摘要
本文研究了广义蓼属(Polygonum L.)以及相关属(Fallopia,Reynoutria,Antenoron,Fagopyrum和Pteroxygonum)的分子系统学、果实形态解剖学、花被片形态学。在此基础上,对中国的单型属Pteroxygonum进行了系统学位置的研究,主要研究结果如下:
果实形态解剖学研究结果表明,所观察的物种中外果皮常常加厚,并且可以根据外果皮细胞的垂周壁是否平直,可以明显的区分为平直型和波状两类,具有平直型垂周壁的外果皮细胞的主要特征是细胞为方形或者为高度为宽度的1.5-2倍的矩形,并拥有二叉状分枝的内腔,此种类型的我们所观察到的植物有Polygonum sect.Aconogonon和Polygonum sect.Bistorta。具有波状型垂周壁的外果皮细胞的主要特征是细胞为矩形,其高度为宽度的2倍-4倍,内腔为直的不分叉或者没有内腔,此种类型的我们所观察到的植物有sect.Persicaria,Antenoron,Polygonum sect.Echinocaulon和Polygonum sect.Cephalophilon。Fagopyrum具有较为特殊的外果皮形态,一种为外果皮不加厚,另外一种为外果皮加厚并有内腔分布。其他的类群没有发现一致的解剖学性状。
基于核糖体基因5.8S以及间隔片断ITS的序列分析,对36种蓼属及相关属进行了系统演化关系分析。研究结果表明由Fallopia,Reynoutria和Polygonum sect.Polygonum构成的Polygoneae(Ⅰ)这一支,与Fagopyrum,Koenigia,Polygonum sect.Bistorta,Polygonum sect.Cephalophilon,Polygonum sect.Persicaria,Antenoron以及Pteroxygonum组成的Persicarieae(Ⅱ)一支构成姐妹群。在Persicarieae中,Fagopyrum是最早分化的一个谱系,Pteroxygonum紧随其后分化出来,二者依次和Polygonum(except Polygonum sect.Polygonum)构成姐妹类群关系。在Polygonum(except Polygonum sect.Polygonum)这一支中分化出两大亚分支:一支是由Polygonum sect.Bistorta,Polygonum sect.Aconogonon和Koenigia组成,其中Polygonum sect.Aconogonon和Koenigia聚合成的B这一支与Polygonum sect.Bistorta的A这一支形成姐妹关系;两外一支是由Polygonum sect.Cephalophilon,Polygonum sect.Persicaria,Polygonum sect.Echinocaulon和Antenoron组成的,但是他们之间的关系并没有得到很高的支持率的支持。基于ITS的系统发育树的研究支持将蓼属于及相关属划分为个族来处理即tribes Persicarieae和Polygoneae。结合前人的观点,我们支持Koenigia是Polygonum sect.Aconogonon在高原地区的进化类型,并且承认Aconogonon属级位置的存在。针对Koenigia的物种范围,ITS分子系统同样选取了蓝药蓼Polygonum cyanandrum和大铜钱叶蓼Polygonum forrestii作为探讨Koenigia范围的物种,结果同atpB-rbcL所得到的结果一致即这两个种应置于冰岛蓼属,支持将这个类群作为一个属处理。根据ITS系统发育图,Polygonum sect.Bistorta这个类群植物与Polygonum sect.Aconogonon的亲缘关系较近即(A+B)这一支,建议将这两个类群的分类阶元上升为属,同时ITS系统发育树的结果表明Fagopyrum置于tribe Persicarieae中,并且位于基部位置,同意Ronse Decreane的观点即Fagopyrum是tribe Persicarieae的基部类群,不赞同Fagopyrum与Fallopia具有较近亲缘关系的观点。针对广义蓼属的范围问题,我们根据分子系统学的证据,认为应该成立Persicaria其下包括以下的几个组:sects.Echinocaulon,Cephalophilon,Persicaria,Tovara。本文特别讨论了Polygonum bungeanum的归属问题,根据形态学特征以及分子系统学的结果认为Polygonum bungeanum应该属于sect.Persicaria。在我们的ITS系统发育树上,由于I group中共包括了Fallopia和sect.Polygonum两个类群,也许是由于我们的分子生物学试验中sect.Polygonum的物种选择不多,所以导致了Polygonum sect.Polygonum插入到Fallopia支中。I group中Fallopia与Reynoutria聚为一支,所以我们更倾向于将Reynoutria作为Fallopia的一个组来处理,同时我们发现在I group中除了有些基部有支持率比较高的区分外,内部的各分支的自展支持率并不高,从而反映出这个属的分组状态从我们的ITS系统发育图中并不能很好的反映出来,有必要通过更多的物种和基因片断联合分析这个属的分组情况。
