A basic Helix-Loop-Helix (SlARANCIO), identified from a Solanum pennellii introgression line, affects carotenoid accumulation in tomato fruits

Vincenzo D’Amelia,Domenico Carputo,Assunta Raiola,Maria Manuela Rigano,Amalia Barone,Edgardo Filippone

doi:10.1038/s41598-019-40142-3

Vincenzo D’Amelia, Domenico Carputo + Show 4 more

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https://doi.org/10.1038/s41598-019-40142-3

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Abstract

Carotenoid accumulation in tomato (Solanum lycopersicum) fruits is influenced by environmental stimuli and hormonal signals. However, information on the relative regulatory mechanisms are scanty since many molecular players of the carotenoid biosynthetic pathway are still unknown. Here, we reported a basic Helix-Loop-Helix transcription factor, named SlARANCIO (SlAR), whose silencing influences carotenoid accumulation in tomato fruits. The SlAR gene was found in the S. pennellii introgression line (IL) 12-4SL that holds the carotenoid QTL lyc12.1. We observed that the presence of the wild region in a cultivated genetic background led to a decrease in total carotenoid content of IL12-4SL fruits. To get insights into the function of SlAR, a quick reverse genetic approach was carried out. Virus-induced gene silencing of SlAR in S. lycopersicum M82 and MicroTom fruits reproduced the same phenotype observed in IL12-4SL, i.e. decreased content of lycopene and total carotenoids. Vice versa, the overexpression of SlAR in Nicotiana benthamiana leaves increased the content of total carotenoids and chlorophylls. Our results, combined with public transcriptomic data, highly suggest that SlAR acts indirectly on the carotenoid pathway and advances current knowledge on the molecular regulators controlling lyc12.1 and, potentially, precursors of carotenoid biosynthesis.

Highlights

Www.nature.com/scientificreports key players in the environment/fruit ripening interaction[1]
It is still not known whether genes coding for transcription factors (TFs) and/or other regulatory genes located in this region on chromosome 12 may influence carotenoid biosynthesis in tomato fruits
Based on genomic and gene expression data obtained, we focused on the bHLH gene mapping in this quantitative trait locus (QTL); its wild allele is present in the S. pennellii introgression subline IL12-4SL previously obtained in our laboratories[17]

Summary

Introduction

Www.nature.com/scientificreports key players in the environment/fruit ripening interaction[1]. A cross talk between different regulatory genes has been proposed to oversee, either directly or indirectly, the elaborate network controlling carotenoid biosynthesis in tomato fruits, through the regulation of the incoming flux of precursors[1,11]. Information on these regulatory genes are still insufficient. The authors found that in IL12-4 the presence of wild alleles deriving from the green-fruited S. pennellii entailed a reduction of about 36% of total carotenoid content It is still not known whether genes coding for transcription factors (TFs) and/or other regulatory genes located in this region on chromosome 12 may influence carotenoid biosynthesis in tomato fruits. To further verify the ability of SlAR to affect carotenogenesis, we carried out heterologous overexpression of the SlAR gene in Nicotiana benthamiana

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