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Article|07 Dec 2016|OPEN
Identification and characterization of tomato gibberellin 2-oxidases (GA2oxs) and effects of fruit-specific SlGA2ox1 overexpression on fruit and seed growth and development
Shen Chen1 , Xiaojing Wang1 , Liying Zhang2 , Shanshan Lin1 , Decai Liu1 , Quanzhi Wang3,4 , Shanya Cai3 , Rania El-Tanbouly5 , Lijun Gan2 and Han Wu1 , , Yi Li,1,5 ,
1State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing 210095, China
2College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
3Jiangsu Polytechnic College of Agriculture and Forestry, Zhenjiang 212400, China
4Jiangsu Engineering and Technology Center for Modern Horticulture, Zhenjiang 212400, China
5Department of Plant Science and Landscape Architecture, University of Connecticut, Storrs, CT 06269, USA
*Corresponding author. E-mail: wuhan@njau.edu.cn,yi.li@uconn.edu

Horticulture Research 3,
Article number: 59 (2016)
doi: https://doi.org/10.1038/hortres.2016.59
Views: 788

Received: 07 Sep 2016
Revised: 22 Oct 2016
Accepted: 24 Oct 2016
Published online: 07 Dec 2016

Abstract

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.