通过对翼蓼及相关属(蓼属、首乌属、虎杖属、荞麦属和金线草属)的形态观察、果实解剖学观察、花被片脉序观察、花粉形态、核型分析、以及ITS序列的分析确定了翼蓼和荞麦较远的亲缘关系。其中我们发现翼蓼果实基部有三个角物明显不同于其他属果实的形态特征。翼蓼外果皮明显加厚并有零星散布的波状内腔,而荞麦的外果皮很薄细胞不等径中果皮极厚。以上证据证明了翼蓼与荞麦属有较远亲缘关系。在观察荞麦属和翼蓼的花被片脉络时发现了两种不同的脉序类型,符合将荞麦属被分为两个组的划分。翼蓼花被片脉序为三出状,支持将翼蓼归为Persicarieae族。对翼蓼及荞麦属植的花粉进行了比较后,发现荞麦属植物的花粉网孔有明显的内凹穿孔而翼蓼却没有,结果表明二者较远的亲缘关系。通过对nrDNA ITS区域序列分析得出翼蓼及相关属为一个单系类群,含有两个稳定的分支:第一个分支由蓼属(萹蓄组)、首乌属、虎杖属的植物组成,第二个分支由蓼属(刺蓼组、蓼组、分叉蓼组、拳参组)、翼蓼和荞麦属植物组成。同时第二个分支又分成了两个亚分支,蓼属(刺蓼组、蓼组、分叉蓼组、拳参组)和翼蓼属植物属于第一个亚支而荞麦属植物植物属于第二个亚支。结果支持翼蓼不属于荞麦属的范畴。实验结果显示翼蓼是个单型属,并且属于Persicarieae族。
The phylogenetic relationships of Polygonum L. and related genera were comprehensively investigated using integrated studies on fruit anatomy and molecular phylogeny, along with field and herbarium investigations. The results are summarized as follows:
1. Anatomy of fruit
Sections of fruits, coupled with surface patterns were studied under LM in Polygonum L. and related genera. Based on the straight or undulating excocarp and the different lumen, two types of the excocarp cell can be recognized in the species studied. In typeⅠ, the excocarp is usually thickened and correlated with the straight or undulating outline of the anticlinal walls, and sections Persicaria, Tovara, Echinocaulon, and Cephalophilon of the genus that studied this investigation, its anatomy can be used consistently to delimit genera more than any other character of the fruit. In typeⅡ, Polygonum sect. Aconogonon and Polygonum sect. Bistorta which we investigated in this study can be delimited by the square to rectangular cells with a narrow dichotomously branching lumen and straight anticlinal walls; both genera share the same pattern of the structre of cell, have close relationship. Different structure of excocarp in species of Atraphaxis, Fallopia and sect. Polygonum can be found. Fagopyrum have two types of exocarps types: the thin exocarps and thick exocarp with dichotomously branching lumen corresponding to the two groups of Fagopyrum.
2. Molecular phylogeny
Phylogenetic analyses 36 species of Polygnoum s.l. and related genera based on sequence of the nrITS using maximum parsimony. The results of phylogenetic analyses suggest Polygonum s.l. related genera is not a monophyletic group, and correspond to division of Polygoneae and Persicarieae. Fagopyrum are nested within Persicarieae. It is noteworthy that Koenigia and Aconogonon compose a monophyletic group with a close relationship to Bistorta.
