Sexual processesand phylogenetic relationships of a homothallic strain in the Closterium peracerosum-strigosum-littorale complex(Zygnematales, Charophyceae)
Sexual processesand phylogenetic relationships of a homothallic strain in the Closterium peracerosum-strigosum-littorale complex(Zygnematales, Charophyceae)
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Closterium peracerosum-strigosum-littorale 复合体中同宗菌株的性过程和系统发育关系（Zygnematales，Charophyceae）
DOI：
10.1111/j.1529-8817.2010.00806.x
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
H
中科院分区：
文献类型：
--
作者：
Tsuchikane;Y.;Sato;M.;Ootaki;T.,Kokubun;Y.;Nozaki;H.;Ito;M. &Sekimoto;H
Pacerosum-strigosum-littorale(C.PSL.)复合体是单细胞轮藻，有两种接合孢子形成方式，异亲和同亲和。从日本稻田中分离到一株同源新月浑菌(Closterium)(命名为KoDama20)。根据1506组I内含子的比对，中断核SSU rDNA的同源科达马20与异性交配基团II-B关系最近，后者部分有性分离于II-A组。对科达马20接合过程的延时摄影显示，大多数观察到的合孢子来自一个营养细胞。有性交配过程包括五个阶段：(1)细胞分裂，由一个营养细胞形成两个姐妹配子囊细胞；(2)姐妹配子囊细胞之间(或另一个相邻个体的配子囊细胞之间)形成有性对；(3)形成接合乳突；(4)从配子对的两个成员中释放配子原生质体；(5)通过原生质体融合形成合子孢子。接合培养过程中，细胞密度和光照条件是至关重要的。我们提出了结合促进因子的存在。
Members of theClosterium peracerosum–strigosum–littorale(C. psl.) complex are unicellular charophycean algae in which there are two modes of zygospore formation, heterothallic and homothallic. A homothallic strain ofClosterium(designation, kodama20) was isolated from a Japanese rice paddy field. Based on alignment of the 1506 group‐I introns, which interrupt nuclear SSU rDNAs, homothallic kodama20 is most closely related to the heterothallic mating group II‐B, which is partially sexually isolated from group II‐A. Time‐lapse photography of the conjugation process in kodama20 revealed that most of the observed zygospores originated from one vegetative cell. The sexual conjugation process consisted of five stages: (1) cell division resulting in the formation of two sister gametangial cells from one vegetative cell, (2) formation of a sexual pair between the two sister gametangial cells (or between gametangial cells of another adjoined individual), (3) formation of conjugation papillae, (4) release of gametic protoplasts from both members of a pair, and (5) formation of the zygospore by protoplast fusion. For conjugation to progress, the cell density and light condition in the culture was critical. We suggested the presence of a conjugation promotion factor.