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Early evolution and phylogeny of Phaeophyceae deduced from the cell fine structure, photosynthetic pigments and molecular phylogeny.

从细胞精细结构、光合色素和分子系统发育推断褐藻纲的早期进化和系统发育。

基本信息

批准号：
15370039
负责人：
KAWAI Hiroshi
金额：
$ 8.26万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Vegetative cells of Giraudyopsis stellifera (Chrysomeridales) have cell wall-like structures composed of mucilaginous substances, and form one or two swarmer(s) when fertile. The swarmers are pear-shaped, provided with a chloroplast having an eyespot and heterokont lateral flagella ; the posterior flagellum shows green fluorescence. After settlement to the substratum, the swarmer first develops into prostrate filaments which then produce erect filaments. The chloroplasts are of typical chromophyte-type having triple-layered thylakoids enclosed in a girdle lamella, and a pyrenoid embedded in the chloroplast. Presence of chlorophylls a,c, fucoxanthin, violaxanthin and diatoxanthin were shown as major photosynthetic pigments by HPLC analyses. Systematic position of Chrysomeridales including Giraudyopsis in higher rank is unclear, but the molecular phylogenetic analyses using rbcL gene sequences revealed that the species is phylogenetically close to Xanthophyceae, Phaeophyceae, Schizocladi … More ophyceae and Phaeothamniophyceae, but was not included in them, and formed clade with Tetrasporopsis (incertae cedis).A molecular phylogenetic analysis of the brown alga Discosporangium mesarthrocarpum using rbcL and 18S rDNA sequences revealed that the species forms a monophyletic clade with Choristocarpus tenellus that is sister to all other brown algae. Although D.mesarthrocarpum has unique disc-shaped plurilocular reproductive organs, D.mesarthrocarpum and C.tenellus share the following basic morphological features which are considered to be plesiomorphic characters in the brown algae : 1) Apical (and diffuse) growth ; 2) Uniseriate, subdichotomously branched filaments ; 3) Multiple chloroplasts per cell without pyrenoids ; 4) Lack of heterotrichy and phaeophycean hairs. The rbcL DNA sequence of an Australian D.mesarthrocarpum specimen showed considerable deviation from Mediterranean and Macaronesian specimens. Therefore, the presence of a second species in the genus is suggested, however, the taxonomic treatment of this putative species is suspended in the present report. Regarding the higher rank systematic position of D.mesarthrocarpum, reappraisal of Discosporangiaceae and Discosporangiales is proposed. Less

金鱼目的营养细胞具有由粘性物质组成的细胞壁状结构，并在受精时形成一到两个成群的个体(S)。虫体呈梨形，叶绿体有眼点和异形体的侧鞭毛，后鞭毛呈绿色荧光。在附着在底物上后，蜘蛛首先发育成俯卧的丝状物，然后产生直立的丝状物。叶绿体为典型的色藻类型，叶绿体内有带状片层包裹的三层类囊体体，叶绿体内嵌有一个蛋白核。高效液相色谱分析表明，叶绿素a、c、岩藻黄质、紫黄质和双藻黄质是主要的光合色素。根据rbcL基因序列进行的分子系统发育分析表明，该种在系统发育上与黄藻科、棕榈科、裂枝菌科(Schizocladi…)相近。利用rbcL和18S rDNA序列对中关节双孢子藻进行了分子系统发育分析，结果表明该种与细小球藻(Choristcarpus Tenellus)形成了一个单系分支，与其他褐藻为姊妹种。虽然中节藻具有独特的圆盘状多眼生殖器官，但中节藻和柔嫩螺旋藻的基本形态特征被认为是褐藻的多形性特征：1)顶端(和弥漫)生长；2)单列、近二叉的分枝花丝；3)每个细胞有多个叶绿体，不含类果核；4)缺乏异毛和叶柄毛。一份澳大利亚石斑鱼标本的rbcL DNA序列显示出与地中海和马卡龙标本的相当大的偏差。因此，提出了该属第二种的存在，然而，本报告暂停了对这一推定种的分类处理。针对中孢子囊菌的较高系统地位，提出了对球孢子菌科和球孢子菌目的重新评价。较少