3. Reappraisal of the generic status of Pteroxygonum
Gross morphology, fruit anatomy, tepal venation, pollen morphology, chromosome number and ITS sequence of Pteroxygonum Damm. et Diels as well as other related genera (Polygonum., Fallopia, Reynoutria, Fagopyrum and Antenoron) have been investigated, to evaluate the generic status of Pteroxygonum. Pt. giraldii has three sharp horns at the base of fruit, which is distinctive among all the genera investigated. Upon observation of fruits under a light microscope (LM), the exocarp of Pt. giraldii is usually thickened and delimited by the rectangular cells with some sporadic undulating lumen, while that of Fagopyrum is thin-walled and isodiametric to rectangular in the cell shape. Analysis of tepal venation was performed under a stereomicroscope, and two types of tepal venation were found in Fagopyrum and Pteroxygonum. The typeⅠis trifid, observed in Pt. giraldii, F. esculentum Moench, F. dibotrys (D.Don) Hara and F. tataricum (L.) Gaertn. The typeⅡ, found in F. caudatum (Sam.) Harald, F. urophyllum (Bur. et Franch) H. Gross and F. gracilipes (Hemsl.) Hedb, has the main vein extending from tepal base with some secondary veins. Evidence from tepal venation supports the previous classification in which Fagopyrum can be divided into a large-achene group and a small-achene group. Pollen morphology was investigated under a scanning electron microscope (SEM). The exine ornamentation of Pt. giraldii was finely reticulate with lumina diameter wider than muri width. The exine ornamentation in all the examined Fagopyrum species is, however, prominently sunken punctuate. The phylogenetic analysis of nuclear ribosomal DNA (nrDNA) ITS sequences in Pteroxygonum and related genera indicated that all the species form a well-supported monophyletic group with two clades. One includes Polygonum sect. Avicularia Meisn., genus Fallopia and genus Reynoutria, and the other consists of other sections of Polygonum, genus Fagopyrum and Pteroxygonum. The latter clade can be divided into two subclades. Fagopyrum species compose the first one, while Pterxoygonum giraldii, Polygonum (except sect. Avicularia) and Antenoron form the second one. In consideration of the above evidence, we conclude that Pteroxygonum is an independent genus, in Tribe Persicarieae, and should not be merged into genus Fagopyrum.
引文
[1]Steward, A. N. The Polygonaceae of Eastern Asia. Contributions from the Gray Herbarium of Harvard University[J]. 1930,5(88): 1-129.
[2]K. Kubitzki et al., eds. 1990. The Families and Genera of Vascular Plants.[M]4+ vols. Berlin etc. Vol. 2, pp. 531-544.
[3]CraigC.Freemhttp://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=10717
[4]Li A. J. Flora of China 5: 277-350. 2003.
[5]Haraldson, K. Anatomy and taxonomy in Polygonaceae subfam. Polygonoideae Meisn. emend. Jaretzky[J]. Acta Univ. Upsal., Symb. Bot. Upsal, 1978.22: 1-93.
[6]Ronse Decraene, L.-P., Hong S. P., and E. Smets. Systematic significance of fruit morphology and anatomy in tribes Persicarieae and Polygoneae(Polygonaceae)[J]. Bot. J. Linn. Soc., 2000, 134:301-377
[7]Carlquist, S. Wood anatomy of Polygonaceae: Analysis of a family with exceptional wood diversity. Bot. J. Linn. Soc., 2003, 141:25-51.
[8]Hedberg O. Pollen morphology in the genus Polygonum L. s. lat. and its taxonomical significance[J]. Sven.Bot.Tidskr., 1946,40:371-404
[9]Nowicke & Skvarla. Pollen morphology and the relationship of the Plumbaginaceae, Polygonaceae, and Primulaceae to order Centrospermae[M]. Smithsonian Contributions to Botany, 1977:37:1-64
[10]张小平、周忠泽.中国蓼科花粉的系统演化[M].合肥:中国科学技术大学出版社1998.
[11]Hong, S. P., L.-P. Ronse Decraene, and E. Smets. Systematic significance of tepal surface morphology in tribes Persicarieae and Polygoneae(Polygonaceae)[J]. Bot. J. Linn. Soc., 1998, 127:91-116
[12]Ronse Decraene, L.-P. and J. R. Akeroyd. Generic limits in Polygonum and related genera(Polygonaceae) on the basis of floral characters[J]. Bot. J. Linn. Soc., 1988, 98:321-371
[13]Jaretzky, R. Beitrage zur Systematik der Polygonaceae unter Berücksichtigung des Oxymethyl-anthrachinon-Vorkom-mens[J]. Feddes Repertorium Specierum Novarum Regni Vegetabilis, 1925, 22:49-83
[14]Gross Remarques sur les Polygonees de Ⅰ' Asie Orientale. Bulletin de Geographic botanique, 23: 7-32.
