The tomato WV gene encoding a thioredoxin protein is essential for chloroplast development at low temperature and high light intensity
The tomato WV gene encoding a thioredoxin protein is essential for chloroplast development at low temperature and high light intensity
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编码硫氧还蛋白蛋白的番茄 WV 基因对于低温和高光强度下叶绿体的发育至关重要
DOI：
10.1186/s12870-019-1829-4
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发表时间：
2019-06-20
影响因子：
5.3
通讯作者：
Ye, Zhibiao
中科院分区：
文献类型：
--
作者：
Gao, Shenghua;Gao, Wenjing;Ye, Zhibiao
背景：叶绿体生物发生是高等植物光自养生长的关键，是一个复杂的过程。白色翠绿（wv）突变体已被用于揭示植物叶绿体发育和叶绿体基因表达调控的分子机制。然而，大多数控制白色翠绿表型的基因仍然未知。结果：在这项研究中，我们鉴定了一个温度和光强敏感突变体，命名为wv。低温强光条件下，wv突变体未成熟叶片叶绿素含量显著降低。透射电镜观察表明，wv突变体幼叶叶绿体缺乏有组织的类囊体膜，而成熟叶叶绿体呈新月形，基质发育良好，颗粒状类囊体堆积。免疫印迹分析表明，在wv突变体中，光合复合物的蛋白质含量显著降低。基于图谱克隆和转基因分析，我们确定wv表型是由wv基因第一个内含子单碱基突变引起的，该内含子编码一个含有365个氨基酸的硫氧还蛋白。qRT-PCR分析显示，WV突变体中WV基因的表达明显下调。此外，通过RNAi敲低WV基因也导致嫩叶呈现白色嫩绿，这表明该突变可能通过抑制WV基因的表达来阻断叶绿体的分化。WV的表达在顶芽中达到峰值，随着发育阶段的增加逐渐降低，这与WV突变体的表型一致。qRT-PCR对叶绿体编码基因的表达分析表明，wv突变影响了叶绿体编码PEP依赖基因的表达模式。结论：wv突变体对低温、光强敏感。WV基因是叶绿体分化所必需的基因。第一个内含子的单碱基突变导致WV基因表达下调，从而抑制叶绿体编码基因的表达，从而阻断叶绿体形成和叶绿素合成。
Background:Chloroplast biogenesis, a complex process in higher plants, is the key to photoautotrophic growth in plants. White virescent (wv) mutants have been used to unfold the molecular mechanisms underlying the regulation of chloroplast development and chloroplast gene expression in plants. However, most of genes controlling white virescent phenotype still remain unknown.Results:In this study, we identified a temperature- and light intensity-sensitive mutant, named as wv. The content of chlorophyll was dramatically decreased in the immature leaves of wv mutant under the conditions of low temperature and high-light intensity. TEM observation showed that the chloroplasts in the young leaves of wv mutant lacked an organized thylakoid membrane, whereas crescent-shaped chloroplasts with well-developed stromal and stacked grana thylakoids in the mature leaves were developed. Immunoblot analyses suggested that proteins of photosynthetic complexes were decreased substantially in wv mutants. Based on map-based cloning and transgenic analysis, we determined that the wv phenotype was caused by single base mutation in the first intron of WV gene, which encoded a thioredoxin protein with 365 amino acids. qRT-PCR analysis revealed that the expression of WV gene was significantly down-regulated in wv mutant. In addition, knockdown of WV gene through RNAi also resulted in white virescent young leaves, suggesting that the mutation possibly blocks the differentiation of chloroplasts through inhibiting the expression of WV gene. Furthermore, the expression of WV peaked in apical buds and gradually decreased along with the developmental stage, which was consistent with the wv mutant phenotype. Expression analysis of chloroplast-encoded genes by qRT-PCR showed that the wv mutation affected the expression pattern of chloroplast-encoded PEP dependent genes.Conclusion:Our results suggested that wv mutant was sensitive to low temperature and light intensity. WV gene was essential for chloroplast differentiation. A single base mutation in the first intron resulted in down-regulation of WV gene expression, which inhibited the expression of chloroplast-encoded genes, thereby blocking chloroplast formation and chlorophyll synthesis.