Allelic Variation in the Chloroplast Division Gene FtsZ2-2 Leads to Natural Variation in Chloroplast Size
Allelic Variation in the Chloroplast Division Gene FtsZ2-2 Leads to Natural Variation in Chloroplast Size
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DOI：
10.1104/pp.19.00841
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发表时间：
2019-11-01
期刊：
影响因子：
7.4
通讯作者：
Osteryoung, Katherine W.
中科院分区：
文献类型：
--
作者：
Kadirjan-Kalbach, Deena K.;Turmo, Aiko;Osteryoung, Katherine W.
叶绿体的大小在自然界中有很大的差异，但其潜在的机制尚不清楚。通过利用拟南芥与拟南芥杂交获得的近等基因系群体，（拟南芥）加入佛得角群岛（Cvi-1），其具有较大的叶绿体，和兰茨贝格直立（Ler-0），具有较小的叶绿体，我们确定Cvi-1中的大叶绿体表型与编码叶绿体分裂蛋白FtsZ 2 -2的基因中的等位基因变异相关，叶绿体内收缩FtsZ环的微管蛋白相关细胞骨架成分。测序结果表明，Cvi-1 FtsZ 2 -2等位基因编码的C-末端截短的蛋白质缺乏一个区域所需的FtsZ 2 -2与内包膜蛋白的相互作用，和功能互补实验中的哥伦比亚-0 ftsZ 2 -2无效突变体证实该等位基因的原因增加叶绿体的大小在Cvi-1。在1001基因组数据库中的FtsZ 2 -2编码序列的比较表明，Cvi-1等位基因是罕见的，并确定了额外的罕见的功能丧失等位基因，包括一个自然的无效等位基因，在其他三个加入，所有这些都有扩大的叶绿体表型。FtsZ 2 -2基因中的非同义替换与同义替换的比率高于拟南芥中的FtsZ家族的另外两个成员FtsZ 2 -1（FtsZ 2 -2的近缘同源物）和功能不同的FtsZ 1 -1，表明FtsZ 2 -2编码序列上的约束比FtsZ 2 -1或FtsZ 1 -1更宽松。我们的研究结果表明，FtsZ 2 -2的等位基因变异有助于拟南芥叶绿体大小的自然变异，他们还表明，拟南芥的自然变异可以用来破译基本细胞生物学性状，如细胞器大小的差异的遗传基础。
Chloroplast size varies considerably in nature, but the underlying mechanisms are unknown. By exploiting a near-isogenic line population derived from a cross between the Arabidopsis (Arabidopsis thaliana) accessions Cape Verde Islands (Cvi-1), which has larger chloroplasts, and Landsberg erecta (Ler-0), with smaller chloroplasts, we determined that the large-chloroplast phenotype in Cvi-1 is associated with allelic variation in the gene encoding the chloroplast-division protein FtsZ2-2, a tubulin-related cytoskeletal component of the contractile FtsZ ring inside chloroplasts. Sequencing revealed that the Cvi-1 FtsZ2-2 allele encodes a C-terminally truncated protein lacking a region required for FtsZ2-2 interaction with inner-envelope proteins, and functional complementation experiments in a Columbia-0 ftsZ2-2 null mutant confirmed this allele as causal for the increased chloroplast size in Cvi-1. Comparison of FtsZ2-2 coding sequences in the 1001 Genomes database showed that the Cvi-1 allele is rare and identified additional rare loss-of-function alleles, including a natural null allele, in three other accessions, all of which had enlarged-chloroplast phenotypes. The ratio of nonsynonymous to synonymous substitutions was higher among the FtsZ2-2 genes than among the two other FtsZ family members in Arabidopsis, FtsZ2-1, a close paralog of FtsZ2-2, and the functionally distinct FtsZ1-1, indicating more relaxed constraint on the FtsZ2-2 coding sequence than on those of FtsZ2-1 or FtsZ1-1. Our results establish that allelic variation in FtsZ2-2 contributes to natural variation in chloroplast size in Arabidopsis, and they also demonstrate that natural variation in Arabidopsis can be used to decipher the genetic basis of differences in fundamental cell biological traits, such as organelle size.