A cucumber green mottle mosaic virus vector for virus-induced gene silencing in cucurbit plants

Mei Liu,Zhiling Liang,Ni Hong,Miguel A Aranda,Liming Liu,Baoshan Kang,Qinsheng Gu

doi:10.1186/s13007-020-0560-3

Abstract

BackgroundCucurbits produce fruits or vegetables that have great dietary importance and economic significance worldwide. The published genomes of at least 11 cucurbit species are boosting gene mining and novel breeding strategies, however genetic transformation in cucurbits is impractical as a tool for gene function validation due to low transformation efficiency. Virus-induced gene silencing (VIGS) is a potential alternative tool. So far, very few ideal VIGS vectors are available for cucurbits.ResultsHere, we describe a new VIGS vector derived from cucumber green mottle mosaic virus (CGMMV), a monopartite virus that infects cucurbits naturally. We show that the CGMMV vector is competent to induce efficient silencing of the phytoene desaturase (PDS) gene in the model plant Nicotiana benthamiana and in cucurbits, including watermelon, melon, cucumber and bottle gourd. Infection with the CGMMV vector harboring PDS sequences of 69–300 bp in length in the form of sense-oriented or hairpin cDNAs resulted in photobleaching phenotypes in N. benthamiana and cucurbits by PDS silencing. Additional results reflect that silencing of the PDS gene could persist for over two months and the silencing effect of CGMMV-based vectors could be passaged.ConclusionsThese results demonstrate that CGMMV vector could serve as a powerful and easy-to-use tool for characterizing gene function, controlling viral pathogens or even performing resistance breeding in cucurbits. Moreover, this study will possess considerable important reference value for developing different viral vectors.

Highlights

Cucurbits produce fruits or vegetables that have great dietary importance and economic significance worldwide
We developed a new cucumber green mottle mosaic virus (CGMMV)-based Virus-induced gene silencing (VIGS) vector, which produces very mild viral symptoms and efficiently triggers gene silencing in the model plant N. benthamiana and cucurbit plants such as watermelon, melon, cucumber and bottle gourd
Cucurbit plants inoculated with this vector showed viral symptoms on upper leaves similar to those of plants inoculated with the pXT1-CGMMV, and a progeny of CGMMV could be detected by DAS-ELISA and RT-PCR in these leaves (Fig. 1b, c; Additional file 1: Table S2)

Summary

Introduction

Cucurbits produce fruits or vegetables that have great dietary importance and economic significance worldwide. The published genomes of at least 11 cucurbit species are boosting gene mining and novel breeding strategies, genetic transformation in cucurbits is impractical as a tool for gene function validation due to low transformation efficiency. With the increase of consumer’s demand for high-quality fruits and vegetables and the improvement of agricultural production, it is urgent to explore genes encoding important agronomic traits in crop species, in order to breed elite, disease-resistant and featured varieties. 11 reference genomes of cucurbit species [3] including watermelon [4], melon [5] and cucumber [6] have been published, which have boosted gene mining and gene function research.

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Conclusion