Arabidopsis PARC6 Is Critical for Plastid Morphogenesis in Pavement, Trichome, and Guard Cells in Leaf Epidermis
Arabidopsis PARC6 Is Critical for Plastid Morphogenesis in Pavement, Trichome, and Guard Cells in Leaf Epidermis
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DOI：
10.3389/fpls.2019.01665
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发表时间：
2020-01
影响因子：
5.6
通讯作者：
Hiroki Ishikawa;Mana Yasuzawa;Nana Koike;Alvin Sanjaya;Shota Moriyama;Aya Nishizawa;Kanae Matsuoka;Shun-ichi Sasaki;Y. Kazama;Y. Hayashi;T. Abe;M. Fujiwara;R. Itoh
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文献类型：
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作者：
Hiroki Ishikawa;Mana Yasuzawa;Nana Koike;Alvin Sanjaya;Shota Moriyama;Aya Nishizawa;Kanae Matsuoka;Shun-ichi Sasaki;Y. Kazama;Y. Hayashi;T. Abe;M. Fujiwara;R. Itoh
最近，一个隐性拟南芥突变体的叶表皮铺装细胞丰富的小座进行了视觉筛选和分离。该突变体表型的基因被确定为PARC 6，叶绿体分裂位点调节基因。突变等位基因parc 6 -5在编码序列的N端和C端分别携带两个点突变（G62 R和W700 stop）。在这里，我们进一步的特点parc 6 -5和其他parc 6突变等位基因，并表明，PARC 6在质体形态发生中起着关键作用，在所有类型的细胞的叶表皮：铺路细胞，毛状体细胞，保卫细胞。PARC 6转运肽（TP）与绿色荧光蛋白（GFP）的融合蛋白在植物细胞中的瞬时表达表明，G62 R突变对PARC 6 N-末端区域的TP活性没有影响或影响很小。然后，借助于基质靶向荧光蛋白，在显微镜下分析野生型（WT）和parc 6突变体（parc 6 -1、parc 6 -3、parc 6 -4和parc 6 -5）的叶表皮中的质体形态。在parc 6铺面细胞，质体往往承担异常的葡萄状形态，类似于严重的质体分裂突变体，atminE 1，arc 6。在parc 6毛状体细胞中，质体表现出极端的葡萄状聚集，没有产生巨大的质体（直径>6 µm），作为一般表型。在parc 6保卫细胞中，质体表现出各种异常表型，包括数量减少，体积增大，和激活的基质，类似于atminE 1和arc 6保卫细胞。然而，与atminE 1和arc 6不同，parc 6表现出少量的微型叶绿体（直径< 2 µm），很少产生叶绿体缺陷的保卫细胞。重要的是，与parc 6不同，叶绿体分裂位点突变体arc 11在毛状体和保卫细胞中表现出WT样质体表型。最后，对表达功能性PARC 6-GFP蛋白的parc 6互补系的观察表明，PARC 6-GFP在收缩和非收缩叶绿体中形成环状结构，并且PARC 6在叶绿体分裂过程中动态地改变其构型。
Recently, a recessive Arabidopsis thaliana mutant with abundant stromules in leaf epidermal pavement cells was visually screened and isolated. The gene responsible for this mutant phenotype was identified as PARC6, a chloroplast division site regulator gene. The mutant allele parc6-5 carried two point mutations (G62R and W700stop) at the N- and C-terminal ends of the coding sequence, respectively. Here, we further characterized parc6-5 and other parc6 mutant alleles, and showed that PARC6 plays a critical role in plastid morphogenesis in all cell types of the leaf epidermis: pavement cells, trichome cells, and guard cells. Transient expression of PARC6 transit peptide (TP) fused to the green fluorescent protein (GFP) in plant cells showed that the G62R mutation has no or little effect on the TP activity of the PARC6 N-terminal region. Then, plastid morphology was microscopically analyzed in the leaf epidermis of wild-type (WT) and parc6 mutants (parc6-1, parc6-3, parc6-4 and parc6-5) with the aid of stroma-targeted fluorescent proteins. In parc6 pavement cells, plastids often assumed aberrant grape-like morphology, similar to those in severe plastid division mutants, atminE1, and arc6. In parc6 trichome cells, plastids exhibited extreme grape-like aggregations, without the production of giant plastids (>6 µm diameter), as a general phenotype. In parc6 guard cells, plastids exhibited a variety of abnormal phenotypes, including reduced number, enlarged size, and activated stromules, similar to those in atminE1 and arc6 guard cells. Nevertheless, unlike atminE1 and arc6, parc6 exhibited a low number of mini-chloroplasts (< 2 µm diameter) and rarely produced chloroplast-deficient guard cells. Importantly, unlike parc6, the chloroplast division site mutant arc11 exhibited WT-like plastid phenotypes in trichome and guard cells. Finally, observation of parc6 complementation lines expressing a functional PARC6-GFP protein indicated that PARC6-GFP formed a ring-like structure in both constricting and non-constricting chloroplasts, and that PARC6 dynamically changes its configuration during the process of chloroplast division.