Conjugating algae perform characteristic sexual reproduction through conjugation by gametes without flagella. These algae sexually reproduce through the formation of zygospores from single clones (homothallic) and through the formation of zygospores between different clones (heterothallic). The conjugating algae genus Spirogyra is generally found in freshwater environments, and its conjugation process has been well investigated. However, due to experimental difficulties in inducing conjugation, heterothallism has not been described in Spirogyra. Herein, we reported, to the best of our knowledge, the first discovery of heterothallic Spirogyra strains following the induction of conjugation. The conjugation of the strains of Spirogyra fluviatilis required two clearly genetically differentiated strains. Our mating experiments with these strains also demonstrated that their sexuality was genetically determined and that the F1 strain from germinated zygospores conjugated with only one parental strain. Moreover, phylogenetic analyses showed that these heterothallic strains were phylogenetically related to their homothallic relatives. In this study conducted on Spirogyra, the induction of conjugation in heterothallic strains facilitated our understanding of their diversity.

中文翻译：

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有性生殖的诱导揭示了异源螺旋藻菌株（Zygnematophyceae，Streptophyta）的存在

结合藻类通过没有鞭毛的配子结合进行特征性的有性繁殖。这些藻类通过从单个克隆（同型）形成接合孢子以及通过在不同克隆之间形成接合孢子（异型）进行有性繁殖。共轭藻属 Spirogyra 通常在淡水环境中发现，其共轭过程已得到很好的研究。然而，由于在诱导结合方面的实验困难，在 Spirogyra 中没有描述异体。在本文中，据我们所知，我们首次发现了诱导缀合后的异源水绵菌株。Spirogyra fluviatilis 菌株的结合需要两个明显遗传分化的菌株。我们与这些菌株的交配实验还表明，它们的性是由遗传决定的，并且来自发芽接合孢子的 F1 菌株仅与一个亲本菌株结合。此外，系统发育分析表明，这些异源菌株在系统发育上与其同源亲属相关。在对 Spirogyra 进行的这项研究中，异源菌株中的结合诱导促进了我们对其多样性的理解。