for clades compared to previous analyses. Results indicate that Taiwania diverged first, and then Athrotaxis diverged from the remaining genera. Metasequoia, Sequoia, and Sequoiadendron form a clade. Taxodium and Glyptostrobus form a clade, which is the sister to Cryptomeria. Cupressaceae s.s. are derived from within Taxodiaceae, being the most closely related to the Cryptomeria/Taxodium/Glyptostrobus clade. These relationships are consistent with previous morphological groupings and the analyses of molecular data. In addition, we found acceleration of evolutionary rates in Cupressaceae s.s. Possible causes for the acceleration are discussed.