Identification and characterization of tomato gibberellin 2-oxidases (GA2oxs) and effects of fruit-specific SlGA2ox1 overexpression on fruit and seed growth and development
Identification and characterization of tomato gibberellin 2-oxidases (GA2oxs) and effects of fruit-specific SlGA2ox1 overexpression on fruit and seed growth and development
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DOI：
10.1038/hortres.2016.59
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发表时间：
2016-12-07
影响因子：
8.7
通讯作者：
Li, Yi
中科院分区：
文献类型：
--
作者：
Chen, Shen;Wang, Xiaojing;Li, Yi
赤霉素（GAs）在番茄果实的生长发育中起着重要作用。以前发表的研究集中在GA对番茄果实的影响上，在整个植物中使用化学处理、GA生物合成和分解代谢基因的组成型过表达或沉默。而GA分解代谢酶基因GA 2-oxidases（GA 2 oxs）的果实特异性过表达则为研究内源GA在果实发育中的作用提供了一种新的途径。在这项研究中，我们已经确定了11 SlGA 2 ox蛋白在番茄，分为三个亚组。基序分析和多重序列比对表明，除了SlGA 2 ox 10之外，所有的SlGA 2 oxs都具有相似的基序组成和高度的序列保守性。定量逆转录-PCR分析表明，SlGA 2 oxs在番茄果实不同发育阶段表现出差异表达模式。当果实特异性启动子TFM 7用于控制SlGA 2 ox 1的表达时，我们观察到营养器官的生长和发育没有变化。但对单果重、种子数和发芽率有显著影响。我们还用GA生物合成抑制剂处理番茄果实，观察到与转基因果实相似的表型。此外，我们已经证明，在转基因番茄果实中细胞扩增和GA响应基因的表达下调，支持SlGA 2 ox 1的过表达导致内源性GA的减少。本研究进一步证明了内源GAs和SlGA 2 ox 1基因在番茄果实重量、种子发育和萌发中起着重要的调控作用。
Gibberellins (GAs) play a crucial role in growth and development of the tomato fruit. Previously published studies focusing on the effect of GAs on tomato fruits used chemical treatments, constitutive overexpression or silencing of GA biosynthetic and catabolic genes globally throughout the plant. Fruit-specific overexpression of GA catabolic enzyme genes GA2-oxidases (GA2oxs), however, may provide an alternative method to study the role of endogenous GAs on the fruit development. In this study, we have identified 11 SlGA2ox proteins in tomato that are classified into three subgroups. Motif analysis and multiple sequence alignments have demonstrated that all SlGA2oxs, except SlGA2ox10, have similar motif compositions and high-sequence conservation. Quantitative reverse transcription-PCR analysis has showed that SlGA2oxs exhibit differential expression patterns in tomato fruits at different developmental stages. When the fruit-specific promoter TFM7 was used to control the expression of SlGA2ox1, we observed no changes in growth and development of vegetative organs. However, fruit weight, seed number and germination rate were significantly affected. We also treated tomato fruits with GA biosynthesis inhibitor and observed phenotypes similar to those of the transgenic fruits. Furthermore, we have demonstrated that expression of cell expansion and GA responsive genes were downregulated in transgenic tomato fruits, supporting that overexpression of the SlGA2ox1 leads to reduction in endogenous GAs. This study provides additional evidence that endogenous GAs and the SlGA2ox1 gene play an important role in controlling on fruit weight, seed development and germination in tomato plant.