[15] Kim, M. H., J. H. Park, and C. W. Park. Flavonoid chemistry of Fallopia section Fallopia (Polygonaceae) [J]. Biochem. Syst. & Ecol., 2000,28: 433-441.
[16] Love&Love. Chromosomes and taxonomy of Eastern North American Polygonum[J].Canadian Journal of Botany, 1956, 34:501-521.
[17] Love A, Sarkar P. Chromosomes and relationships of Koenigia islandica[J]a.Canadian Journal of Botany, 1957, 35 : 507- 514.
[18] Cuenoud, P., V. Savolainen, L. W. Chatrou, M. Powell, R. J. Grayer, AND M. Chase. Molecular phylogenetics of Caryophyllales based on nuclear 18S rDNA and plastid rbcL, atpB and matK DNA sequences. American Journal of Botany,2002, 89: 132-144
[19] Lamb Frye, A. S. and K. A. Kron. rbcL phylogeny and character evolution in Polygonaceae [J ]. Syst. Bot.., 2003, 28: 326-332.
[20] Yasui, Y and O. Ohnishi. Comparative study of rbcL gene sequences in Fagopyrum and related taxa[J]. Genes and Genetic Systems, 1996,71: 219-224.
[21] Yasui, Y and O. Ohnishi.. Interspecific relationships in Fagopyrum (Polygonaceae) revealed by the nucleotide sequences of the rbcL and accD genes and their intergenetic region[J]. American Journal of Botany, 1998a, 85: 1134-1142.
[22] Yasui, Y and O. Ohnishi. Phyiogenetic relationships among Fagopyrum species revealed by nucleotide sequences of the ITS region of the nuclear rRNA gene[J].Genes and Genetic Systems, 1998b, 73: 201-210.
[23] Holub, J., Fallopia Adans. 1763 instead of Bilderdykia Dum [J]. Folia Geobotanica a Phytotaxonomica Praha, 1970,6: 171-177
[24] Leeuwen P V, Punt W, Hoen P P. The Northwest European Pollen Flora-43.Polygonaceae. [J]Rev Palaeobot Palynol, 1988, 57: 81 — 151
[25] Zhou Zhongze, Lu Runlong , Zheng Yanyan. Parallel Evolution of Aperture Numbers and Arrangement of Polygonaceae in China[J]. Journal of China University of Science and Technology, 1999, 29(2). 195-198
[26] Kim, M. H., J. H. Park, and C. W. Park. Flavonoid chemistry of Fallopia section Fallopia (Polygonaceae) [J]. Biochem. Syst. & Ecol., 2000, 28: 433-441.
[27] Kim, M. H., J. H. Park, H. Wang and C. W. Park. Flavonoid chemistry and chromosome numbers of Fallopia section Pleuropterus (Polygonaceae) [J]
[28] Bentham, G. & Hooker, J. D., Polygonaceae. Genera Plantarum[M],3(1). London: L. ,1880, Reeve & Co.
[29]Roberty, G. & Vautier, S., Les genres de Polygonacees.[J]Boissiera, 1964, 10; 7-127
[30]Webb, D. A. & Chater, A. O., Genetic limits in the Polygonaceae. In V. H. Heywood(Ed.), Flora Europaea: Notulae systematicae no. 2. Feddes Repertorium Specierum nouarum Regni Vegetabilis, 1963, 68:187-189
[31]Danser, B. H. Die Polygonaceen Niederlandisch Ostindiens[J]. Bulletin du Jardin botanique. Buitenzorg, 1927, 3(8): 119-261
[32]Graham, S.A. & Wood, C. E. The genera of Polygonaceae in the South Eastern United States[J]. Journal of the Arnold Arboretum, 1965, 46:91-121
[33]Hong S. P. Knorringia(Aconogonon sect. Knorringia), a new genus in the Polygonaceae[J]. Nordic Journal of Botany, 1989, 9:343-357
[34]Ohnishi, O., and Matsuoka, M. Search for the wild ancestor of buckwheat. Taxonomy of Fagopyrum(Polygonaceae) species based on morphology, isozymes and cpDNA variability[J]. Genes Genet. Syst., 1996, 71,383-390
[35]Yasui, Y. and O. Ohnishi. Phylogenetic relationships among Fagopyrum species revealed by the nucleotide sequences of the ITS region of the nuclear rRNA gene[J]. Genes Genet. Systems, 1998, 73: 201-210.
