BEL1-LIKE HOMEODOMAIN 11 regulates chloroplast development and chlorophyll synthesis in tomato fruit
BEL1-LIKE HOMEODOMAIN 11 regulates chloroplast development and chlorophyll synthesis in tomato fruit
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BEL1-LIKE HOMEODOMAIN 11 调节番茄果实中的叶绿体发育和叶绿素合成
DOI：
10.1111/tpj.13924
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发表时间：
2018-06-01
期刊：
影响因子：
7.2
通讯作者：
Fu, Da-Qi
中科院分区：
文献类型：
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作者：
Meng, Lanhuan;Fan, Zhongqi;Fu, Da-Qi
未成熟番茄的叶绿体发育和叶绿素（Chl）代谢对果实的生长和品质有重要作用，但其机制尚不清楚。在这项研究中，我们初步调查了7个同源框含有转录因子（TF）与特定的成熟相关的表达模式，使用病毒诱导的基因沉默（VIGS）技术，并发现，抑制这些TF之一，BEL 1-LIKE HOMEODOMAIN 11（SLBEL 11）的表达，显着增加未成熟的番茄果实中的叶绿素水平。通过产生稳定的RNA干扰（RNAi）转基因系进一步验证了这种增强的Chl积累。对成熟绿色（MG）期的RNAi-SIBEL 11果实进行RNA测序（RNA-seq），结果表明，与野生型（WT）果实相比，参与叶绿素合成、光合作用和叶绿体发育的48个基因显著上调。基因组全序列同源框TF结合位点扫描结合RNA-seq差异基因表达分析显示，这48个基因中有22个是SlBEL 11蛋白的潜在靶基因。这些基因包括编码原叶绿素还原酶（POR）、镁螯合酶H亚基（CHLH）和叶绿素a加氧酶（CAO）的Chl生物合成相关基因，以及编码叶绿素a/B结合蛋白（CA B）、同源框蛋白knotted 2（TKN 2）和拟南芥假反应调节因子2-LIKE（APRR 2-like）的叶绿体发育相关基因。采用电泳迁移率变动分析（EMSA）和染色质免疫沉淀定量聚合酶链反应（ChIP-qPCR）分析来验证SlBEL 11蛋白可以与TKN 2、CAB和POR的启动子结合。综上所述，我们的研究结果表明，SlBEL 11在番茄果实叶绿体发育和叶绿素合成中起着重要作用。
Chloroplast development and chlorophyll(Chl) metabolism in unripe tomato contribute to the growth and quality of the fruit, however these mechanisms are poorly understood. In this study, we initially investigated seven homeobox-containing transcription factors (TFs) with specific ripening-associated expression patterns using virus-induced gene silencing (VIGS) technology and found that inhibiting the expression of one of these TFs, BEL1-LIKE HOMEODOMAIN11 (SlBEL11), significantly increased Chl levels in unripe tomato fruit. This enhanced Chl accumulation was further validated by generating stable RNA interference (RNAi) transgenic lines. RNA sequencing (RNA-seq) of RNAi-SlBEL11 fruit at the mature green (MG) stage showed that 48 genes involved in Chl biosynthesis, photosynthesis and chloroplast development were significantly upregulated compared with the wild type (WT) fruit. Genomic global scanning for Homeobox TF binding sites combined with RNA-seq differential gene expression analysis showed that 22 of these 48 genes were potential target genes of SlBEL11 protein. These genes included Chl biosynthesis-related genes encoding for protochlorophyllide reductase (POR), magnesium chelatase H subunit (CHLH) and chlorophyllide a oxygenase (CAO), and chloroplast development-related genes encoding for chlorophyll a/b binding protein (CAB), homeobox protein knotted 2 (TKN2) and ARABIDOPSIS PSEUDO RESPONSE REGULATOR 2-LIKE (APRR2-like). Electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation quantitative polymerase chain reaction (PCR) (ChIP-qPCR) assays were employed to verify that SlBEL11 protein could bind to the promoters for TKN2, CAB and POR. Taken together, our findings demonstrated that SlBEL11 plays an important role in chloroplast development and Chl synthesis in tomato fruit.