Based on the morphology of gametes, sexual reproduction in brown algae is usually classified into three types: isogamy, anisogamy, and oogamy. In isogamy, chloroplasts and chloroplast DNA (chlDNA) in the sporophyte cells are inherited biparentally, while mitochondria (or mitochondrial DNA, mtDNA) is inherited maternally. In oogamy, chloroplasts and mitochondria are inherited maternally. However, the patterns of mitochondrial and chloroplast inheritance in anisogamy have not been clarified. Here, we examined derivation of mtDNA and chlDNA in the zygotes through strain-specific PCR analysis using primers based on single nucleotide polymorphism in the anisogamous brown alga Mutimo cylindricus . In 20-day-old sporophytes after fertilization, mtDNA and chlDNA derived from female gametes were detected, thus confirming the maternal inheritance of both organelles. Additionally, the behavior of mitochondria and chloroplasts in the zygotes was analyzed by examining the consecutive serial sections using transmission electron microscopy. Male mitochondria were isolated or compartmentalized by a double-membrane and then completely digested into a multivesicular structure 2 h after fertilization. Meanwhile, male chloroplasts with eyespots were observed even in 4-day-old, seven-celled sporophytes. The final fate of male chloroplasts could not be traced. Organelle DNA copy number was also examined in female and male gametes. The DNA copy number per chloroplast and mitochondria in male gametes was lower compared with female organelles. The degree of difference is bigger in mtDNA. Thus, changes in different morphology and DNA amount indicate that maternal inheritance of mitochondria and chloroplasts in this species may be based on different processes and timing after fertilization.

中文翻译：

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异配子褐藻 Mutimo cylindricus (Phaeophyceae) 线粒体和叶绿体的细胞质遗传

根据配子的形态，褐藻的有性繁殖通常分为三类：同卵、异卵和卵子。在同种配偶体中，孢子体细胞中的叶绿体和叶绿体 DNA (chlDNA) 是双亲遗传的，而线粒体（或线粒体 DNA，mtDNA）是母系遗传的。在卵子生殖中，叶绿体和线粒体是母系遗传的。然而，异配性中线粒体和叶绿体遗传的模式尚未阐明。在这里，我们使用基于异配子褐藻 Mutimo cylindricus 中单核苷酸多态性的引物，通过菌株特异性 PCR 分析检查了受精卵中 mtDNA 和 chlDNA 的来源。在受精后20天龄的孢子体中，检测到来自雌配子的mtDNA和chlDNA，从而证实了两种细胞器的母系遗传。此外，通过使用透射电子显微镜检查连续的连续切片来分析受精卵中线粒体和叶绿体的行为。雄性线粒体通过双膜分离或分隔，然后在受精后 2 小时完全消化成多泡结构。同时，即使在 4 天大的七细胞孢子体中也观察到带有眼斑的雄性叶绿体。无法追踪雄性叶绿体的最终命运。还在雌性和雄性配子中检查了细胞器 DNA 拷贝数。与雌性细胞器相比，雄性配子中每个叶绿体和线粒体的 DNA 拷贝数较低。mtDNA 的差异程度更大。因此，