[36]Yasui, Y. and O. Ohnishi. Interspecific relationships in Fagopyrum(Polygonaceae) revealed by the nucleotide sequences of the rbcL and accD genes and their intergenic region[J]. Amer. J. Bot., 1998b, 85:1134-1142.
[37]Ohsako, T., and Ohnishi, O. Intra-and interspecific phylogeny of wild Fagopyrum(Polygonaceae) species based on nucleotide sequences of noncoding regions in chloroplast DNA[J]. Am. J. Bot., 2000, 7, 573-582.
[38]Ohsako T., Fukuoka, S., Bimb, H, P., Baniya, B, K., Yasui, Y., and Ohnishi, O. Phylogenetic analysis of the genus Fagopyrum(Polygonaceae), including the Nepali species F. megacarpum, based on nucleotide sequence of the rbcL-accD region in chloroplast DNA[J]. Fagopyrum, 2001, 18, 9-14.
[39]汪小全,洪德元.植物分子系统学近五年的研究进展概况[J].植物分类学报,1997.35(5):465~480
[40]Soltis D E, Soltis P S. Molecular data and the dynamic nature of polyploidy[J]. Crit Rev Plant Sci., 1993, 12:243~273
[41]顾红雅.限制性片段长度多态性(RFLPs)在植物系统与进化研究中的应用.见: 陈家宽,杨继主编,植物进化生物学.武汉:武汉大学出版社,1994,209~231
[42]Wang Z-Y, Second G, Tanksley S D, Polymorphism and phylogenetic relationships among species in thegenus Oryza as determined by analysis of nuclear RFLPs[J]. Theor Appl Genet, 1992, 83:565~581
[43]Pillay M Variation of nuclear ribosomal RNA genes in Eragrostis tef(Zucc.) Trotter[J]. Genome, 1997, 40:815~821
[44]Cronn R C,Zhao X,Paterson A H et al. Polymorphism and concerted evolution in a tandemly repeated gene family: 5S ribosomal DNA in diploid and allopolyploid cottons[J]. J Mol Evol, 1996, 42:685~705
[45]Sastri D C, Hilu K, Appels R et al. An overview of evolution in plant 5S rDNA[J]. Plant Syst Evol, 1992, 183:169~181
[46]Second G, Wang Z Y Mitochondrial DNA RFLP in genus Oryza and cultivated rice. Genet Resour Crop Evol, 1992, 39:125~140
[47]陈之端,汪小全,孙海英等.马尾树科的系统位置:来自rbcL基因核苷酸序列的证据[J].植物分类学报,1998,36(1):1~7
[48]Pillay M, Hilu K W Chloroplast DNA restriction site analysis in the genus Bromus(Poaceae)[J]. Amer J Bot, 1995, 83:239~250
[49]Olmstead RG,Paimer J D. Chloroplast DNA systematics:a review of methods and data analysis[J]. Amer J Bot, 1994, 81:1205~1224
[50]Soltis D E, Soltis P S Molecular data and the dynamic nature of polyploidy[J].Crit Rev Plant Sci, 1993.12:243~273
[51]Wolfe K H,Li W2H,Sharp P M,1987. Rates of nucleotide substitution vary greatly among plant mitochondrial, choroplast,and nuclear DNAs. Proc Natl Acad Sci USA, 84:9054~9058
[52]Hsiao C, Chatterton N J, Asay K H. Phylogenetic relationships of 10 grass species: an assessment of phylogenetic utility of the internal transcribed spacer region in nuclear ribosomal DNA in monocots[J]. Genome, 1994, 37:112~120
[53]Hsiao C, Chatterton N J, Asay K H et al.. Phylogenetic relationships of the monogenomic species of the wheat tribe, Triticeae(Poaceae),inferred from nuclear rDNA(ITS) sequences[J]. Genome, 1995a, 38:211~223
[52]Grant V. Plant Speciation[M]. New York:Columbia University Press., 1981, 283~356
[53]Ainouche M L,Bayer R. On the origins of the tetraploid Bromus species(section Bromus, Poaceae): insights from internal transcribed spacer sequences of nuclear ribosomal DNA[J]. Genome,1997, 730~743
[54]Kollipara K P, Singh R J, Hymowitz T Phylogenetic and genomic relationships in the genus Glycine Willd. Based on sequences from the ITS region of nuclear rDNA[J]. Genome,1997, 40:57~68
[55]张文驹,1998.应用rDNA的ITS区探讨多倍体小麦的基因组起源.武汉:武汉大学博士学位论文
[56]Hara, H., 1966. The Flora of Eastern Himalaya. 1st edn. Tokyo: University of Tokyo Press.
