Leaf Endoplasmic Reticulum Bodies Identified in Arabidopsis Rosette Leaves Are Involved in Defense against Herbivory
Leaf Endoplasmic Reticulum Bodies Identified in Arabidopsis Rosette Leaves Are Involved in Defense against Herbivory
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DOI：
10.1104/pp.18.00984
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发表时间：
2019-04-01
期刊：
影响因子：
7.4
通讯作者：
Shimada, Tomoo
中科院分区：
文献类型：
--
作者：
Nakazaki, Akiko;Yamada, Kenji;Shimada, Tomoo
内质网体是内质网（ER）衍生的细胞器，特异性地存在于昆虫目中，被认为在植物防御昆虫和病原体中起作用。ER体通常分为两种类型：幼苗表皮细胞中的组成型ER体和莲座叶中的伤口诱导型ER体。在此，我们揭示了在拟南芥莲座叶中发现的第三种类型的ER体，并将其命名为“叶ER体”（L-ER体）。L-ER体组成性地发生在莲座叶的特定细胞中：边缘细胞、覆盖中脉的表皮细胞和巨大的铺路细胞。L-ER体的分布与碱性螺旋-环-螺旋转录因子NAI 1的表达谱密切相关，NAI 1负责组成性ER体的形成。在指甲突变体叶片中很少观察到L-ER体，表明NAI 1参与了L-ER体的形成。共聚焦成像分析显示，L-ER体积累了两种类型的β-葡萄糖苷酶：PYK 10，组成型ER体β-葡萄糖苷酶;和BETA-GLUCOSIDASE 18（BGLU 18），创伤诱导型ER体β-葡萄糖苷酶。结合bglu 18 pyk 10突变体中L-ER体的缺失，这些结果表明BGLU 18和PYK 10是L-ER体的主要组分。随后的喂养试验与陆地等足类Armadillidium vulgare发现，bglu 18 pyk 10叶被严重损坏的结果，草食动物。此外，bglu 18 pyk 10突变体在4-甲氧基吲哚-3-基甲基硫代葡萄糖苷的水解中是缺陷的。这些结果表明，L-ER体参与了从4-甲氧基吲哚-3-基甲基硫代葡萄糖苷产生防御化合物，该防御化合物保护拟南芥叶片免受草食动物的攻击。
ER bodies are endoplasmic reticulum (ER)-derived organelles specific to the order Brassicales and are thought to function in plant defense against insects and pathogens. ER bodies are generally classified into two types: constitutive ER bodies in the epidermal cells of seedlings, and wound-inducible ER bodies in rosette leaves. Herein, we reveal a third type of ER body found in Arabidopsis (Arabidopsis thaliana) rosette leaves and designate them "leaf ERbodies" (L-ER bodies). L-ER bodies constitutively occurred in specific cells of the rosette leaves: marginal cells, epidermal cells covering the midrib, and giant pavement cells. The distribution of L-ER bodies was closely associated with the expression profile of the basic helix-loop-helix transcription factor NAI1, which is responsible for constitutive ER-body formation. L-ER bodies were seldom observed in nail mutant leaves, indicating that NAI1 is involved in L-ER body formation. Confocal imaging analysis revealed that L-ER bodies accumulated two types of beta-glucosidases: PYK10, the constitutive ER-body beta-glucosidase; and BETA-GLUCOSIDASE18 (BGLU18), the wound-inducible ER-body beta-glucosidase. Combined with the absence of L-ER bodies in the bglu18 pyk10 mutant, these results indicate that BGLU18 and PYK10 are the major components of L-ER bodies. A subsequent feeding assay with the terrestrial isopod Armadillidium vulgare revealed that bglu18 pyk10 leaves were severely damaged as a result of herbivory. In addition, the bglu18 pyk10 mutant was defective in the hydrolysis of 4-methoxyindol-3-ylmethyl glucosinolate These results suggest that L-ER bodies are involved in the production of defensive compound(s) from 4-methoxyindol-3-ylmethyl glucosinolate that protect Arabidopsis leaves against herbivory attack.