Marchantia polymorpha, a New Model Plant for Autophagy Studies
Marchantia polymorpha, a New Model Plant for Autophagy Studies
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DOI：
10.3389/fpls.2019.00935
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发表时间：
2019-07-17
影响因子：
5.6
通讯作者：
Ueda, Takashi
中科院分区：
文献类型：
--
作者：
Norizuki, Takuya;Kanazawa, Takehiko;Ueda, Takashi
自噬是细胞质组分在液泡/溶酶体中大量和选择性降解的分解代谢过程。在酿酒酵母中，ATG基因被鉴定为自噬的必需基因，并且大多数ATG基因在包括植物在内的真核生物中高度保守。尽管反向遗传分析揭示了自噬参与陆生植物对非生物和生物胁迫的应答，但对其分子机制的认识仍然有限。这一限制部分是因为在广泛使用的模式植物如拟南芥中，一些ATG基因（包括ATG 8）的增殖，这增加了功能研究的复杂性。此外，由于有限的信息的组成和功能的ATG基因在基地植物和轮藻，它仍然不清楚是否与这些基因的neofunctionalization的ATG基因的倍增。为了深入了解ATG基因在植物进化过程中的多样化，我们比较了ATG基因在植物中的组成，特别关注苔类和轮藻，这是以前没有分析过的。结果表明，地钱、轮藻Klebsormidium nitens和Chara braunii具有基本的ATG基因组，与地钱相比，ATG基因组的冗余度较低。thaliana和藓类小立碗藓（Physcomitrella patens）的基因，表明ATG基因在陆生植物进化过程中发生了增殖。我们还试图建立一个分析自噬的实验系统。多形。我们构建了表达荧光标记的MpATG 8的转基因植物，观察其在M.在多形藻中，使用CRISPR/Cas9系统通过基因组编辑产生自噬缺陷突变体。这些工具使我们能够证明MpATG 8以MpATG 2-、MpATG 5-和MpATG 7-依赖的方式被转运到液泡中，这表明荧光标记的MpATG 8可以用作M.多形。M. polymorpha为研究植物自噬的机制和进化提供了一个强有力的系统。
Autophagy is a catabolic process for bulk and selective degradation of cytoplasmic components in the vacuole/lysosome. In Saccharomyces cerevisiae, ATG genes were identified as essential genes for autophagy, and most ATG genes are highly conserved among eukaryotes, including plants. Although reverse genetic analyses have revealed that autophagy is involved in responses to abiotic and biotic stresses in land plants, our knowledge of its molecular mechanism remains limited. This limitation is partly because of the multiplication of some ATG genes, including ATG8, in widely used model plants such as Arabidopsis thaliana, which adds complexity to functional studies. Furthermore, due to limited information on the composition and functions of the ATG genes in basal land plants and charophytes, it remains unclear whether multiplication of ATG genes is associated with neofunctionalization of these genes. To gain insight into the diversification of ATG genes during plant evolution, we compared the composition of ATG genes in plants with a special focus on a liverwort and two charophytes, which have not previously been analyzed. Our results showed that the liverwort Marchantia polymorpha and the charophytes Klebsormidium nitens and Chara braunii harbor fundamental sets of ATG genes with low redundancy compared with those of A. thaliana and the moss Physcomitrella patens, suggesting that multiplication of ATG genes occurred during land plant evolution. We also attempted to establish an experimental system for analyzing autophagy in M. polymorpha. We generated transgenic plants expressing fluorescently tagged MpATG8 to observe its dynamics in M. polymorpha and produced autophagy-defective mutants by genome editing using the CRISPR/Cas9 system. These tools allowed us to demonstrate that MpATG8 is transported into the vacuole in an MpATG2-, MpATG5-, and MpATG7-dependent manner, suggesting that fluorescently tagged MpATG8 can be used as an autophagosome marker in M. polymorpha. M. polymorpha can provide a powerful system for studying the mechanisms and evolution of autophagy in plants.