Virus-Induced LeSPL-CNR Silencing Inhibits Fruit Ripening in Tomato

Tongfei Lai,Ying Wang,Fengling Mei,Ting Zhou,Yiguo Hong,Pengcheng Zhang,Nongnong Shi,Yingying Zhou

doi:10.5539/jas.v7n7p184

Abstract

Fruit ripening is a developmentally and genetically programmed process. In tomato ( Solanum lycopersicum ), ripening determines fruit quality, commodity value, shelf life and many important attributes. To understand this intricate process and its underpinning mechanism, an efficient and effective approach for screening and functional analysis of ripening-associated genes (RAGs) is required. Virus-induced gene silencing (VIGS) is a powerful reverse genetics tool for uncovering gene functions in plants. VIGS has been exploited to investigate roles of RAGs in tomato ripening. However in most cases, virus-induced RAG silencing is only assessed and correlated with the chromatic change of fruits. Here we report that silencing of LeSPL-CNR through a Potato virus X -based VIGS inhibited fruit ripening and led to development of non-ripening sectors in Ailsa Craig (AC) tomatoes. Non-ripening sectors remained firmer and possessed greater relative electric conductivity and acidity as well as a higher amount of chlorophyll, but a lower quantity of anthocyanin. VIGS of LeSPL-CNR also affects expression of other key RAGs and genes associated with biogenesis of ripening hormone ethylene. These findings indicate that AC fruits undergoing VIGS of LeSPL-CNR phenocopied physical, physiological, agrochemical, biochemical and molecular characteristics of the Colourless non-ripening epimutant. Thus, the overall phenotypical changes from visual appearance to RAG expression caused by LeSPL-CNR silencing reaffirm the great usefulness of VIGS to reveal biological functions of genes crucial in tomato ripening and fruit quality.

Highlights

Fruit ripening is a developmentally and genetically programmed process which undergoes a series of physical, physiological, biochemical and agrochemical changes
We found that a lower level of transcripts was detected at the immature green (IMG) stage
In Cnr mutant fruits, expression levels of LeSPL-CNR reduced substantially and remained a very low level throughout all the developmental stages (Figure 1). These results suggest that Virus-induced gene silencing (VIGS) vector for silencing LeSPL-CNR should be delivered into Ailsa Craig (AC) fruits around the IMG stage

Summary

Introduction

Fruit ripening is a developmentally and genetically programmed process which undergoes a series of physical, physiological, biochemical and agrochemical changes. For instance fruit colours are affected by accumulation or degradation of certain pigments such as carotenoids, anthocyanins and chlorophylls. Textures and softening are associated with cell wall metabolism and cell turgor. Flavor and nutrient compositions are influenced by metabolic contents of sugars, vitamins, acids and volatiles in a diverse array of tastes and fragrances (Seymour et al, 2013). Ripening determines many important fruit characteristics including quality attributes, shelf-life and commodity values of economic and nutritional importance. It is important to understand how fruit ripening is controlled and regulated at the genetic and molecular levels

Methods

Results

Conclusion