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

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.

A comparative transcriptomics and eQTL approach identifiesSlWD40as a tomato fruit ripening regulator

“…Moreover, among the 16 genes, VIGS for two bHLH TFs (Solyc03g044460 and Solyc12g098620) showed green and light red phenotypes ( Supplemental Figure S1 ). Here, light red phenotype for Solyc12g098620 is in line with the recently published work by D’Amelia et al (2019) in which the authors reported that this bHLH TF regulates carotenoid biosynthesis. Additionally, one of the candidates, Solyc12g010950 (alcohol dehydrogenase), obtained a whitish green fruit phenotype, and another candidate, SlWD40 , obtained a yellowish fruit phenotype ( Figure 2 and Supplemental Figure S1 ).…”

Anthocyanins Are Key Regulators of Drought Stress Tolerance in Tobacco

“…Total anthocyanin amount was expressed as cyanidin 3-O-rutinoside as it was the main anthocyanin detected in tobacco in a previous study [38]. The evaluation of total carotenoids and chlorophylls was carried out according to Wellburn [39] and Zouari et al [40] with slight modifications [41]. Briefly, about 20 mg of sample was extracted with a solution of acetone/hexane (40/60, v/v) for 15 min.…”

Overexpression of PSY1 increases fruit skin and flesh carotenoid content and reveals associated transcription factors in apple (Malus × domestica)

“…In tomato, SlPRE2 , a gibberellic acid-induced bHLH TF, negatively regulates carotenogenesis by downregulating PSY and ZDS gene expression ( Zhu Z. et al, 2017 ; Zhu et al, 2019 ). Other bHLHs positively regulate carotenoid accumulation, such as papaya CpbHLH2, which activated expression of CYCB and LCYB in transient assays, and SlARANCIO, a tomato bHLH gene associated with a carotenoid QTL ( D’Amelia et al, 2019 ; Zhou et al, 2019 ). Fine mapping of the Y2 locus controlling beta-carotene accumulation in carrot found a differentially expressed bHLH TF, suggesting a potential regulatory role in carotenoid metabolism ( Ellison et al, 2017 ).…”