[57]Wu C-Y(吴征镒),Lu A-M(路安民),Tang Y-C(汤彦承),Chen Z-D(陈之端)Li D-Z(李德铢)The Families and Genera of Angiosperms in China,a Comprehensive Analysis(中国被子植物科属综论)[M],2003,Beijing:Science Press.164-168.
[58]Zhou Z—Z(周忠泽),Tao H-L(陶汉林),Ban Q(班勤),Xu R-X(许仁鑫),Li Y-C(李玉成)Pollen morphology of Polygonum section Aconogonon Meisn.in China[J].Acta Phytotaxonomica Sinica(植物分类学报),2002,40:110-124.
[59]刘明珍,周忠泽,邱英雄,孙伟.董翔分子证据支持蓝药蓼和大铜钱叶蓼归入冰岛蓼属[J].植物分类学报,2007,45(2):227-233(2007)
[60]Zhou Z-Z(周忠泽),Zhang X-P(张小平),Xu R-X(许仁鑫).2004.Pollen morphology of Koenigia from China.Acta Phytotaxonomica Sinica(植物分类学报)42:513—523.
[61]Hedberg O. 1997. The genus Koenigia L. emend. Hedberg(Polygonaceae). Botanical Journal of the Linnean Society 124: 295-330.
[62]Samuelsson G. 1930. Plantae sinense, a dre. H. Smith annis 1921-1922 lectae. ⅩⅩ. Polygonaceae. Acta Horti Gothoburgenses 5:1-11.
[63]Hong S-P, Hedberg O. 1990. Parallel evolution of aperture numbers and arrangement in the genera Koenigia, Persiearia and Aconogonon(Polygonaceae). Grana 29: 177-184.
[64]Li, H.-L. The genus Tovara(Polygonceae). Rhodora, 1952, 54:19-25
[65] Holm, T., 1927. Polygonum: sectio Tovara. Botanical Gazette, 84: 1-26.
[66] Meissner, C. F., Polygonaceae. In A. de Candolle, Prodromus Systematis naturalis Regni Vegetabilis, 14: Paris
[67] Graham, S. A. & Wood, C. E., 1965. The genera of Polygonaceae in the South Eastern United States. Journal of the Arnold Arboretum, 46:91-121.
[68] Bailey JP, Stace CA. Chromosome number, morphology, pairing and DNA values of species and hybrids in the genus Fallopia (Polygonaceae) [J]. Plant Systematics and Evolution, 1992, 180: 29-52.
[69] Holub, J. Fallopia Adans. 1763 Instead of Bilderdykia Dum. 1827 .Folia Geobotanica e Phytotaxonomica, Praha, 1970,6: 171-177.
[70] Watson, S. On Section Avicularia of the genus Polygonum[J]. American Naturalist,1873,7:662-665.
[71] Greene, E. L., 1904. Certain Polygonaceous Genera. Leaflet Botanical Observation and Criticism, 1: 17-50.
[72] Hickman, J. C, 1984. Nomenclatural changes in Persicaria, Polygonum and Rumex. Madrono, 31: 249-252
[73] Dammer U, Diels L. Beitrage zur Flora des Tsin ling shan und andere Zusatze zur Flora von Central-China[J]. Bot. Jahrb. Syst., 1905, 36, Beibl. 82: 36.
[74] Hong S P. A pollenmorphological re-evalution of Harpagocarpus and Eskemukerjea (Polygoneceae)[J]. Grana, 1988,27:291-295
[75] Chen Q-F. A study of resources of Fagopyrum (Polygonaceae) native to China[J].Botanical Journal of the Linnean Society, 1999,130: 53-64.