Genetic Interactions Reveal that Specific Defects of Chloroplast Translation are Associated with the Suppression of var2-Mediated Leaf Variegation
Genetic Interactions Reveal that Specific Defects of Chloroplast Translation are Associated with the Suppression of var2-Mediated Leaf Variegation
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遗传相互作用揭示叶绿体翻译的特定缺陷与 var2 介导的叶片杂色的抑制有关
DOI：
10.1111/jipb.12078
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发表时间：
2013-10-01
影响因子：
11.4
通讯作者：
Yu, Fei
中科院分区：
文献类型：
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作者：
Liu, Xiayan;Zheng, Mengdi;Yu, Fei
拟南芥黄色杂色 (var2) 突变体在叶绿体 FtsH 家族金属蛋白酶 AtFtsH2/VAR2 中存在缺陷，并显示出有趣的绿色和白色叶子杂色。这种独特的 var2 介导的叶片杂色为剖析叶绿体发育的遗传调控提供了一种简单而强大的工具。在这里，我们报告了一种新的 var2 抑制基因 SUPPRESSOR OF VARIEGATION8 (SVR8) 的分离和表征，该基因编码假定的叶绿体核糖体大亚基蛋白 L24。 SVR8 的突变抑制了 var2 在环境温度下的叶片杂色，并部分抑制了 var2 的寒冷诱导的失绿表型。 SVR8 的缺失会导致独特的叶绿体 rRNA 加工缺陷，特别是 23S-4.5S 双顺反子前体。 svr8 23S-4.5S前体中主要异常加工位点的恢复表明它与SVR8/L24在核糖体上结合的位置并不相同。令人惊讶的是，我们发现叶绿体核糖体小亚基蛋白 S21 的丢失会导致叶绿体 rRNA 加工异常，但不会抑制 var2 杂色。这些发现表明，叶绿体翻译的特定方面的破坏，而不是叶绿体翻译的普遍损害，抑制了 var2 杂色和叶绿体发育中复杂遗传相互作用的存在。
Arabidopsis thaliana L. yellow variegated (var2) mutant is defective in a chloroplast FtsH family metalloprotease, AtFtsH2/VAR2, and displays an intriguing green and white leaf variegation. This unique var2-mediated leaf variegation offers a simple yet powerful tool for dissecting the genetic regulation of chloroplast development. Here, we report the isolation and characterization of a new var2 suppressor gene, SUPPRESSOR OF VARIEGATION8 (SVR8), which encodes a putative chloroplast ribosomal large subunit protein, L24. Mutations in SVR8 suppress var2 leaf variegation at ambient temperature and partially suppress the cold-induced chlorosis phenotype of var2. Loss of SVR8 causes unique chloroplast rRNA processing defects, particularly the 23S-4.5S dicistronic precursor. The recovery of the major abnormal processing site in svr8 23S-4.5S precursor indicate that it does not lie in the same position where SVR8/L24 binds on the ribosome. Surprisingly, we found that the loss of a chloroplast ribosomal small subunit protein, S21, results in aberrant chloroplast rRNA processing but not suppression of var2 variegation. These findings suggest that the disruption of specific aspects of chloroplast translation, rather than a general impairment in chloroplast translation, suppress var2 variegation and the existence of complex genetic interactions in chloroplast development.